esc-it.org

Welcome to esc-it.org!

esc-it is a collective that creates digital security content in the context of political activism. This site aims to serve as a knowledge base for activists and trainers, documenting current threats, countermeasures and recommendations for tools and best-practices.

Navigation

Think of esc-it like a tiny Wikipedia. You want to look something up? Simply click on the search button and type a related keyword.

The website it is structured in different categories:

• Threats: What kind of threats do activists face? What tools and techniques are used against them?
• Countermeasures: What countermeasures can be taken against those threats? This category is always kept as abstract as possible. You won’t find concrete recommendations or instructions here.
• Recommendations: What specific tools or methods do we recommend to counter specific threats?
• Instructions: Here you will find easy step-by-step instructions on how to use the recommended tools and optimize settings for security, anonymity and privacy.
• Modules: Here you will find scenarios that cover several security-related topics, to give them a bit more context to the various articles.

Get involved

Making and maintaining esc-it is a lot of work. Next to covering as many relevant topics as possible, we always try to keep all our content up to date.

Therefore, we don’t have the resources to expand the project as we would like, for example by creating video materials and improving the overall design.

We are happy if you can contribute by:

• Adding or reviewing new content. Have a look at our open issues to see where help is needed, or open a new issue if you have a topic in mind!
• Creating short explainer videos with 2d vector graphics to make the content of esc-it more accessible to people who are not able to read long or complicated texts. An example of what we have in mind can be seen in this EFF video.
• Improving the design and UX of the website, for example by creating interactive elements and animations or improving user workflows. We currently use mdBook for building the site. We are open for improvement within mdBook as well as for suggestions on alternatives!

Further information on how you can contribute can be found in CONTRIBUTING.md.

Contact

You can contact us via mail, preferably encrypted:

E-Mail: esc-it@systemli.org (PGP-Key)

Fingerprint: 0BDB 1EB8 2477 0874 9876 DAE0 B923 BEA9 EAAF 0B15

If you do not know how to encrypt your mail and prefer using Signal, you can send us your signal handle.

Social Media

Check out our social media page to get updates on the project and on current digital security issues.

Currently we are active solely on Mastodon: <@esc_it@systemli.social>

License

The content from esc-it is licensed under the CC0 1.0 Universal License, unless a different license is specified for individual texts, images, files, folders, etc.

This means that the content is in the public domain. Feel free to use and modify it. We would appreciate it if you would cite esc-it as the source and link to it: https://esc-it.org.

If your changes could be relevant to the general public, we would appreciate it if you would contribute them to this project.

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Data sniffing dogs

The following is an automated translation from this german article under the Creative Commons BY-NC-SA 4.0 license from netzpolitik.org, as it explains the topic quite well:

The irresistible smell of hard drives

“Data storage detection dogs” are increasingly being used in house searches. They can smell smartphones, hard drives, and even SIM cards. However, the police are keeping their training methods under wraps.

Everyone has heard of police dogs that search for drugs or explosives. There are also dogs that sniff out banknotes in the hunt for tax evaders. At the end of the last decade, a new type of training was added: dogs that sniff out storage media – and the German state of Saxony was a pioneer in this field. In the case of mass child abuse at a campsite in Lüdge,1 Germany’s only “data storage detection dog” at the time was deployed. As a result, the North Rhine-Westphalia police also trained such dogs and presented “Odin,” “Jupp,” and “Ali Baba” on social media. 1 A small town in Westphalia.

There are several inquiries about data storage detection dogs on the transparency platform FragdenStaat. There, one could have learned more about how the police train dogs to find CDs, hard drives, memory cards, USB sticks, smartphones, and SIM cards. Apparently, storage media have their own unique smell that dogs can recognize when they are conditioned to do so. However, the NRW (North Rhine-Westphalia) police have classified the training of the dogs as “classified information” and redacted it extensively, so instead we have to rely on media outlets such as zooroyal (a German YouTube channel) and their reporting on the “furry noses.”

A report in the Süddeutsche Zeitung (a German newspaper) states that searching for data carriers is much more difficult than searching for drugs, which simply smell stronger than standard hard drives. The Saxony-Anhalt police (the police force of the German state of Saxony-Anhalt) also write in a presentation that data carriers release hardly any odor molecules.

The Saxon service dog handler told the newspaper at the time that the dog could smell the chemicals used to manufacture the storage media. He even had the impression that his dog could find lithium-ion batteries faster than cell phones with chrome-nickel batteries and assumed that “Artus” could smell lithium.

Because the storage devices being sought give off so little odor, the “tracking work” requires “a high level of endurance and physical exertion” from the service dog, according to the documents from Saxony-Anhalt. For this reason, this training “requires focused, objective tracking behavior on the part of the service dog.”

Reward: bite sleeve

The North Rhine-Westphalia police reveal on their website how the search is conducted: “When Hank [the dog] hears the command ‘Track!’, he begins to search. If he remains motionless, Peter Baumeister [dog handler] knows that he has found something. As a reward, Hank gets his favorite toy: a bite sleeve.”

According to this, the additional training of a tracking dog to become a data storage tracking dog takes 20 days, which the dog completes together with its handler. After the training, the handler can then call themselves a “data storage tracking dog handler.” A word that could hardly sound more German.

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Forensics

Introduction

Forensics is a collective term for fields of work in which “criminal acts” are systematically investigated. In short: when cops try to find evidence.

Relevant subfields

Many forensic measures pose relevant threats to activists. These include:

• Forensic linguistics: Examines written language to identify the author of a text, for example. Relevant for anonymous letters of confession, instructions, etc..

• Physical forensics: Examines fiber traces, DNA, tire or shoe prints, and fingerprints, among other things, to identify people who were present at a specific “crime scene” or who used a specific tool, for example. Relevant for anonymous actions.

• Digital forensics: Examines data on IT systems such as cell phones, PCs, servers, printers, etc.

Digital Forensics

E.g. in the words of the German Federal Police Office:

“In addition to traditional evidence such as files (paper), images, tools, or weapons, digital evidence is playing an increasingly important role in criminal investigations. Evidence includes data carriers in countless formats: PCs, e-book readers, printers, chip cards, optical media, mobile phones/smartphones, and SIM cards.”

There are many things that can unexpectedly become (digital) evidence. Another thing that one should keep in mind is that digital forensic investigators can often restore files that were “deleted” a long time ago, which is why encrypting and securely deleting your stuff is so important.

Look at our countermeasure article about deleting data securely for more information on how to securely delete data and why it is so important.

Physical Forensics

We will not go into detail about physical forensics here. In general, classic forensic methods used in criminal investigations may also be relevant for activists. These include tracing:

• Fiber traces
• Shoe prints
• Fingerprints
• DNA
• and more

It is very difficult not to leave any physical traces. Physical forensic analysis is usually very time-consuming and costly. Nevertheless, individual case studies show that confused cops have ordered this even for minor offenses, even for simple ad busting actions.

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Loggers

Loggers are devices that can be used to ‘log’ or record something. Two types of loggers are relevant to us here: keyloggers and screen loggers.

Keyloggers

Keyloggers are devices that basically record all keystrokes on your keyboard. They are placed between the keyboard and the computer and look like normal USB adapters:

They can send every single keystroke to an attacker in real time via radio/WiFi/LTE. The problem with this is obvious.

These keyloggers are available for very little money and are easy to obtain, making them very simple to use even for amateurs. There are even keyloggers that look like normal cables, see for example the O.MG Cable.

More advanced attackers (e.g., government agencies) can also install keyloggers in the keyboards themselves by unscrewing the keyboard and installing a small keylogger circuit board directly on the keyboard’s electronics. Or they can simply replace the keyboard with a manipulated one. This would not be noticeable on the USB port alone, of course.

Screenloggers

Screen loggers work on the same principle as keyloggers. An adapter-like device is plugged between the display and the PC (depending on the connection used: VGA, HDMI, DisplayPort, etc.) and can then record the entire image transmission and send it to the attacker via radio/WiFi/LTE.

It should also be noted that “key loggers” and “screen loggers” can also refer to software loggers. However, these are nothing more than viruses and describe a completely different threat than the ones discussed here.

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Metadata

Here we describe what metadata is and where it can be found. If you just want to know how to clean metadata from files, check out our recommendations.

The data behind the data

Metadata in communication

Imagine you are writing a message to someone or talking to a friend on the phone. You might think, “As long as no one knows the content, everything is fine!” - but that’s not entirely true.

Even without knowing the content, a lot can be found out about you from the metadata.

Metadata is data about your data. In lots of messengers for example, it can reveal:

• Who is communicating with whom
• When and how often you are in contact
• Where you sent a message from
• Which app or device you are using

Metadata can be used to deduce habits and how your everyday life usually looks like.

Contact networks can also be identified in the same way: If person A is in contact with person B, and person B always immediately writes to C after receiving a message from A, then C is also connected to A.

IP addresses and location data also belong to the category of metadata. In 2024, for example, several high-ranking intelligence officials from major NATO countries were identified using a commercially available data set because they had used apps and devices that collected their location data and sold it to so-called data brokers. (Entire series of articles in german on netzpolitik.org)

It is therefore important to avoid metadata wherever possible.

According to Mike Kuketz, Briar is a role model in this regard: “The metadata generated during use is obfuscated in such a way that it is impossible to trace who was in contact with whom.”

Signal is also rather sparing with metadata. Matrix, email, and Delta Chat, on the other hand, require a lot of metadata to function properly. This metadata is then stored on all servers with which communication takes place.

This does not mean that these messengers do not have their advantages, but the disadvantage of metadata should be kept in mind.

Metadata in files

Even simple files often contain metadata. A photo taken with a smartphone, for example, may even contain the location where the photo was taken (if the settings are poorly chosen). In addition, the device model, date, time, and similar information are often included.

PDFs, Word, Excel, and similar files also usually contain a lot of metadata that reveals the device and operating system used for editing, the creation or editing date, user name of editor, and similar information.

This becomes a particular problem when files are uploaded somewhere, as the metadata is also uploaded and can then be viewed by anyone who downloads the file.

Metadata on paper

Yes, unfortunately, even printed paper contains metadata, known as printer dots. These are tiny yellow dots that some color laser printers use to leave information about the printer model and print date, which are not visible to the naked eye.

Such dots were presumably used to identify the US whistleblower Reality Winner.

Until 2017, the civil rights organization Electronic Frontier Foundation had compiled and maintained a list of such color printers. However, this has since been discontinued because all color laser printers now leave detectable traces in one form or another.

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Mobile communications

First, some basic information about threats in the field of mobile communications needs to be explained. This article focuses on how a single cell phone communicates with the mobile network in the form of a cell phone tower [colloquially: antenna mast]. The terms IMSI and IMEI (and sometimes TMSI) appear frequently and are also briefly explained here.

Who owns cell phone towers?

Cell phone towers are operated by mobile phone providers. Accordingly, the respective mobile phone providers also control the data traffic passing through these towers. In the image below, the different colors symbolize different providers (in Germany), such as Telekom, Vodafone, O2, etc.

IMSI: SIM identifier

Every SIM card has a unique identifier, the International Mobile Subscriber Identity, or IMSI for short. Due to the registration requirement for SIM cards in most European countries, the SIM card is usually uniquely assigned to an identity. The authorities can easily request this information from mobile phone providers and do so very regularly.

Authorities can ask the providers which phone numbers belong to a certain person. This can also work in the other direction, for example asking who the owner of number 0123456789 is. Those inquiries are very cheap for authorities and are regularly used on a massive scale.

IMEI: Device identifier

Mobile phone modems (i.e., the chip in your cell phone that can connect to the mobile network) also have a unique number, the International Mobile Equipment Identity, or IMEI for short. These IMEIs are usually 15 digits long and globally unique. The structure is as follows:

• The first 8 digits are, to put it simply, type-specific. For example, all Google Pixel 7a devices have the following 8 digits: 35917382

• The next 8 digits are serial numbers

• The last digit is for error correction

The IMEI therefore makes every mobile device identifiable.

If a device can be used with multiple SIM cards at the same time (regardless of whether these are two physical SIM cards or one e-SIM and one physical SIM card), it also has the corresponding number of IMEIs.

However, it is often quite easy to establish a connection between these two IMEIs:

• The serial numbers are often simply incremented (except for error correction)
• If two IMEIs are always in the same place, this can be correlated
• The manufacturers and retailers know the correlation between the two IMEIs
• If an EIR is involved, these two IMEIs are also linked to each other in the EIR. So if one of the two IMEIs is known, the second one can also be found in the EIR.

The IMEIs cannot be changed easily. In many countries, manipulating them is a criminal offense. It also requires special hardware, which is most likely to be obtained from China.

Problems when buying cell phones

So if you buy a phone in a store and pay with a card, the store will have a link between your card and the IMEI(s) of your phone. As a result, authorities may be able to trace the IMEIs assigned at the factory to specific devices by querying sellers and device manufacturers.

And if the cell phone was purchased using your own identity, this association also may exist. However, we do not yet know whether and how often authorities query this association.

Authentication

• If the mobile phone detects the signal of a cell phone tower, it tries to “knock” on it with a kind of “Hello” to see if the tower is even reachable and, if so, tells it that it would like to log into the network: “I want to log in!”

• If the radio cell receives this message, it first asks for the identity of the mobile phone to ensure that it has the right to log in: “Who are you?”

• The mobile phone then sends the IMSI of its SIM card to prove that it has the right to connect. At the same time, it also sends the IMEI of its mobile modem (i.e., of the mobile phone).

  • A Telekom cell phone tower would therefore reject a Vodafone SIM card and tell it that it does not have the right to use the Telekom network.

• This completes the authentication process and a connection can be established. The purpose of the TMSI is secondary here and has therefore been removed for simplification.

• According to the standard, such connections can only be established in “encrypted” form. In case you’re wondering why we write “encrypted in quotes, have a look at our article about IMSI-Catchers.

Both the IMSI and the IMEI are transmitted during authentication with the mobile network. This creates traceable data for mobile phone providers that enable a unique assignment between IMSI and IMEI, i.e., cell phone and SIM card.

Therefor you should be aware of this risk when using a mobile phone that has previously been used with another SIM card, which in turn allows conclusions to be drawn about your own identity. In addition, the mobile phone may also have ended up in a geofence warrant with another SIM card.

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IMSI catcher

An IMSI catcher, also known as Cell-Site Simulator or “Stingray”, is a surveillance device that “masquerade as legitimate cell-phone tower, tricking phones within a certain radius into connecting to the device rather than a tower” 1.

In general, standard telecommunication works as follows:

1. End devices, such as your phone, log in to the cell-phone tower with the strongest signal.
2. Upon receiving a request from your device, the tower performs an “Identity Request”
3. Your device then authenticates themselves with their IMSI + IMEI, and receive a TMSI from the tower.

IMSI catchers abuse the above to track the location of cell phones and gather data from nearby devices without the users’ knowledge.

A rough distinction can be made between passive and active IMSI catchers:

• Passive IMSI catchers simply wait for clients to attempt to authenticate themselves with their identifiers at the cell-phone tower. This allows detailed information to be collected about who or how many people are present at a demonstration, for example. Clients do not notice the deception due to the GSM protocol.

• Active IMSI catchers do not just wait for the client’s synchronization request. They instead give your device a TMSI (comparable to a local IP) and establish a legitimate connection to a real cell-phone tower on the device’s behalf. This allows full-fledged ‘machine-in-the-middle attacks’ to be carried out.

What security vulnerability is being exploited here?

The problem lies in the authentication between the phone and the cell-phone tower. The phone must verify itself to the tower (as shown below) with its unique identifiers (IMSI, IMEI) to prove that it has the right to use the mobile network.

However, the cell-phone tower does not authenticate itself to the phone. Therefore, the phone can never know for sure whether it is actually communicating with a normal, commercial cell-tower or with a clone, operated by the authorities.

Active IMSI catcher - system

Why is communication between the phone and the police unencrypted?

The answer can be found in the vulnerability in the communication protocol during authentication described above. By taking certain steps, the IMSI catcher can force the phone to use an old mobile phone standard (usually 2G) during the authentication process. This downgrade is possible in order to use the existing 2G infrastructure in situations where modern standards (3G/4G) do not provide reception. 2G is often somewhat more resistant in terms of territorial coverage than the more modern standards. The 2G standard, on the other hand, has long been obsolete and is not recommended for security reasons. Apart from government agencies, even private individuals can very quickly decrypt 2G “encrypted” communications and read/listen to them. For this reason, we classify this communication as “unencrypted” in practice.

Practical threats

It should be noted that this poses a potential risk if an “anonymous” cell phone is reused. In connection with radio cell inquiries, it may be possible to create and contextualize movement profiles of these devices.

A potential example scenario could look like this:

You use your action cell phone at several actions/demonstrations, preferably in different cities or states. During these demonstrations, you (and therefore your IMSI+IMEI) end up in cell-phone inquiries multiple times. At first, no one can do anything with this information except say that this device was present at all of these events. However, you might walk past IMSI catchers at further demonstrations and be checked or filmed. Over time, this could establish a correlation between you and the device.

Hardware for professional IMSI catchers in Germany and the surrounding area usually comes from Rhode&Schwarz. Their devices are known and popular worldwide, not only with law enforcement agencies. This state-of-the-art technology is also correspondingly expensive, with prices in the 4-5 digit range.

However, simple passive IMSI catchers can also be implemented with ~€25 SDR dongles (software-defined radios). These are only capable of reading existing traffic, but not of setting up a fake radio cell and carrying out actual MITM attacks.

Recommendation

We recommend reading this article from the Electronics Frontier Foundation, which introduces Rayhunter. A software, that can be flashed onto specific types of mobile routers to detect present IMSI-Catchers.

Sources

• https://www.eff.org/wp/gotta-catch-em-all-understanding-how-imsi-catchers-exploit-cell-networks
• SnoopSnitch talk: https://media.ccc.de/v/ber15-5-detecting_imsi-catchers_and_other_mobile_network_attacks, although the app itself does not work.

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Radio cell inquiry

To understand this chapter, it is necessary to understand the basic concepts of the mobile network, in particular the connection and authentication process between mobile phones and cell-phone towers. We have attempted to illustrate this in the article Mobile communications.

Radio cell inquiry is a measure that law enforcement agencies regularly use in their investigations. Thereby, the authorities request phone cell data that is of interest to the case, usually directly from the mobile operators.

How to protect against radio cell inquiries?

Don’t let your phone connect to the radio cells. Ergo, turn your phone of, or at least, put it into airplane mode. With airplane mode, bear two things in mind:

• when you take out your SIM card, but don’t put your phone into airplane mode, it may still try to connect to cell-phone towers for making emergency calls.
• not all devices truly shut off cell-phone communication when put into airplane mode.

What is requested in radio cell inquiries?

Radio cell inquiries collect the following data for the period and “location” (i.e., a specific area that may be covered by several mobile phone cells) inquired about:

• Logged-in phone numbers
• Time stamps of:
  • Dial-in/dial-out of devices
  • Outgoing and incoming calls
  • Voicemail messages
  • Sent/received text messages

Radio cell inquiries are often made before, during, and after demonstrations. This can reveal which devices were present at the protest and were they were before and after it. This information can be potentially used to identify protesters, especially when their phone numbers are registered to their names or when the route they took to the demonstration can compromise their identity.

In addition, radio cell inquiries can be used to create movement profiles over a larger area by looking at the entry and exit times of individual devices at the respective mobile phone cells:

Statistics on radio cell inquiries

For almost all countries in the world we can assume that every single phone number ends up in a radio cell inquiry, at least every few days, if not multiple time every day. Statistics on the usage are available in Germany.

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Silent SMS

SMS is the protocol by which standard text messages are delivered to your cell phone; a “silent” SMS message would deliver a “message” to the phone without you being aware of it 1. In other words, you wouldn’t see a text message or notice anything at all on your phone.

However, this creates traceable data traffic for mobile operators, as the SMS (and later also its confirmation of receipt) is forwarded to its destination via all the necessary mobile phone cells. The path taken by the SMS can then be evaluated by the authorities, allowing locations to be determined with an accuracy of up to a few meters.

There have been some apps floating around over time, that promised to detect silent SMS. The problem with those is, that:

1. The mobile modems, e.g. the chips that actually receive the SMS, are technical black boxes to the public - we can’t tell what they are really doing.
2. For most apps, your phone has to be rooted, which we strongly advice against. While it enables more user freedom, rooting breaks the fundamental security mechanisms of your mobile operating system.

Silent SMS - Application

How often law enforcement uses Silent SMS may very a lot, mostly depending on the country. As with many other threats we describe here, we don’t have a lot of concrete numbers about the usage of those techniques. What is sure is that it’s a very cheap technique, which can be easily used by most authorities without further ado.

In Germany for example, the federal authorities (which don’t include the regional ones) send between 200.000 - 400.000 silent SMS per year.

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Telecommunications surveillance

Monitoring of traffic data

This is usually what is meant when people talk about telecommunications surveillance in general. Here, the authorities force service providers to explicitly monitor your connections and to forward all recorded traffic data to the authorities. This requires a court order.

This is possible because normal telephone connections, i.e., landlines, voice calls, text messages, and (last but not least) voicemail messages, are only transport encrypted.

Transport encryption

With transport encryption, virtually every participant in the chain of transmission of a message is given the right to open and read the message.

For example, if you write a normal email, the email is first sent to the mail server with transport encryption. No one can read it in between. However, the mail server can open and scan the email. They usually do this because how else would your email providers know what belongs in the spam folder? Your mail server then sends the email, again with transport encryption, to the mail server of the email recipient. This server can also unpack and scan the email. The mail server then sends the email again, encrypted, to the recipient.

This is basically how it works with voice calls and SMS as well.

This shows that email providers/mobile phone providers, who always have the right to read your traffic, are the ideal point of attack for the authorities. There, they can knock on the door (with a court order) and demand all your data traffic. That is why it is so important to use end-to-end encryption!

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Phishing

Phishing via email or text message is generally more commonly associated with scams, but government actors also often use phishing to infect targets with malware.

There are a few things to keep in mind here. One-click malware, where users have to proactively click on a link or download something in order for their device to be infected, is much cheaper than zero-click solutions, where devices can be infected without any further action on the part of the user.

In addition, phishing attacks are relatively difficult to trace. If the phishing is discovered, it usually remains unclear who is behind the attack, which puts the attacker in a fairly secure position.

Being caught secretly bugging someone’s home is much riskier and alerts those affected. Phishing, on the other hand, ends up in all of our inboxes all the time and hardly arouses any suspicion.

Here is an example of fake links created through the clever use of Unicode characters. Can you spot the difference between the links? Which link leads to which page?

As an exception, just for learning purposes, you can now click on the two links to see what happens. Was your guess correct?

The first link does not lead to codeberg.org but to esc-it.org. The @ symbol is used as a username. This should not work if there is a / before the @, but the first link contains Unicode characters that are not “normal” slashes.

Some browsers even display a warning for the incorrect link, as shown here in Firefox:

Chromium, for example, does not display such a warning.

What is noticeable about the links is that there is a domain at the end (…@<esc-it.org>). However, this is not a clear sign of a fake and is becoming increasingly difficult to detect with ever-changing top-level domains. Here is an example with a “.zip” extension, so it could be either a .zip file or a .zip domain:

Warning: The first link leads to a domain (1312.zip) that does not belong to us. This means that we do not know what happens there. Therefore, please do not visit this link unless you know exactly what you are doing.

Here, too, the first link does not lead to a zip file on codeberg.org, but the second link does. No warning appears here either, because the domain does not yet exist.

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Public “chargers”

Public “chargers” can be found, for example, in public transportation, cafés, libraries, airports, shopping malls, etc.

Of course, a distinction must be made here between simple power outlets and USB charging ports.

The worst thing that can happen with normal power outlets is that your own charger breaks. Apart from that, your own charger is only good for charging and can’t really do anything else.

It’s a different story with USB charging sockets. For years, there have been increasing cases of manipulated charging sockets that contain not only a power source but also entire microprocessors that attempt to access the connected device. This could allow malware to be installed, memory to be accessed, and so on.

Fortunately, all (mobile) operating systems are now equipped with protective measures and ask users whether the connected “device” should be given access to the mobile phone. If you are charging you phone somewhere and a warning pops up on your device, this should make you suspicious.

This can also be prevented by only using USB cables without “data lines” for charging. These are cables that cannot be used to transfer data. You can usually test this yourself on your own computer. If you cannot access your mobile phone with the USB cable, then this USB cable most likely only has two wires: positive and negative. No data can be transferred via these wires.

So, be careful with USB charging sockets, as they may have been tampered with! Unlike tampered power outlets, where your own charger is still plugged in, a tampered power supply can seriously damage your device.

It is therefore advisable to avoid these sockets. If you have to use one, it is best to:

1. only use two-wire USB cables
2. use sockets where you have seen someone charge a mobile phone before without it being thrown off afterwards.

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Shoulder Surfing

Shoulder surfing is when someone secretly looks over your shoulder to see what you are doing or typing on your cell phone, laptop, notepad etc.

After all, even the best password is useless if it falls into the wrong hands. First and foremost, it is important to be aware of the increasing use of video surveillance. Do not enter passwords in front of cameras!

If you have ever tried shoulder surfing yourself, you will have noticed that there are places and situations that are particularly conducive to it.

In crowded lecture halls, for example, you can practically see the screens and keyboards of at least three people in front of you.

On public transportation, seats that are not directly behind the target person but diagonally behind them are particularly suitable. If the bus is extremely crowded, it is not even noticeable when someone is leaning over your cell phone while you are typing.

In such situations, it is important to not just mindlessly type your passwords, but to first evaluate the following:

• Is the potential danger of should surfing real, or is it exaggerated?
• Is it worth the risk to type in my password anyway, or can I wait/find a better place?

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Backups

Much has been written about why backups are so important, and better and worse jokes have been made about the curious fact that everyone knows this but no one seems to do it.

Backups vs. data hygiene

The biggest problem is often that we are not really aware of how much data we accumulate over the years and how important it still is to us. In our article on data hygiene, we advocate the credo of accumulating as little data as possible. But of course, this applies above all to data that is only of temporary use and would otherwise be forgotten in some corner - until it is rediscovered during a police raid.

As important as it is to store as little data as possible, we are all dependent in some way on the state and its institutions:

Official documents, health insurance, bank records, employment contracts, school records, and so on are all things that we may need from time to time to avoid sinking into complete poverty.

Perhaps even more important, however, are photos of our comrades and companions, letters from them, diaries, gifts, and other mementos. All of these are things that could cause immeasurable pain if they were suddenly gone.

Not everything listed above can be easily digitized, but most of it can.

We invite everyone to imagine that all the devices on which their passwords, photos and other personal data is stored are suddenly broken, go missing or are confiscated. Could you deal with that?

Data hygiene & backups go hand in hand

In the section above, we contrasted data hygiene with backups. Here, we would like to argue that both concepts should be considered together so that one benefits from the other.

Devices and accounts that have been used for many years, such as iCloud, Google Drive, WhatsApp, Signal etc., are often overflowing with ancient data that you don’t even know still exists.

How much data do you have on your devices that you haven’t deleted because you thought, “I might need it again someday”?

The amount of data that you have accumulated over the years is often far too extensive for you to quickly review and clean up.

However, if you had an encrypted backup of all your files, you could clean up your daily-use devices much more easily. Then, you would only carry around what you really need.

How To Backup?

We are currently working on a guide to backups for the “Instructions” category, which we will also link to below.

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Communication encryption

The encryption of all communication plays an essential role in our digital lives. In this article, we want to explain what communication encryption means, what different types of encryption exist, and what advantages and disadvantages they have.

We distinguish between transport encryption and end-to-end encryption (E2EE).

Transport encryption

Transport encryption is generally implemented with SSL/TLS. Those are encryption-based Internet security protocols that provide privacy, authentication, and integrity to Internet communications You are using SSL/TLS everyday in your browser, for example, when a padlock appears next to the URL and https appears before the URI. If this is not used, only http appears (and in most cases a warning appears that the connection is not secure).

We will use the graphic below and a practical example to explain how transport encryption works.

Example: Mail with transport encryption

Anna wants to send Arthur a message, for example by email. The example also works with other services without E2EE, such as Telegram, Discord, or chats in games. However, then there would only be one server instead of two.

Here is the example with email:

Anna has an email address on the yellow server; in our example, it would be systemli.org. Her email address is therefore anna@systemli.org

Arthur has an email address on the red server, in this case riseup.net. His email address is therefore arthur@riseup.net

Because we are talking about transport encryption, neither of them uses E2EE such as PGP. This means that Anna does not have Arthur’s PGP key, and vice versa!

The keys and locks in the graphic below symbolize so-called certificates. Each server has its own certificate with which communication to it can be encrypted. Only the server in possession of the certificate also has the corresponding key an can read the information that is sent to it.

If Anna now wants to write an email, she retrieves the certificate from Systemli (yellow lock) and uses it to encrypt her email. This is completely independent of who the email will ultimately be sent to! Arthur’s receiving address (arthur@riseup.net) is then written on the “envelope”, just like with normal mail. This email (yellow, sealed envelope with a lock) is then sent to the Systemli mail server (yellow box).

The Systemli mail server now opens the email encrypted with its own certificate and scans it for spam, for example. Above all, it looks at the recipient address on the envelope: arthur@riseup.net. The server recognizes the part after the @ symbol as the mail server to which it must forward this email: riseup.net (red server). So it quickly goes over to Riseup, grabs a copy of their certificate, encrypts Anna’s email again with it, and sends it (red, locked envelope with lock) to the Riseup mail server.

From here, this process repeats itself until the email reaches Arthur. The Riseup server unpacks the email, repacks it, and finally sends it to Arthur.

Problem

The problem here is obvious. Every participant in the communication chain can easily open and read the email. In addition, many applications (as listed above) store copies of the messages on their (email) servers. See more about network surveillance

End-to-end encryption

Once you understand the threat posed by transport encryption, the need for end-to-end encryption is almost self-explanatory.

1. Anna obtains Arthur’s lock (public key). This point is very important; please note the [TOFU] section!
2. Same as in 1.
3. Anna encrypts her message with Arthur’s public key.
4. The message remains encrypted in all steps of 4 (a-e). Only the metadata (e.g., sender/recipient address) is visible (at all possible points, including during transport!) and is read by the servers in order to forward the email.
5. Arthur receives his message. Because the message was encrypted with his padlock and he has taken good care of his key (private key), only he can decrypt the message with his key.

TOFU is bad

TOFU: Trust On First Use

The key must be verified “out of band.” An unencrypted (i.e., transport-encrypted) email makes the exchange of public keys vulnerable to interception. This is called a “machine-in-the-middle attack”.

For more information on the dangers of transport encryption, see network surveillance.

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Data hygiene

Whether it’s network surveillance, digital forensics, or house searches: surveillance is always about data that could potentially be used against you. That’s why it’s important to regularly ask yourself what data is really necessary:

• Do we need to take notes for this meeting?
• If everyone was at the meeting, notes of it may not be necessary for some things.
• Do I need to bring my mobile phone with me?
• Do I need to text my friends about the cool thing I just did?
• Bragging has been the downfall of many!

If there is no data, no one can access it. However, the assessment of a few people that certain documents are no longer necessary and that they can be destroyed may be deeply regretted a few years later. Still, depending on the stored data, simply storing documents under the bed or on an unencrypted USB drive might be too risky. So, how can data be stored securely? In any case, only in very few cases on paper!

However, most people are probably aware that simply deleting files does not mean that the data is irretrievably lost. Not even when Windows warns you that emptying the recycle bin will really make everything disappear into a black hole forever.

Deleting data securely

To illustrate what happens when files are deleted “normally,” here is a metaphor:

How Files are “deleted” - Anna & Arthur’s shared apartment

Anna & Arthur live in a shared apartment. Their names and addresses are listed in the address book (unlike a phone book, everything is sorted by address here). The apartment is the storage medium (hard drive, USB stick, SD card, etc.) and Anna & Arthur are the data on that storage medium. The good old paper phone book (these huge books, where every ones landline number and home address could be looked up at) is the so called address management system of the storage medium.

If you want to find Arthur, you enter Arthur’s address. The computer then goes to the address, fetches Arthur from his apartment, and displays him on the screen. This is normal operation when data is stored in memory and is being used.

Unfortunately, during the last action, Arthur’s mask slipped down over his nose, he was identified, and now he has to leave quickly: The data must be deleted.

If you now click on “delete,” this file will be moved to the recycle bin. Nothing is really deleted when moved to the recycle bin; just think of it as a “files to be deleted” folder.

So you empty the trash can too. What has happened now? Has Arthur disappeared?

No, you have only deleted Arthur’s name from the address book. Arthur himself is still sitting on his couch waiting for something to happen: The data is still physically on the storage medium. It is just no longer indexed in the memory’s address directory.

If the cops look in the address book, they won’t find Arthur’s name anymore. But if they simply search street by street, door by door, they will eventually come across Anna & Arthur’s shared apartment, where Arthur is still sitting.

The solution? Overwriting the data: Anna & Arthur need random new tenants.

However, this process is not standard in any common operating system (whether PC or mobile phone), as these only delete the address entries for the files. This therefore requires additional actions.

Special characteristics

• Addressing: With flash memory such as SD cards, USB sticks, or SSDs, the operating system does not know exactly which bits the data is actually stored on. There is no clear connection between physical bits and externally addressable sector addresses. Therefore, these bits cannot simply be overwritten because it is not clear which ones should be overwritten.
• Overprovisioning: In addition, these types of memory block certain address spaces from external write access, known as “reserved blocks.” This overprovisioning has three main functions: error correction, optimization of write speed, and preservation of the storage medium’s service life.

Therefore, it is not sufficient to overwrite memory cells with random bits using conventional methods. This leaves the reserve blocks untouched, from which old data can be reconstructed in case of doubt. The ATA specification provides two commands for this: SECURITY ERASE UNIT and ENHANCED SECURITY ERASE UNIT. The former overwrites with zeros, the latter with random bytes. If these commands are applied to an SSD, the reserve blocks will also be overwritten. Command line tools are available for this purpose in both Linux and Windows, but they can be a little hacky. Most SSD manufacturers such as Samsung, Kingston, Western Digital, and others provide their own tools for this purpose, which can be used.

These tools basically do nothing more than apply these commands to SSDs with their own (proprietary) firmware.

Deleting encrypted data

A more efficient method is encryption. The following applies to both rotating disks (HDDs) and SSDs:

When the data carrier is encrypted, a key is generated and stored in the header of the memory. You will be asked to set a password for the encryption. This password is then used to encrypt the key stored in the header - not the data itself.

Every data read or write operation is symmetrically decrypted or encrypted using the key.

Due to the mathematical properties of modern encryption algorithms, the bit states on the physical data carrier cannot be distinguished from random bits. An encrypted data carrier therefore looks exactly the same as one that has been randomly written to.

To securely delete this data, only the key in the header of the data carrier needs to be deleted and overwritten. This not only saves a lot of time (it takes only a few minutes), but also preserves the life of the data carrier. Completely overwriting a 1TB HDD can easily take more than 5 hours.

More detailed information can be found here.

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Password security

Good passwords are one of the most important countermeasures against data leakage. We will discuss what constitutes a good password below.

• passwords secure encrypted data, such as: hard drives and password databases
• passwords secure access to online accounts: against non-authorities!
  • authorities like the police, might be able to get a court order, because your data is stored there unencrypted, so they don’t need your password.

That’s why it’s our duty as modern activists to use a password manager. It helps us meet all these requirements without much difficulty. This way, we not only protect our own access, but also the information behind it that is linked to our comrades!

In this article you will find explanations on:

• What a password manager is capable of
• What a good password is
  • What second factor authentication means and why it is recommended

Password managers

A password manager stores all your passwords in a single encrypted database (which is just a file) protected by a master password. This means that your passwords are not stored in plain text on your system or on paper in your home, and you don’t have to remember them all yourself.

Since you no longer have to remember passwords yourself, it is not a problem and is also recommended that you generate a separate, strong password for each account. This is very easy to do with the password manager itself.

The password manager also stores the assignment to websites & apps for which you have generated the respective password. This also makes phishing more difficult, because the password will not be displayed as a suggestion on a false URL.

As mentioned above, the password manager itself is protected by a strong master password and/or other factors (see below 2-factor authentication). This is therefore (apart from hard drive encryption) the only password you really need to remember and can therefore be a little more complex. The rule is: it is better to remember one strong password than many insecure passwords.

Strong passwords

Okay, but you still need at least one strong password for the password manager. But when is a password strong?

An important basic requirement is that the password is generated randomly. Anything you come up with, no matter how clever your system may be, should be considered insecure.

Optimized algorithms enable authorities to search specifically for possible passwords used by activists by trying out vocabulary, quotes from revolutionary writings and songs, etc., while saving time and energy by avoiding fascist vocabulary, for example.

“History is a history of class struggles” may have seven words, but for the reasons mentioned above, it is a very poor password!

Here you can already see that the term passwords also refers to passphrases. Passphrases are randomly generated strings of words. They have the advantage that people can remember much longer strings of characters.

We explain below where the numbers 5 and 7 come from. There, we look at how long it would theoretically take to crack a randomly generated password or passphrase. However, these tables are always subject to many ifs and buts.

2-factor authentication

2FA ensures that simply entering a password is not sufficient for complete authorization, as it is assumed that passwords may be corrupted. Therefore, a second instance is requested for complete authorization.

The recommendations for password managers include an example scenario showing how a KeePassXC database can be secured with a second factor.

The second factor can be based on various characteristics:

2nd factor: Possession

You need a special device that either displays a number or must be plugged into the computer via USB. If the attacker does not have this “device,” authorization will not be granted. (Hardware tokens, 2FA apps, SMS)

TOTP software

TOTP stands for time-based one-time password and can be set up with all common password managers such as KeePassXC. The login process then consists of entering your username and password, after which you will be asked for the TOTP (e.g., a 6-digit PIN), which changes every ~30 seconds.

USB hardware tokens

These look like normal USB sticks. If a service/hard drive or similar configured with this token is to be unlocked, the stick must also be inserted into the device being used. These tokens are often protected with a PIN, so stealing them is not enough. The number of PIN attempts is limited.

Since all of this is implemented and protected at the hardware level, it is a very secure method of authentication. (The relevant standard for security tokens of this type is called FIDO2, the old standard is U2F.)

TOTP hardware tokens

Similar to TOTP software, but not in an app such as a password manager, but as a thumb-sized device. They have a small screen that displays the 4-6 digit TOTP, which changes every ~30 seconds.

When logging in, the code displayed at that moment must always be entered as 2FA. However, the standards for tokens of this type are usually not open source, which is why we do not recommend using them.

SMS

Probably the better-known method. To verify the identity of the user, the respective service sends an SMS to the phone number registered with the account. Since the mobile network cannot be considered secure, we do not recommend this method.

2-factor biometrics

Unique biometric characteristics must be verified during registration (fingerprint, facial recognition, iris scan). Biometric authentication is particularly widespread for smartphones.

However, biometric authentication poses a problem for us in that the authorities can simply use our biometric characteristics under duress and by force. We therefore advise against biometric unlocking methods such as fingerprint and Face ID as a matter of principle.

The only exception to this is GrapheneOS, which offers a PIN as a second factor limited to twenty attempts for fingerprint recognition and otherwise meets the highest security standards.

2nd factor: Knowledge

For example, the security questions that were common in the past, such as “What is your place of birth?” However, these “security questions” usually imply answers that someone who knows you well could easily find out for themselves. We therefore don’t recommend them.

Time to crack

In reality, how long it takes to crack a password depends very much on the exact circumstances. The calculations here assume a very specific scenario. The scenario shown here assumes very favorable conditions for the attackers. This means that in practice, it will take even longer.

Time to crack a password

It should also be noted that these times are for one password from one person. All of the hardware is busy with this task, so no other passwords can be cracked during this time.

Important prerequisite: The password must have been generated randomly! This means that this is purely character brute forcing. So, for example, you start with 0000 and try:

• 0001,
• 0002,
• ...,
• AAAA,
• AAAB,
• ...,
• A-A-A-B-B,
• R€70lut10n,
• …

etc. without word lists optimized for the target person.

Time to crack a passphrase

However, a random password that is sufficiently long and contains letters, numbers, and special characters is difficult for humans to remember. That’s why we recommend using passphrases for passwords that you need to remember, such as those for your password manager and the hard drive of your computer and phone. These consist of words instead of individual letters. They are much easier for humans to remember, but are no less secure than passwords. See also: xkcd 936

For example, the word case is assumed below, namely that the attackers know exactly how many words from which language and in which format (i.e., upper/lower case, which characters between words) were used for the password and that they use (in the left column) the hardware used to train ChatGPT to crack it. Therefore, these graphics should not be taken at face value.

As already mentioned, random passphrases can be created using password managers or, in a similar way, with dice and a word list that is as large as possible.

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WiFi SD cards

Photographers in particular often face the problem that their newly captured images are stored unencrypted on their camera’s SD cards until they can transfer them to encrypted hard drives once they are back at their laptops. Added to this is the problem that storage media such as SD cards, USB sticks, and SSDs are very unreliable or even impossible to delete securely if the data on them was unencrypted.

So-called Wi-Fi SD cards can help in solving this issue. Like normal SD cards, they are simply inserted into the camera’s SD card slot. However, they do not actually store any images. Instead, they are connected to a mobile phone via Wi-Fi (direct) using an app and send every image taken immediately to the mobile phone. Since your phone is (ideally) encrypted, the data is then better protected.

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Clean up metadata

The following is mostly taken from the entry on metadata in the Systemli Wiki.

Exifcleaner

Platform: Linux, Mac, Windows Exifcleaner is an application for removing metadata from files.

Metadata Cleaner

Platform: Linux Metadata Cleaner is a popular program for deleting all metadata from various file formats with a single click. It supports all common file formats and is very easy to use. It is based on Mat2, which is presented here. Mat2 is particularly interesting to us because of its web application, which can be a good alternative for on the go.

Mat2

Platform: Web browser (online, all systems) and file manager (offline, Linux)

Mat2 is pre-installed on the anonymous operating system Tails and can be installed on other Linux systems. Instead of being a standalone program, mat2 is installed as an extension for the file browser and used by right-clicking on the file to be cleaned up.

Web application

You can also use mat2 without installation as a web application at https://metadata.systemli.org. The files are uploaded to the Systemli server, cleaned up there, and then you can download them again. The web application is therefore an alternative for when you are on the go.

Scrambled Exif

Platform: Android

Scrambled Exif is an open-source app for cleaning up image files. You can download the app from the Google Play Store or F-Droid. After installation, you need to open the app once and give it permission to access your storage in order to set it up. Then, every time you want to share an image, you can share it via Scrambled Exif. It will clean up the file and ask you which app you want to share the cleaned file with.

Printerdots

As described at HacksAndLeaks: Instead of uploading original documents whose printer dots could reveal your identity, it is better to type or reproduce the originals by hand, print them on an “anonymous” printer, and publish them that way.

Anonymize scanned documents

Okular

Platform: Linux, Windows, (MacOS officially only with unstable version, but works quite well according to experience)

Okular is a PDF viewer that can also be used to black out documents.

Obfuscate

Platform: Linux

With Obfuscate, image files can be reliably pixelated/blacked out.

Libre Office

Documents can also be blacked out with Libre Office. However, most people find the above methods much more intuitive and simpler. An older but very good English-language guide can be found here.

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GrapheneOS

GrapheneOS is a mobile operating system based on Android. It is often recommended as an alternative to pre-installed (OEM) operating systems, as it can be used entirely without Google services. In addition to this feature, which protects user privacy, GrapheneOS, in combination with supported devices, offers state-of-the-art security features, which is why we strongly recommend its use here.

Recommended Apps

GrapheneOS comes as a very blank operating systems, with just the very necessary tools installed. Because app installations are crucial to security, we would like to give a recommendation on how to install apps from which sources/app stores.

We consider the following apps as part of most activists standard installations. The following list, as far as necessary, contains links to our instructions on how to install those apps securely, on a fresh GrapheneOS installation. We:

• Accrescend App Store: `Accrescend is a trusted app store that can be installed by the default GrapheneOS app store
• Signal messenger
• F-Droid: F-Droid provides apps, that Accrescend does not
• Orbot: Orbot routs all your phones network traffic through the Tor network
• Tor Browser
• CoMaps: is an offline map. Simply install it from F-Droid

Recommended settings

Confidential profile

For many, data-hungry apps such as WhatsApp and the like are still a must-have in their digital repertoire. As a result, separate work profiles are often set up to use these apps. The “private space” feature can be a welcome alternative here:

The GrapheneOS team has written this feature announcement, which gives further details on how the private space feature can be used.

It is important to note that the confidential profile has its own network settings. This means that if you use TOR or VPNs, you have to set this up again in the confidential profile, as the settings from the normal owner profile do not apply here. This can also be seen a privacy feature, since exit IPs can be separate.

Data protection & security

Exploit protection

In the settings under Security and Privacy > Exploit protection:

auto reboot

This option defines when your phone auto-reboot, measured by the time since last unlock. The auto reboot time should be as low as possible, but still comfortable for users. After rebooting, no signal messages/calls will be received without first unlocking the device, for example. However, a lower reboot time can possibly protect your data from physical extraction in cases where it was confiscated. It puts a limit on how long attackers have to try to exploit the device while the user is still logged in, since it’s going to reboot automatically if it’s not successfully unlocked in the defined timeframe1.

USB - C Port

This option controls the behavior of the USB-C Port. It should optimally be set to “Charging only”. The “Charging only when locked” option is one level less strict and thus potentially less secure, but it is necessary if you want to transfer data over the USB port, e.g. when using a USB drive or connecting the phone to a PC. In general, the order of the options is, from top to bottom, the most secure to less secure.:

• Off (Disables the USB port completely. Can still charge, when device is off)
• Charging-only (USB can be used only for charging)
• Charging-only when locked (When the device is unlocked, data can be transferred, otherwise only charging is enabled)
• Charging-only when locked, except before first unlock (see)
• On (Data transfer is alway enabled. Not recommended!)

Turn off WiFi & Bluetooth automatically

Turning of WiFi and Bluetooth when not needed is good not only for your battery life, but also for security and privacy. A convenient time period should be selected for both.

More Security and Privacy

In the settings under Security and Privacy > More security and privacy:

• Notifications on lock screen: This should be turned off. In case you phone gets stolen, the thief can see all incoming messages, including the names of the persons who sent them. This is a major security and privacy risk.
• Allow Sensors permissions by default: This should be turned off. This way, you will be asked about the sensor permissions you want to give an app, every time you install one. By this, you will have more consciousness about what different apps are capable of.

Duress Password

• Duress password: A duress password ensures that when it is entered, the phone is completely reset to factory settings. This is very useful if you are ever coerced or forced to unlock your phone. This also works if an attacker tries to guess your password using brute force. Of course, having regular backups of your phone or at least of your critical data is needed to ensure the reset does not lead to data loss.

It is best to choose a Duress Password that:

• you can remember immediately also in stressful situations. this is important so you can quickly type the duress password when needed
• that the police or your adversary would likely guess, so your data would be wiped if an unlock is attempted
• one that you would never choose as your real password, so that people who know you would not accidentally wipe your data if they try to unlock your phone

WiFi

For all WiFis that you do not have full control over:

• In the settings for the respective connection (gear icon next to the WiFi name): activate non-persistent MAC address randomization for this connection. This is a privacy feature which makes it harder to track or identify you via WiFi.

2FA for fingerprint

It has recently become possible to use a second factor for unlocking your phone via fingerprint. This represents a huge step forward in the conflict between usability and security!

What was the problem before?

Normally, biometric unlocking methods should be used with extreme caution for the simple reason that they can be forced by others. In case of doubt, the police can force your finger onto your phone and unlock it This means that, until now, the use of biometric unlocking has always been accompanied by the risk of being taken by surprise and forced to unlock your phone before it can be turned off.

What is the solution?

The 2FA option offers the possibility of setting up a minimum 4-digit (6 digits are recommended) PIN number, which must be entered each time after the fingerprint to unlock the phone.

You still have to type something, but a 6-digit PIN on the large number pad is much easier and faster to type than a 7-word passphrase on the small keyboard. In addition, the PIN can be changed much more easily when necessary, as you don’t have to worry about learning a new long password.

Your password should still follow the recommended passphrase guidelines, but using this feature means that the cell phone can be encrypted with a very strong password without having to type it several times a day, since the long password is only required when the phone is first unlocked.

Can the PIN be brute-forced?

Only to a very limited extent:

• The entire fingerprint method is only available for 48 hours after the last entry of the primary (long) password.
• A maximum of 4 * 5 failed attempts are allowed. There is a 30-second timeout between every 5th failed attempt. This means that there are a maximum of 20 failed attempts. [1].
• As long as your PIN is truly random and thus hard to guess (not your birthday, for example), it can be considered secure.

PIN scrambling

PIN scrambling is pretty nerdy, but it does have its use cases:

Depending on whether you already have enabled the 2. factor pin for fingerprints, the locations are different from each other. See here in our instructions.

Instead of the digits always being displayed in numerical order on the screen, the digits are displayed in random positions on the screen when the PIN is entered. This means that if an attacker has been watching you entering your PIN from a short distance and has only been able to see the direction of your thumb on the screen, for example, they will not be able to reconstruct your PIN. The same applies to CCTV / surveillance cameras.

PIN scrambling is also available for the fingerprint 2FA.

Apps

In the settings under Apps > Special app access:

• Install unknown apps: Here are all apps listed that could potentially be able to install other programs on your phone. Check this list, so that only the app stores you use, are allowed to install other apps, such as: Accrescend, App Store, F-Droid, Aurora Store and so on …

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Messenger

While emails are still regularly used for digital communication, messengers have become more popular in recent years.

One advantage of (good) messengers over emails is that encryption and secure communication are part of their initial design, while email is unencrypted and rather insecure by default.

Some criteria for what constitutes a good messenger can be found at PrivacyGuides. For activists, depending on the threat model, it is particularly important to have secure and anonymous communication.

Two messengers that are widely used in activist circles and can be recommended are Signal, Matrix and Delta Chat.

Signal

Signal was developed by the anarchist Moxie Marlinspike and is one of the best-known alternatives to the monopolist messenger WhatsApp.

Advantages of Signal

• Easy to use: Signal is simple to install and everything “just works.” There isn’t much you can do wrong that would compromise security.
• Widespread use: As of January 2025, the platform had approximately 70 million monthly active users. While this is still far behind WhatsApp’s 2 billion users, it is nevertheless widespread, in contrast to some other Messengers in this list.
• Secure encryption: Signal has its own communication protocol that is open source and regularly audited. Some other messengers, such as WhatsApp, have also adopted the protocol, meaning that it is used daily by billions of users. Communication in Signal is therefore securely end-to-end encrypted.
• Data minimization: Signal stores as little as possible about its users and can therefore only disclose very little information when forced by authorities to hand over user data. The only data that Signal was able to disclose in past court cases was the date the account was created and the date the account was last used. When legally forced to provide information to government or law enforcement agencies, Signal discloses the transcripts of that communication here.
• Option for automatic deletion: Chats can be set to automatically delete messages after a certain period of time. This means that they are secure even if the police gains access to the device (but only after this period).

Disadvantages of Signal

• Anonymity: Signal was not designed to be anonymous, but to provide secure encryption. As of today (December 2025), a phone number is required to register. In many countries, phone numbers must (legally) be registered to a real person. The phone number used to be visible to everyone you communicate with, but Signal now enables users to hide their phone number from other users. When using a phone number that is not linked to your identity for registration, Signal can therefore be considered as anonymous as the other messengers in this list.
• Based in the US: The Signal Foundation is based in the US and can therefore be forced to to hand over data to intelligence agencies. However, Signal has very little data that can be handed over.
• Centrality: Signal only runs on its own infrastructure (which is located at Amazon, Microsoft, Google, and Cloudflare) and cannot be self-hosted. This means that users must trust Signal to some extent to do its job well. On the other hand, a compromised signal server does not mean that all your chats are also compromised, as long as your security numbers stay verified. But, it does mean that there is a central point of failure: If signal gets shut down one day, you may need another channel of communication to your contacts.
• Censorship: Since Signal is centralized, it is possible for governments to try to block connections to Signal servers. While Signal introduced Proxys that can bypass censorship, it makes the bar-of-entry higher. Statistics from other projects such as the Tor project show that usage of a technology significantly declines when it is censored, even if there are ways to circumvent it. The plans of the EU to possibly introduce “Chat Control” and Signal’s response that they may will exit the European market if the proposed regulation is passed highlight this issue. If the law passes, EU users may need to rely on Proxys to connect to Signal or fallback on alternative messengers

Signal groups

Signal groups are popular and frequently used for communication in larger groups (up to ~150 contacts). In general, Signal chats offer automatic deletion of messages after a set period of time, which should also be set for groups that have a higher risk potential.

Unfortunately, there is no function yet that automatically deletes entire groups after a set period of time. Therefore, especially when devices are confiscated, it is important to consider which contacts are connected in which groups (or which group names!) and could also be compromised.

We therefore recommend (for all group chats, not just on Signal): Based on the principle of plausible deniability, give your groups names that are as inconspicuous as possible and that cannot be used against you! In case of doubt, the chat history will only show that the group name has been changed, but not what the group was called before.

Matrix

Matrix is a communication protocol. There are various client apps for this protocol, the best known being Element.

Matrix has become increasingly popular in activist and hacker circles, especially in recent times.

How it works

The most important difference between Matrix and other messengers, such as Signal, is its decentralization, or federation. Similar to email, there are many different servers (“home servers”) (such as matrix.org or matrix.systemli.org). If an activist with a Matrix account at matrix.org communicates with an activist with a Matrix account at matrix.systemli.org, the (encrypted) messages must be synchronized between the two servers.

Advantages of Matrix

• Secure encryption: Matrix uses its own implementation of the Signal protocol. It has some disadvantages compared to the Signal protocol, but is still similarly secure.
• Decentralization: Matrix is federated and therefore decentralized. There are many different servers that communicate with each other, so there are many points that would have to be attacked to completely paralyze Matrix. It is therefore more resistent to censorship then Signal, both legally and technically.
• Anonymity: Some servers do not require any personal information to create an account. This makes it possible, in principle, to use Matrix anonymously.
• Openness: The source code of Matrix and Element is open source and can be audited for security.

Disadvantages of Matrix

• Complicated to use: Matrix can be complicated to use at times. The principle of federation is counterintuitive for non-technical people, there are many different clients to choose from (which be overwhelming), and some things do not work smoothly yet.
• Not yet widely used: People often need to be persuaded to set up a Matrix account.
• Lack of data minimization: Because Matrix is federated, all data must be synchronized across all federated servers. This also means that it is practically impossible to delete data. By default, the Matrix ID, personal information, usage data, IP addresses, device information, other servers with which communication takes place, and room IDs 1 are stored on all servers by default.

[1]: The source refers to an older version of Matrix. It is unclear to what extent the amount of data stored by default and the deletion behavior are transferable to current versions.

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Password manager

KeePassXC and Bitwarden are both open source and have applications for all common operating systems/browsers.

KeePassXC works offline, Bitwarden online. However, KeePassXC can also be synchronized across multiple devices using external services.

Practical password managers for PCs:

• KeePassXC: Linux, Windows, MacOS
• Bitwarden: Linux, Windows, MacOS
  • Keep in mind, that for using Bitwarden, you will need a provider that runs a Bitwarden service and that you trust. Don’t use untrusted providers.

The password managers integrated into browsers and operating systems are not necessarily recommended, as they are often proprietary and designed primarily for convenience. This regularly leads to security vulnerabilities. Browsers in particular are always a target for attackers and offer many attack vectors.

KeePass for mobile devices

Recommendation from the official KeePassXC documentation:

• Android: keepassDX, Keepass2Android
• iOS: Strongbox, KeePassium

KeePassXC

KeePassXC is one of the best-known and most widely used password managers. It is open source, regularly checked for vulnerabilities by experts, and offers a variety of very practical features. These enable us to bridge the gap between security and convenience.

Browser integration

There are plugins for KeePassXC for all common browsers (except Safari) to conveniently use the auto-fill function. This automatically suggests the correct login details on every website for which passwords have been saved.

This prevents you from accidentally entering your password when you click on a phishing link, because the plugin recognizes that you have landed on the wrong URL.

Key file

It is recommended to secure a password database with both: a password and a second factor. The easiest way to do this is with a key file. (See below for an example scenario.)

Key file as second factor

It is possible to encrypt the database with a separate key file in addition to the password. This means that you always need both the password and the key file to access the passwords.

Instructions for doing this can be found here.

Key file as master key

You can also encrypt your password database with just a key file, without a password. Then you must always select the key file when opening the database in KeePassXC.

Key file as master key with 2nd factor password

A common use case for this is to store the key file on an encrypted USB stick, which you always carry with you, e.g. on your key ring. This also ensures 2-factor authentication. The following is required:

1. factor: the password for the stick
2. factor: the stick (with the key file)

to access the passwords. It is essential to ensure that there is a backup USB stick in case the actual stick is lost!

Generate new passwords

One of the core features of a password manager is that it can generate strong passwords or passphrases according to your own specifications. This ensures that you don’t reuse the same password out of convenience.

Synchronize and back up passwords in the cloud

Isn’t that dangerous?

The password database is always encrypted, at all times. It is never decrypted in the cloud, so the cloud operators cannot read it. However, the police could potentially steal a copy of your database, as described in the following example scenario.

Example scenario

Let’s assume that your password database is “only” protected with a (strong) password. If the police have access to your cloud (or obtain your database in some other way), they will only have the encrypted file and will not be able to do anything with it.

However, if they find out your password in the future (e.g., by secretly watching you type it in), they can retrieve the encrypted database and decrypt it.

If the database were also encrypted with a key file, it would not be enough to know the password; the key file would also be needed. If you were to destroy this key file, there would be no way to decrypt the stolen database.

How To

For example, you could store your database in the cloud and access it from all your devices.

The key file is stored only locally on your devices.

If you suspect that the authorities have obtained a copy of your password database

1. make a copy of your database
2. create a new password
3. and a new key file
4. and then delete the old key file from all your devices.

This will render the compromised database useless forever.

In both cases, all your passwords would be irretrievably lost.

KeePassXC as a 2-factor app

KeePassXC can also be used as a 2FA app with TOTP. This even works on the apps for mobile phones.

Instructions

Here you will find instructions with further references.

Note

We consistently refer to KeePassXC here.

Older versions such as KeePassX and KeePass should no longer be used.

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Auto Reboot

Because all encrypted devices store their encryption keys in their RAM after you first entered the device password during the start up, bad actors could try to read your encryption keys out of the RAM, even when your device is just screen locked.

Because of this, we want to automatically turn off our devices to clear our encryption keys from the RAM.

Automatic reboot can be configured on all PC platforms and some Android devices. Instructions for the native functions of the various platforms are provided below. No additional programs need to be installed.

PC

Linux

On Linux, you can use crontab for automatic jobs such as auto reboot. For example, to set the PC to restart every morning at 4 a.m.:

• Open Terminal (Command Line)
• Enter this command in the terminal: sudo crontab -e

An editor will now open (or you will need to select one, TIP: select nano)

• Paste the following line at the bottom: 0 4 * * * /sbin/shutdown -r
  • To do this, copy the line above
  • Go back to the command line in the editor
  • Right-click > Paste
  • First press Control + S for “safe”
    • then press Control+X for “exit”
  • Done

MacOS

• Click on the Apple logo in the menu bar.
• System Preferences
• Energy Saver
• Schedule

The top checkbox can be used to specify when the PC should be restarted when it is turned off. We are not interested in this. We want to automatically turn off the PC to clear the RAM.

• So we select the bottom checkbox
• Every day
• Choosing the reboot time is up to you, but we would recommend a time at night (e.g., 2 a.m.), as this is when we usually do not use the computer. Additionally, house searches are often conducted in the morning, so rebooting our computer beforehand makes sense.

Windows

We can use the Task Scheduler to shut down the computer, restart it, or perform any action once or at regular intervals.

If you prefer to follow a video tutorial, there is also YouTube video on this topic.

• Enter taskschd.msc in the Start search and open Task Scheduler.
• In the right-hand bar, click on Create basic task
  • Give the task a name, e.g. Auto Reboot
  • Execute whether the user is logged on or not
• Go to the next tab and select Triggers
  • Daily
  • Set the restart time (e.g. 2 a.m.).
  • Start date and start time: Select the current time i.e. valid from now
• OK and go to the next tab Action. Here, select Start a program
  • Now enter shutdown in the Program/script field
  • Now enter /r /f in the Add arguments field
  • The \r stands for reboot. If you only enter /f there, the PC will not restart automatically, but will simply remain off.
• Next and go to the next tab Conditions
• Make sure that under the “Power” section:
  • the top two checkboxes are unchecked, i.e. off
  • and the last one, “Wake the computer to run this program,” is checked.
• Click Next to check everything and then click “Finish.”
• Finally, you will probably have to enter your password.

Mobile devices

Android

An automatic restart can also be set on common Android devices. GrapheneOS even offers the option to restart the device whenever it has been unlocked for X hours.

A restart at a fixed time can be set as follows:

• Settings
• Utilities
• Scheduled power on and off

Here you can now specify when the device should always shut down and when it should restart.

iOS

Unfortunately, iOS does not currently offer a function for scheduled restarts.

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Backups

In the article on backups in the countermeasures section, we described why backups are so important. Here we want to show how backups can be made.

Backup of what?

Of course, everyone has to think for themselves about what needs to be backed up. Here are a few common examples:

• Passwords
• Contact details (phone numbers, email addresses, etc.)
• Official documents
• Texts you have written yourself (or others have written)
• Logs (if necessary)
• Chats (if necessary)
• Images (photos, etc.)

How to back up

There are, of course, many ways to make backups. From simple copying and operating system functions to powerful programs such as borg/rsync, Kopia, or others.

Copy manually

The simplest way to back up is, of course, to simply insert a USB stick into the computer and copy your important files (user folder) to it, or to copy all folders from the file manager on your mobile phone to it. However, this can be very inefficient, as new data that needs to be backed up is constantly being created. Then you have to evaluate each time which files and folders need to be copied again.

Native backup functions

MacOS

MacOS makes it very easy for users to make regular backups. The in-house tool is called Time Machine. Apple’s own instructions are very easy to understand.

All you need is a storage medium that is large enough. In this case, large enough means at least twice the size of the data to be backed up.

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GrapheneOS

Recommended Apps

Install Accrescend

Download the Accrescend App Store from the default App Store, that comes preinstalled with GrapheneOS From Accrescend install App Verifier and Inter Profile Sharing, if you plan to share files between different Android Profiles

Install Signal

• Download the Signal APK from Signals own website: https://signal.org/android/apk/. After downloading the APK, verify it via the App VerifierYou can do so by selecting the downloaded APK in your Downloads folder and share the APK with the App Verifier. This will display SUCCESS at the top. On the bottom it can say UNKNOWN, that’s ok. If the top also says UNKNOWN, than something went wrong and downloaded a wrong APK!
• Go back to the Download folder and click on the signal APK to start the installation.
• In case the warning For your security, your phone currently isn't allowed to install unknown apps from this sources. pops up, this is correct. You have to give you Files App the permission to install Applications. Click Settings and toggle Allow from this source

Only for very high threat levels:

If you are at home, in your personal WiFi and you want to active you signal anonymously, wait with the activation of your account until you installed Orbot from F-Droid. Just follow the guide below.

Install F-Droid

• As with signal, get the APK from their official website: https://f-droid.org

Your Browser Vanadium might show you a warning, that This file might be harmful. This is also a good warning, since usually one shouldn’t download random APK’s from the web, but instead from an app store, like F-Droid. Since we don’t have an app store yet, from which we can install the apps we like, we need to do this once: Download anyway

• Share the downloaded APK with the App Verifier and confirm the “SUCCESS” at the top of App Verifier

• Go back to the Download folder and click on the signal APK to start the installation.

• In case the warning For your security, your phone currently isn't allowed to install unknown apps from this sources. pops up, this is correct. You have to give you Files App the permission to install Applications. Click Settings and toggle Allow from this source

Install Orbot and Tor Browser from F-Droid

Orbot will direct all your phones internet traffic through Tor.

First, you have to copy the guardian projects repository link from their website. The link on the very top of the webpage should work.

• add the repository of the guardian project to your F-Droid by following these instructions

• go back to the main page of your F-Droid App and pull down on the screen, to refresh the page. Now the newly added repositories should be included

• search for Orbot from the “Guardian Project” and install it

• search for Tor Browser from the “Guardian Project” and install it

Recommended Settings

Device Unlock

In the settings app, go to: Security and Privacy > Device unlock. Here you find settings for:

• Screen lock: set your strong password here
• Fingerprint unlock and it’s strong 2FA feature
  • also see the PIN scrambling feature
• Duress Password
• PIN scrambling:
  • if you don’t use the fingerprint unlocking with it’s 2FA Pin: Device unlock > Cog-Wheel icon to the right of Screen lock > Scramble PIN input layout
  • if you’re already using the 2FA method, than you have to go to: Device unlock > fingerprint unlock > input your password > second factor PIN > toggle Scramble PIN input layout

If you’re interested why this is in two different locations, see: https://discuss.grapheneos.org/d/18661-where-is-pin-scramble-feature/11

Exploit Protection

In the settings app, go to: Security and Privacy > Exploit protection. Here you find settings for:

• auto reboot
• USB-C Port Tipp: Charging only
• Turn off WiFi & Bluetooth automatically

More Security & Privacy

In the settings app, go to: Security and Privacy > More security & privacy. Here you find settings for:

• Allow Sensors permission to apps by default. Tip: turn this off

Apps

In the settings under Apps > Special app access:

• Install unknown apps

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KeePassXC

Below, we summarize what we consider to be the most important points from the KeePassXC documentation linked above. Throughout the article, we refer back to the individual sections of the KeePassXC documentation. If you find it difficult to follow so much text, this video, (on YouTube), explains the core features of KeePassXC quite well. Once you are familiar with the basic usage of KeePassXC, there is also a sequel for advanced use cases.

Create a database

The database is basically just a file in which passwords are stored in encrypted form. It always ends with .kdbx

KeePassXC is the program used to decrypt and use this file.

If you don’t have a database yet, you must first create a new one. Before you create your first database, you need to consider the protection methods you want to use. The simplest form of protection is to use a strong password. For additional protection, you can consider adding another protection “layers”, such as a key file (key files).

To create a new database without a key file, follow the steps in this guide: Create new database

Key file

When creating the database, there is a button labeled “Add additional protection” where you set the password for the database.

Then, under the “Key file” field, click the Add key file button.

Here you can now either:

• Create a new key file.
  • Generate: Specify a name and location for saving the new key file
• Specify an existing key file to be used to encrypt this database:
  • Browse: Here you can select your existing key file

Decrypt database with key file and password

If you have protected your database with a password and an additional key file, you will need both to unlock it again:

• Open the database with KeePassXC
• I have a key file
• Select the key file in the file manager
• Enter the password
• Confirm

Add key file later

If you already have a password database, you can also add a key file later.

We strongly recommend that you back up your database beforehand. This will prevent the loss of all passwords if something goes wrong. To do this, simply make a copy of the database with a new name. For example, if the database is called “Passwords.kbdx,” create a copy called “Passwords-keyfile.kbdx” or something similar.

• Open the (new) database in KeePassXC
  • Now you may have both databases open at the same time:
  • This is not a problem, but be careful not to get confused and edit the wrong database. Close the original database, so that nothing goes wrong.
• In the top bar, click on Database
• Then click on Database security...
• From here, follow the instructions in the section on adding a key file
• Caution: Once you have created and saved a key file, KeePassXC assumes that you now want to use **only this key file to unlock the database. If you have already clicked OK, you will have seen a warning message to this effect.
  • Therefore, you must reset and confirm the password using Change password.
  • OK

Password entries

Follow the official documentation to create a password entry.

You can also edit existing entries later (double-click on the entry).

Browser integration

KeePassXC can be integrated into you browser. The integration makes it possible to automatically fill Browser Log-Ins for passwords that are saved in your Database. This saves a lot of time, as you don’t need to manually copy-and-paste your passwords into the browser.

There are official instructions for installing the browser plugin (except for Safari).

TOTP

Official KeePassXC instructions with helpful screenshots.

TOTP is a form of two-factor authentication used by many web services, such as email or cloud access. To set up 2FA for a service, you need two things:

1. The appropriate setting in the web service, e.g. in the email settings.
2. The configuration of the corresponding KeePassXC entry for this web service.

The settings for web services all look slightly different, of course, but in most cases you will find the following in the account settings:

• A section with Security or Privacy.
• Here you should find the 2FA or TOTP settings.
• “Enable TOTP” or similar

Now a QR code and, in the best case, a random string should appear (see KeePassXC instructions). The QR code is useful if you set up TOTP on your mobile phone, as you can easily read the Secret with the mobile phone apps using the camera. On a PC, we need the character string for this.

If only the QR code appears here without the character string, we have to read the “Secret” from the QR code.

• Copy secret

Now we go to the KeePassXC database:

• Right-click on the corresponding password entry
• TOTP
• Set up TOTP
• Paste Secret
• OK

Now you should see a small clock next to the password entry. This symbolizes the temporary nature of the TOTP codes.

Finally, we need to synchronize the TOTP setup. To do this, the current TOTP token must be re-entered in the web service settings. The TOTP token can be copied in two ways:

• Control + T, or
• Right-click > TOTP > Copy TOTP

Go back to the web service settings:

• Paste the TOTP token
• Confirm

You should now see a message indicating that the setup was successful.

Backup

KeePassXC offers an automatic backup feature. This ensures that you always have an up-to-date version of your password database in a different “location” than the one you mainly use.

Under Settings (gear icon) > General > File Management, you will find the option Create backup of database before saving. There you can specify a path where the replacement file should be saved.

It may be a good idea to specify cloud storage if you are not already synchronizing the database via cloud storage.

Synchronization/backup in Nextcloud

At aktivismus.org you will find links to instructions for all platforms on how to synchronize files via Nextcloud.

The principle works the same with iCloud, OneDrive, Dropbox, etc.

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Nextcloud

Nextcloud is often used as a privacy-preserving alternative to Google Drive, iCloud or other commercial Cloud providers. Nextcloud is open-source software that can be installed (hosted) by anyone on their own server. Solidarity-based technology collectives sometimes operate their own “instances.” “Instances” are the individual Nextcloud installations, e.g., those of different groups/associations/companies, etc. Depending on the settings of the respective instance, the individual Nextcloud is completely “self-sufficient,” meaning it has nothing to do with other instances.

Nextcloud can also be an attractive tool for political groups to organize their work with shared passwords, calendars, documentation, pads, etc.

Account management

Source: https://wiki.systemli.org/howto/nextcloud/gruppen

If you want to use the cloud as a group, the problem arises as to which user owns the shared data (documents, calendars, deck boards, etc.). In most cases, we recommend the use of teams for groups.

Teams

• Each member of your group gets a personal account.
• In addition, you create a group account as an admin, which is managed by several people.
• Use the group account in the Collectives app (if available) to create a collective for the group.
  • Add all personal accounts under Manage members.
  • If necessary, grant admin rights to individual accounts.
    • Next to “Teams,” click on the “+” and add a description.

Now you have created a collective “team” (with the group account). From now on, you can share pretty much everything you do in Nextcloud with this team: files, calendars, Kanban boards (Deck app), polls, etc.

However, there is one thing to keep in mind: Ownership. All files (including calendars, Kanban boards, etc) always belong to the account that created them! Even if these resources (technical term) are then shared with the entire team, they still belong to the creator account.

The graphic above shows that the group account uploads a password database to its files and then shares this file with the team. They can then access this file.

This makes it easy to add or remove people from your team/collective later on. You don’t have to share all resources again for each new person. You can also easily pass on the administration of the admin account, and it’s no problem if the original admins become inactive.

Conversely, individual accounts can be removed from the team with a single click, so that they no longer have access to group resources.

Transfer ownership

If you ever lose access to the group account, you can transfer ownership of a file created from your personal account to the group account. Nextcloud provides its own instructions for this.

• However, the transfer must always be confirmed by the group account (to which ownership is being transferred) before it takes effect.
• Experience has shown that it can take a few minutes for the group account to receive the confirmation notification. You may therefore have to wait a little while.

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App passwords

Nextcloud allows you to create app passwords. This allows you to assign a different password to each device or app that you connect to your account. The advantage of this is that you can easily revoke access to your account for individual devices or apps from your account settings.

• Log in to the cloud and click on the avatar in the top right corner

• Select Settings > Security

Here you can create a new app password:

1. First, give the new password a name so that you know what it is used for later. Give each app password a unique name so you don’t accidentally revoke access to the wrong application. Here, we will call it “Sync Client.”
2. Click Create new app password

The password is now displayed for the first and last time! So make sure you copied the password to the application you want to connect with Nextcloud you before close the password window. In case you closed the password window too early, simply delete the lost password and create a new one instead.

The button Show GR code for mobile apps allows Nextcloud apps for mobile devices to log in once. In case you want to connect Nextcloud to a mobile application, this is more convenient then typing the password manually.

Here we can see the different “sessions” that can access our account.

Delete old sessions

Here you will notice that every time we log in to the browser and do not log out later using the Logout button, this “session” remains valid. This is a bit annoying, as we quickly lose track of whether these are our own “sessions” or whether, for example, an attacker has logged in in the meantime.

Here, for example, you can see that we did not log out properly 10 hours ago, but simply closed the browser window. The session is theoretically still valid, but no longer useful to us. So we delete the old session.

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Synchronize Nextcloud on devices

Nextcloud Sync Client

The Nextcloud Sync Client is Nextcloud’s own software for synchronizing content in the cloud with your own devices (PC, mobile phone, tablet). Installation and setup is very easy in most cases.

Content synchronization means that Nextcloud creates a folder on the device where all files from the cloud are stored. If a file in this folder is changed, it is changed directly in the cloud and thus also on all other devices linked to it. An example for the practical use of synchronization is described in the module Using KeePassXC as a group

Installation

• Download the software: https://nextcloud.com/install/#desktop-files

• Install Sync Client

Setup

• Login
• Enter the URL of your cloud instance (where you have an account)
• A browser window with the cloud login should then open

There are two options here:

1. Log in with your normal login details
2. For more security, log in with Alternative log in using app password with an extra app password!

Once we have logged in, a configuration window appears where we can specify which folders from our cloud should be synchronized with our computer. We can either select specific folders (Choose what to sync) or simply select all. Under Choose different folder, we can also specify where the synchronized Nextcloud folder should be located on our computer.

Depending on how much data we have in the cloud, the synchronization process may take a while. Once the synchronization is finished, we should have all our personal cloud files directly accessible on the computer in the specified Nextcloud folder.

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Create secure passwords with Diceware

Diceware is a method for generating passphrases/passwords using dice and a word list. These contain genuine randomness and, if sufficiently long, can be considered secure.

This tutorial briefly describes how you can create a secure password in just a few steps. Detailed instructions on Dice-Generated Passphrase can also be found on the EFF Website.

Concept

The idea is that you select different words for your password from a list of approximately 7,000 words. This gives you a password that is easy to remember and still contains real randomness. All you need is a dice.

Step 1

Select a word list in a language you are comfortable with. If your language is not in the list, you can find a word list by searching for “Diceware Wordlist” + “language.” Choose a list that is designed for at least five dice, i.e., contains at least 7776 words.

• dys2p/wordlists-en EN
• EFF’s Long Wordlist EN
• Website with other languages

For this example, we will use the EFF Long Wordlist. However, you can also use any other list designed for five dice.

Step 2

Now roll the dice five times and write down the results in the order you rolled them. For example: 14314

Now look up the word that matches this number in the word list.

In the EFF’s Long Wordlist the word corresponding to 14314 is bucktooth.

Step 3

Repeat step 2 at least six times.

You should now have six words. For example:

battery tacker horses blow counter note

Congratulations! You just created a secure and truly random passphrase!

Step 4

If there is no immediate danger of repression, write the password on a piece of paper and enter it once or twice a day. After one to two weeks, most people can remember their new password well. Then destroy the piece of paper!

There are different techniques for better remembering random passphrases. For some people, making up a story to go with the words can help to remember them better.

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Signal

Credit: The article is a translation of the LG Wiki Signal section.

Set up registration PIN

It is very important that you set up a PIN in Signal. This protects against unauthorized re-registration. Your network provider is required by law to forward SMS messages to the police. Without a PIN, the police can read your Signal messages – However, you would notice it if someone tries to re-register your device. Only one mobile phone can be registered with Signal, so you would be logged out of your Signal account.

To set up a PIN:

• iOS: tap your avatar » Settings » Account
• Android: Settings » Account » Registration Lock

Self-destructing messages

In individual chats/groups:

• Click on the name at the top of the chat
• “Self-destructing messages”

You can also set a default period of time for the feature to be automatically activated for new chats:

• “Settings”
• Privacy
• “Self-destructing messages”
• “Default expiration time” for new chats

Create usernames

Usernames make it possible to share your contact without revealing your phone number. For more information, see Signal’s blog.

• Settings
• Click on your mobile phone number at the top
• Set a username after the @

The username must end with a period and at least two digits, e.g.: username.12. However, there can also be more digits after the period.

Disable Find by phone number

You can prevent your Signal account from being found using your phone number. This will make it harder for people who know your phone number to find out if you are using Signal, which is important if you live in a country where Signal usage may be suspicious or illegal.

• Settings
• Privacy
• Phone number
• “Who can see my number”: Nobody
• “Who can find me by my number?” Nobody

Multiple Signal accounts on one device

There are various options for using multiple Signal accounts on one device. The options depend on your operating system:

Multiple Signal accounts on PC

The easiest way is to download the tool signal-account-switcher. This allows you to use four additional Signal accounts at the same time. To do this

1. Click on this link: https://github.com/kmille/signal-account-switcher/releases/tag/v0.1.0
2. Download the tool for your operating system. At the bottom of the page: “signal-account-switcher.exe” for Windows, “signal-account-switcher” for Linux and “signal-account-switcher-mac-{amd,arm}” for Mac (depending on your CPU).
3. Start the tool (Windows may complain at first because it is “unsafe” to run a file from the Internet) and simply click on “Start Signal Account #1.” A new signal-desktop instance will open.

If you don’t want to install an extra tool for using multiple signal profiles on your PC, you can also do it yourself with a little manual configuration:

• Instructions for Windows: https://www.youtube.com/watch?v=TejhH80jktE
• Instructions for Mac:
  1. open the command line/terminal
  2. paste the following command inside the terminal and hit Enter

mkdir $HOME/Library/Application/Signal-Account-1
/Applications/Signal.app/Contents/MacOS/Signal --user-data-dir=“$HOME/Library/Application/Signal-Account-1”

Multiple Signal Accounts on Android

Molly

There is a Signal fork called Molly, which can be installed alongside the normal Signal app and set up with a different account.

1. If you haven’t already, install F-Droid, a free and open source app store:
   • Download the F-Droid.apk file from the website.
   • Install f-droid by opening the .apk file you downloaded.
   • Allow “Installation of apps from unknown sources” when prompted.
   • Allow “Install apps from this source” if necessary.
2. Add Molly’s package source to your F-Droid by following these instructions on the F-Droid website. Molly is not automatically included in F-Droid and therefore needs to be manually added.
   • Go to https://molly.im/download/fdroid/ and select Molly (if you are reading this on your phone), or scan the QR code if you are reading this article on your PC. Select Molly, not Molly-FOSS, unless you know what you are doing (e.g., no Google Play services).
   • Open F-Droid and refresh once by swiping down from the top edge of your phone; this will load information about all available apps, which can take up to 2 minutes.
3. Install Molly via F-Droid
   • Search for Molly in F-Droid and install it. If necessary, allow “install from this source” for F-Droid again.

Molly is now ready and you can set up the app as you would normally set up Signal.

However, you will be asked at the beginning whether you want to use additional password encryption. Your choice cannot be changed later. This is useful for sensitive accounts.

Create a Signal PIN that you can remember for sure, or save it in your secure password manager, but don’t write it down on a piece of paper! This could be used by the police to intercept messages intended for you after a house search.

App clones

Some manufacturers offer a dual app feature to run multiple accounts on one phone. Search online to see if your device has this feature. Starting with Android 14, this option may be available by default on many devices.

You can also use this feature to clone Signal and Molly, which would enable you to use up to four different Signal accounts. You could also do without Molly and use Signal twice, but Molly is more useful because it has slightly better encryption and security mechanisms, which offer an advantage in the event of a house search.

You can easily activate the feature in the Android settings:

Samsung: Settings > Advanced features > Dual Messenger

Huawei: Settings > Apps > App Twin

LG: Settings > General > Dual App

A menu with all clonable apps should then appear, where you can simply select Signal (and any other apps you want to clone) and duplicate them.

Additional Android profiles

Android offers the option of creating multiple user profiles, just like Linux, MacOS, and Windows. For more information, visit the responding Android support page.

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System updates

One of the first answers to questions about IT security is always: Install updates. Since apps and systems should always be up to date, it is advisable to set automatic updates.

Depending on your operating system, you may need to distinguish between system updates and app updates. Where relevant, we explain the differences and provide step-by-step instructions on this page.

• Linux
• macOS
• Windows
• iOS
• Android

macOS

System updates on macOS

This updates the macOS operating system to the latest version. System updates on macOS will also update all standard apps such as Mail and Safari. However, apps installed via the App Store need to be updated separately

1. Click on the Apple icon in the upper left corner of the screen.
2. Select System Preferences from the drop-down menu.
3. Click on Software Update.
4. If updates are available, you can click on Update Now to download and install the updates.

App updates on macOS

1. Open the App Store on your Mac.
2. Click on the Updates tab in the sidebar.
3. Here you will see a list of available updates for the apps you have installed. Click on “Update All” to install all available updates.

Automatic updates on macOS

Go to Software Update as described above and enable Automatic Updates to ensure that your system is always up to date. There is a small arrow next to Automatic Updates. Underneath it, Download new updates in the background and Install app updates from the App Store should be enabled.

Windows

In Windows, it is important to distinguish between system and app updates, mainly because all programs installed after the initial installation have their own individual update mechanisms. This means that in Windows, you must regularly check for updates for each program installed. This information can usually be found somewhere in the settings of the respective program.

System updates on Windows

1. Click on the Start menu (Windows logo) and select the gear icon for Settings.
2. Click on Update & Security (Windows 10) or Windows Update (Windows 11).
3. Click on the Check for updates button.
4. If updates are available, click on Install updates.
5. Click on Restart now if a restart is required to complete the installation.

Automatic system updates on Windows

• Go to the update settings as described above
• Click on Advanced options
• Enable Download updates automatically

Linux

In most cases, system and app updates on Linux can be considered as the same thing. Depending on the Linux distribution, the individual settings may vary slightly, but the principle is the same everywhere.

Ubuntu (including: Debian, Mint, PopOS,…)

System updates can be performed in two ways: via desktop programs similar to the App Store, or directly with a command in the terminal. In fact, modern versions of Ubuntu should be preset to perform all updates automatically. However, this should be checked. If in doubt, take a look here.

Updates via the desktop app

• Search for Software Updater

Updates via terminal (Ubuntu)

1. Open the terminal (Ctrl+Alt+T, or search for “Terminal” in the app menu)
2. Paste the following command into the terminal (right-click, Paste)

sudo apt update && sudo apt upgrade -y && sudo snap refresh

Automatic updates (Ubuntu)

In GNOME:

• Open “Software & Updates”
• Open the Updates tab
• Under “When security updates are available,” select the “Automatically download and install” option

Fedora

System updates can be performed in two ways: via desktop programs similar to the App Store, or directly with a command in the terminal. Modern versions of Fedora usually enable automatic updates by default. However, It is best practice to check if this is the case.

Updates via the desktop app (Fedora)

See Ubuntu

Updates via terminal (Fedora)

1. Open the terminal (Ctrl+Alt+T, or search for “terminal” in the app menu)
2. Paste the following command into the terminal (right-click, Paste)

• sudo dnf update

Upgrade to new Fedora version (about once a year)

To update to a higher version of Fedora, refer to the official documentation from the Fedora Project.

Automatic updates (Fedora)

See above under Ubuntu.

Tails

Tails comes with its own Tails Upgrader, which automatically checks for updates and installs them. However, this requires that the system is running long enough to complete the updates. So check again before shutting down to see if any updates are available. (Open Tails Upgrader in the app menu)

It is recommended to manually upgrade your Tails installation every few months. This is slightly more secure, and will decrease the time needed for future updates. For concrete instructions, go the Tails documentation.

iOS

System updates on iOS

1. Open the Settings app
2. General
3. Software Update: This will check for available updates.
4. Download and Install. You may need to enter your password.
   • Accept the terms of use when prompted.
   • The update will be downloaded and installed. Your device may restart during the installation process.

App updates

1. Open the App Store
2. Go to Updates
   • Tap your profile picture or the Updates icon in the lower right corner.
3. Tap Update All to update all apps.

Enabling automatic updates

For system updates

1. General
2. Software Update
3. Here you will find the option Automatic Updates. Enable this option.

For app updates

1. Open the Settings app
2. Apps (usually at the bottom)
3. App Store
4. Enable App Updates

Android

The exact names of the menu items may vary depending on the manufacturer of your Android device, but the principle is the same across all devices.

System updates on Android

1. Open the Settings app
2. At the bottom, tap About this phone or System
3. Software update or System updates
4. Download or Install. You may need to enter your PIN or password.

Automatic system updates on Android

Automatic system updates are usually enabled by default on Android. They are only accessible via the Developer Options, which should not be touched unless you know exactly what you are doing.

GrapheneOS

In theory, the above also applies to “normal” Android versions, but the following usually applies to GrapheneOS users:

If you don’t use your “Owner” profile regularly and are mostly in a user profile, the auto-updater (which only works in the Owner profile) may not always check for updates.

For all users: switch to the owner profile regularly and follow the manual method described above.

App updates on Android

Since different app stores are used here, we will simply list them all in order. While auto-updates are usually enabled by default for all of App Stores, it is best to confirm this manually.

Google Play Store

1. Open the Google Play Store
2. Go to “My apps and games”
3. “Update all”

Automatic updates in Google Play Store

1. Open the Google Play Store
2. Under the user icon, tap Settings
3. “Network settings”
4. “Enable automatic app updates”

Automatic updates in Aurora Store

1. Tap the gear icon in the top right corner
2. Tap “Settings”
3. Tap “Updates”
4. Tap “Auto-update apps”
5. Select “Install automatically.”

Automatic updates in F-Droid

• Settings
• Automatic update interval
  • Here you can set how often to check for new updates. (e.g. daily)
• Activate Install updates automatically

Automatic updates in Accrescent

• Settings
• Activate Automatic updates

Automatic updates in Obtainium

• Settings
• Enable background updates
• For faster updates: Allow parallel downloads

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VeraCrypt

The software VeraCrypt is required for all methods mentioned here. This means that this program must be installed on your PC in order to encrypt and decrypt (reopen) encrypted storage, such as folders or USB sticks.

Encrypt entire hard drives/USB sticks or folders with VeraCrypt

There are two main ways to encrypt an entire USB stick or hard drive:

1. Create and encrypt a folder that is as large as the entire storage medium.
2. Encrypt the file system of the hard drive itself.

Because a lot can go wrong with option 2, we generally recommend option 1. This should not have any disadvantages. This also means that with option 1, the process for encrypting individual folders or the entire USB stick/hard drive is identical.

However, if the device to be encrypted is formatted with FAT32 and is larger than 4 GB, this will not work, which is unfortunately often the case.

If your storage medium has this type of formatting, it must either be reformatted for option 1, which requires other software, or option 2 must be selected.

From now on, we will describe both options in parallel. If there are differences between the two options, they will be marked with the headings “Option 1” or “Option 2.” The rest applies to both options.

Open VeraCrypt

• Click on Create Volume

Option 1: Create file for encrypted container

The encrypted “folder” is actually just a file, called a container in VeraCrypt. We can only use it later as a normal folder when it is opened and decrypted via VeraCrypt.

• Here, we select a “Encrypted file container”: Next>

• Then select Standard VeraCrypt Volume and Next>

Under the Location menu, we now select the location where VeraCrypt should store the container for us. This should, as said, be our USB stick/hard drive.

• Fist click Select File
• This will open the file manager. Navigate to the USB stick/hard drive that you want to encrypt.
• Now we create the container, which will later become our encrypted folder. Enter a name for the file in the field provided. The name is technically irrelevant, but it will be the name of the file that you will see later when you simply insert the stick and open it.

• Confirm with Save

Option 2: Encrypt the entire file system

• Standard VeraCrypt Volume > Next>

Now we have to select the storage medium.

It is usually helpful to look at the storage size to identify the correct stick. If you want to encrypt a hard disk that may be the same size as other connected storage media, you must look at the path/mount points, which can include the name of the device. In the above screenshots you can see two devices with 3 and 1 partitions: nvme0n1* and sda*. The listings directly below them are their separate partitions.

For example here, the upper nvme0n1 device is a 1.8TB (~2TB) large SSD, while the lower sda one is a 29,3GB (~32GB) USB drive.

If you are still not sure which device or partitions is the correct one, remove the device you want to encrypt and check the list again. The ones that still show up, are not the right ones!

• Once you are sure which device should be encrypted, confirm the warning that all files on the selected device will be destroyed.

Encryption Options

The default settings should suffice. Explaining the technical details would go beyond the scope of this guide. If interested, you can read more about the different encryption algorithms here.

• Click Next>

Option 1: Volume Size

Here we specify how large the container (folder) should be later. You can choose any size depending on the amount of free storage space available.

Option 1: Folder as large as the entire stick

As you can see in the image above, there is an extra checkbox to use all available space for creating the container (folder).

A warning appears stating that files larger than 4 GB cannot be stored on FAT32. You can simply click OK here, if you made sure, that your drive is not formatted as FAT32.

Set password

Here you can set the password that will be used to encrypt the container. You should choose a strong password, otherwise it can be easily guessed.

It is best to generate and save a password using a password manager such as KeePass:

File system settings

Now we are asked whether we want to store files larger than 4GB in our folder.

If you are sure that you do not want to do this, click no, otherwise click yes. Next, a file system must be specified.

• Select exFAT if you want to use the storage on Windows computers.
• Select ext4 if you only want to use the storage on Linux and MacOS.
• Select NTFS if you only want to use the storage on Windows and Linux. Although NTFS is not made for Linux itself, Linux can handle it fairly OK.

The respective platforms may be able to handle all formats, but these recommendations should work without any problems.

Quick Format

The checkbox next to Quick Format is usually only available for option 2. It means that the storage will not be overwritten with random bits during encryption. The advantage of this is that, especially for large data carriers, the encryption process is extremely shortened and only takes a few seconds.

However, this also brings uncertainties with regard to security, which is why we only select this option if:

• No sensitive data has ever been stored on this storage medium. (Never really means never, see Data hygiene), or
• The storage medium is already encrypted, its password is not known to any adversary, and it is only being encrypted “again” (for whatever reason).

Next, specify whether you want to use the storage medium on operating systems other than your current one (if in doubt, always select this option, just in case).

Random generator

The “Random generator” window will now open. Without going into further detail, it should be noted here that good encryption depends on randomly generated data being “mixed in” with the encryption.

Since computers are not perfect at this, VeraCrypt asks you to make random movements with your mouse in the window. This slowly fills the blue bar under “Randomness Collected From Mouse Movements.”

The bar should be at least half full. The more the better!

• Click Next> once the bar is full enough

Encryption process

VeraCrypt now begins to encrypt the file in the specified size and with the selected settings. To do this, it first writes random “ones” and “zeros” to the entire container (unless Quick Format is selected). Depending on its size and speed, this can take from a few minutes to several hours.

Change password later

You can also change the password of a VeraCrypt container later.

• Mount container

• Click Change Volume Password

• Enter the old password at the top and the new password twice at the bottom. _(Tip: Generate and save passwords with a password manager)

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Installing VeraCrypt

Downloading the installer file

To install VeraCrypt, you must first download the appropriate installer file. Installer files for various operating systems are available on the VeraCrypt website.

Verifying the installer file

Before installing VeraCrypt, it is important to verify the authenticity and integrity of the downloaded installer file. Integrity means that the file has not been damaged or tampered with during the download. Authenticity means that we downloaded the file from the intended source and not from someone posing as VeraCrypt. The verification is done using two verification techniques: checksums and PGP/GPG signatures.

Installing PGP

For the next steps, we need to install a program that can handle PGP signatures. This is already pre-installed on Linux. For Windows, it must be downloaded here and installed. For MacOS, homebrew can be downloaded and installed.

Downloading, verifying, and importing the developers’ public key

First, we need the developers’ public PGP key. This allows us to verify that the signature of the download file is correct. The public key can be downloaded here and saved under Downloads. Now you need to check that you have downloaded the correct key by comparing the public key fingerprint (a unique identifier for a key). To do this, open a CMD window in Windows or a terminal in Linux/macOS and enter the following:

cd Downloads
gpg VeraCrypt_PGP_public_key.asc

The fingerprint (36-digit number) that is displayed must match the one on the Veracrypt website. If it does, the key is correct and can be imported. To do this, go back to the CMD window in Windows or the terminal in Linux and enter the following:

gpg --import VeraCrypt_PGP_public_key.asc

Make sure that you are in the folder or directory in which the public key is stored, e.g. Downloads.

Download the signature from VeraCrypt

Now we need to download the signature matching the installer file from the VeraCrypt website and to save it in Downloads. It is important to download the signature that is directly behind the installer file you downloaded earlier.

Checking the signature of the installer file

Now we use the signature and the public key to check whether the installer file is complete and was actually downloaded from the VeraCrypt developers. To do this, open a CMD in Windows or a terminal in Linux/macOS and enter the following (replace the placeholders in [] with your actual file names):

gpg -verify [full name of the signature file] [full name of the installer file]

For example: gpg --verify veracrypt-1.26.20-Ubuntu-24.04-amd64.deb.sig veracrypt-1.26.20-Ubuntu-24.04-amd64.deb

The output should now read “Signature OK from ‘VeraCrypt Team (2018 - Supersedes Key ID=0x54DDD393) veracrypt@idrix.fr’ [unknown]”. The installer file is now trusted and can be installed. You can ignore the warning that the key does not have a trusted signature.

VeraCrypt Installation Process

Double-click on the installer file to install VeraCrypt.

Updating VeraCrypt

In some cases, VeraCrypt may prompt you to update automatically, which is the preferred update process since it is quick and simple.

If VeraCrypt does not ask to automatically update, a manual update works in the same way as the above. You need to download the installation file, verify it, and then install it again, replacing your outdated version. This should be done every time a new version is available.

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Seizure of devices

After seizures, there is often a lot of speculation about what information could potentially be found on the devices. In these moments, we remember all the little “security sins” we have committed over the years: photos, chats, contacts, etc. that were not deleted.

The shock often hits hard and is mixed with concern about what the rest of the group will say when they find out that our mistakes could now cause problems for them too.

It is precisely at these moments that we ask ourselves:

That’s exactly what this module is about:

Prevention

We should think carefully about the following things in advance, as they can save us a lot of stress afterwards.

Encryption

• Are the devices encrypted?
• Are they encrypted with strong passwords?
• Are all storage media such as USB sticks, hard drives, and SD cards encrypted with strong passwords?

Passwords

• Are all passwords stored securely in a password manager?
• Is there a current backup of the password database in a secure location, so that you can recover easily, when your daily password database get’s confiscated?
• Are there any passwords written down on paper lying around somewhere? If so, destroy them.
• Have you set up two-factor authentication on at least all important accounts? Especially email accounts, because they can often be used to reset passwords from other services, that you used this email for.

Data hygiene

The less data you accumulate, the less data can be seized from you: Read the article on data hygiene:

Signal

In Signal, you should definitely:

• Set disappearing messages be set (e.g. 1 week) so that as few chats as possible are stored on the device at any given time.
• Deactivate the option finding by phone number.
• Set the registration PIN.

Backups

Confiscation means: devices and data are gone. Can you “recover” from this loss as quickly as possible, i.e., restore your data to other devices?

Making backups is annoying, but without them, you and others could suffer significant damage. Sometimes, years of work are lost because essential data/results were confiscated and there was no backup strategy.

Turn off devices

Devices are only properly encrypted when they are turned off, because after they are unlocked for the first time (immediately after booting up), the encryption key is stored in the device’s RAM.

Therefore, try to turn off your devices, before they get confiscated. House searches often happen at night, or very early in the morning. Setting up auto reboot for all you devices ensures that they will be secure at every morning!

Follow-up

Now the devices have been seized and are out of reach. Have all of the above points been taken into account? If yes - Good job! But what if not?

In any case, you should contact a lawyer as soon as possible and tell them about what happened. We are not lawyers and therefore cannot give legal advice. You should also discuss the following points with them if possible.

Evaluation

• Who should you report this to?
• Has your account been removed from all chat groups by your comrades so that the authorities cannot read your messages.
• Change problematic group names in Signal as quickly as possible. Only that the name has been changed will be visible, but not what the group was called before. This may be useless for other messengers.
• The above last two points will only work as long as the device still has a network connection, but it doesn’t hurt to try.

• Change the relevant passwords - If you haven’t already done so, set up two-factor authentication to prevent the authorities from accessing your accounts with your password.

Restore backups

Now you will want to get your data back, which will be no problem, if you’ve made your backups regularly.

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Using KeePassXC as a group

KeePassXC is not actually cloud software, which is one of the reasons it is so popular - none of your passwords ever leave your own computer. However, this makes it impractical for managing different logins as a group. Every time a change is made to the database, (new password added, password changed, etc.) everyone has to be notified of the changes so that they can apply them locally.

However, similar to cloud-based password managers such as Bitwarden, we can also keep a KeePassXC database automatically synchronized across different computers, while still opening and editing the database as usual with KeePassXC.

This requires a working cloud environment for your group to be set up. We would recommend Nextcloud, as it’s not only open source, but is also hosted by various very nice tech collectives, meaning you don’t have to set NextCloud up yourself. See our instructions on Nextcloud groups and device synchronization for more information on using NextCloud.

After successful installation and setup, each member of your group should have direct access to all of your cloud files locally, i.e. directly on the computer.

Sharing the password database (and other files)

Now, the group password database, hereinafter referred to as “the database”, is uploaded from the group account to your own files:

Share file

• Click on the Share icon (or on Details under the three dots):

• Enter the name of the team in the search field and select the team (the name may need to be written out in full):

• Give the group editing rights (otherwise the team members will not be able to edit the file, which is necessary, if they should be able to add, or change passwords e.g.):

Here you can now see who has access to this resource:

All team members should now have access to this database in the files of their own accounts. (See this graphic, that explains how shared files are accessed from different accounts)

Open shared database

• In KeePassXC, select Open database in the bar at the top left.

• In the window that opens, select the shared database from the Cloud folder.

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Role-playing game about transport and E2E encryption and MITM

This game aims to illustrate the process, but not the functionality, of network communication using the example of emails without encryption, with transport encryption, and with end-to-end encryption. It is not really a game that is meant to be fun, but rather a means of explaining the topic without having to use a network diagram, thus making it more accessible to less technical people.

Roles

• 2x servers (systemli.org & gmail.com)
• 2x communication parties (Alice & Bob)
• 1x (or more) police officers (Eve)
• 3x “The Internet” [optional]

Materials

• 1x sheet of paper for text
• 1x sheet of paper with email metadata
• 3x sheets of paper with IP metadata for the routes between the nodes
• 2x signs with the names of the servers
• 2x signs with the email and IP addresses of the communication parties
• 1x small box that can be locked with a padlock (large enough to hold the sheet of paper with the text)
• 3x large boxes with lids (large enough to hold the other box)
• 2x padlocks
• 3x chairs

Ideally, the sheets should be laminated and written on with whiteboard markers. This way, they can be easily reused.

Procedure

In preparation, the Internet metadata information is stuck on each of the large boxes.

Then the roles are assigned. The role of the police should preferably be played by someone without much technical knowledge, so that creativity is required for the attacks. The rest of the people watch.

The two servers and two communication parties stand in a square. The servers and communication parties are given the signs with their information.

One chair is placed between each of the four people, on which one person playing the internet sits. They are also given the box with the corresponding internet metadata.

Alice writes a message to Bob on the sheet for the text and fills in the metadata that is not already filled in on the sheet with the metadata.

Now the various scenarios are played out. Each scenario is shown once without MITM and once with MITM (in our case by the police). The role of the police is to come up with their own ideas on how to attack the scenario. The only exceptions are attacks on Alice and Bob, which are not the aim of this game. Furthermore, the legality of the attacks or whether the parties would hand over the data to the authorities is not discussed; all technically possible attacks can be considered. The police can only attack the internet and the servers.

If the police cannot think of any way to attack, the audience can help. If they also have no ideas, the moderator can help.

The audience should then explain what happened, whether the attack worked, and what data the police obtained.

Unencrypted

Anna gives the sheets with the text and the email metadata to the Internet, which gives them to the first server, which sends them back to the Internet, which sends them to the second server, which sends them back to the Internet, which finally sends them to Bob. At each node, the sheets are placed in the box with the corresponding IP metadata.

Unencrypted - MITM

Possible targets of attack are:

• The internet
• The servers

All data can be intercepted at both points.

Transport encrypted

This time, the boxes are “locked” with lids. Although these boxes are not locked in the game, it is pointed out that they should still be considered secure. However, they only provide protection during transport; the nodes must be able to open the corresponding boxes.

Otherwise, it works the same as in the unencrypted scenario. It is important to ensure that both sheets are taken out of the box at each node and then placed in the appropriate other box. This is necessary because the servers need the metadata to know where to forward the mail.

Transport encrypted - MITM

Possible targets for attack are:

• The servers

All data can be intercepted there.

End-to-end encryption

First, it is explained that end-to-end encryption involves a public key and a private key. We represent the public key as a padlock and the private key as the key for the lock. It is briefly pointed out that this public key must be exchanged in such a way that it is certain that it belongs to the person. For this scenario, we do this by having Bob go to Alice in person and give her the padlock.

Alice puts the piece of paper with the text in the small box, locks it with the padlock, and puts this box together with the sheet containing the metadata in the large box. She then sends it to the Internet. After that, the process is the same as before: the large box is unpacked and repacked at each node, and the small box is finally opened at Bob’s end.

End-to-end encryption - MITM

Possible targets for attack are:

• The servers

Only the metadata can be accessed there.

End-to-end encryption with TOFU

This time, the public key is exchanged as usual by email without being verified.

1. Alice writes to Bob, “Send me the key.”
2. Bob sends the key.
3. Alice writes end-to-end encrypted as above.

End-to-end encryption with TOFU - MITM

Possible targets of attack are:

• The servers

All data can be intercepted there.

The attack proceeds as follows:

1. Alice writes to Bob, “Send me the key.”
2. Bob sends Alice the key.
3. The police intercept the key and replace it with their own.
4. Alice encrypts the message with the police key.
5. The police intercept the message and read it.
6. The police re-encrypt the message with Bob’s actual key and send it on.

Neither Alice nor Bob are aware of the attack, but the police can read everything. Because the key was replaced by the police, a second padlock is required here.

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