General Safety Advice[edit]

It is recommended to review the Do not Mix Anonymity Modes section in conjunction with this entry. For a comprehensive comparison of instant messengers, see here ^[archive].

Encryption[edit]

Tor exit relays can eavesdrop on communications if encryption to the server is disabled. Depending on the protocol, encryption might be disabled by default or not even supported. Tails has noted that without encryption, the exit relay can see the contact list, all messages, file transfers, and audio/video. ^[1] While encryption to the server prevents exit relay eavesdropping, it still leaves one problem unresolved: server logging.

High-risk users should also bear in mind that even in the event that strong and secure end-to-end encryption is used -- for example encrypted chat using .onion connections only (staying within the Tor network) -- sophisticated attackers (nation state actors) are capable of compromising the trusted computing base (TCB) ^[2] of nearly all platforms: ^[3]

All proper end-to-end encrypted (E2EE) messaging systems store private key(s) exclusively on user's device (endpoint). The holy grail of attacks against E2EE systems is called exfiltration where the sensitive data, namely the private keys or plaintext messages, are stolen from the endpoint. The attack is directed against the trusted computing base (TCB) of the target system. The overwhelming majority of TCBs are connected to the network and compromising them with polished malware that exploits a zero-day vulnerability, is trivial and undetectable.

Another consideration is that even when using end-to-end encrypted applications, additional strong security protocols such as forward secrecy ^{[archive] [4]} may not be available for group communication channels, see: More is Less: On the End-to-End Security of Group Chats in Signal, WhatsApp, and Threema ^[archive].

Server Logging[edit]

Encrypted server connections do not prevent the server gathering interesting information about users, such as common contacts and the regularity of communications. An example list includes:

• account names
• buddy list (list of contacts)
• the exact date and time of logins
• message timestamps
• communication patterns like common contacts (see footnote) ^[5]

The content of messages will only be protected by using end-to-end encryption, for example OMEMO ^[archive]. The threat of server logging can be completely removed with decentralized (server-less) instant messengers like OnionShare.

Jabber / XMPP[edit]

Jabber/XMPP ^[archive] is a libre server-federation protocol designed with openness in mind: "... All of the existing XMPP servers, clients, and programming libraries support the key features of an IM system, such as one-to-one and multi-party messaging, presence subscriptions and notifications, and contact lists."

The system is decentralized because there is no central authoritative server; anyone can run a server. Some users are confused on this point because there are a number of large and popular public XMPP servers (like jabber.org), to which many have subscribed. ^[6] Each network user has a unique XMPP address called a JID (Jabber ID). The JID is similar to an email address insofar as it has a username and domain name like username@example.com ^[7]

Safely using the protocol requires proper use of encryption (such as OMEMO), because it is unwise to trust server connections are properly encrypted between each other. Jabber privacy is also limited, as various adversaries are capable of observing which accounts are communicating. Jabber and Tor combined only guarantee pseudonymous communications, as while the user's current location is hidden, the social graph can still expose their true identity. For tips on operational security when chatting anonymously, see this article ^[archive] by The Intercept ^[archive]. Also see: Why prefer open protocols such as Jabber/XMPP over proprietary ones such as ICQ? ^[archive]

IRC[edit]

When using IRC inside Whonix-Workstation ™, the Ident Protocol ^[archive] is automatically blocked because Whonix-Workstation ™ is firewalled. Therefore the associated daemon will not identify the username which is linked with a particular TCP connection, as is normally the case.

The Tor Project Internet Relay Chat ^[archive] page contains a number of important recommendations and tips for safe IRC use:

Recommendation[edit]

Applications discussed in this chapter are listed in order of best usability and compatibility with Whonix ™, based on the opinion and experience of Whonix ™ developers.

It should be noted that no single application listed here has a superior feature set. Users must make a choice based on personal preferences and their self-assessed threat model:

1. Dino IM is the best option currently. It provides the best UX, a modern and clean look and OMEMO support.
2. Gajim has more Jabber users, is written in memory-safe python, supports offline messages, and can provide OMEMO-grade encryption. On the downside, it requires a Jabber server which weakens anonymity.
3. HexChat is an open source IRC client based on XChat (therefore not technically an instant messenger). It has better usability and supports encrypted plugins like OTR, but on the downside it relies on centralized IRC servers.
4. OnionShare provides a secure, ephemeral and anonymous chat feature. It is particularly useful because it does not require account creation, is encrypted end-to-end and reduces the risk of messages being stored locally.
5. Quaternion is a libre Matrix desktop client that can be used for Telegram and IRC channels.
6. Nheko Reborn is another desktop IM client for the Matrix protocol and can be used for IRC channels. The developers do not recommend it as a daily driver due to possible implementation bugs.

Dino IM[edit]

Overview[edit]

Dino IM ^[archive] is a modern XMPP ("Jabber") Chat Client written in GTK+/Vala for GNU/Linux and is available in Debian. OMEMO is supported, but needs to be toggled in the chat window. OpenPGP is also supported.

Installation[edit]

sudo apt update

sudo apt full-upgrade

sudo apt install --no-install-recommends dino-im

Dino IM is planned for inclusion by default in Whonix ™ 16. One outstanding issue at present is broken OMEMO compatibility with Gajim users.^[12]

Key Backup[edit]

In addition to the fingerprint displayed in clients, OMEMO uses session/ephemeral keys: as soon as you chat with someone, these keys are created and they are replaced with new ones after every message exchange.

Without the latest session keys, incoming messages cannot be decrypted. This means when session keys are imported from an older backup, problems are likely if the keys were used in between.

Both types of keys are stored in ~/.local/share/dino/omemo.db (a SQLite database). Problems are avoided so long as keys are not backed up while Dino is running and Dino is not started from the same database twice.

Gajim[edit]

Overview[edit]

Ubuntu provides a succinct overview of Gajim: ^[13]

Gajim is a free software, instant messaging client for the Jabber (XMPP) protocol which uses the GTK+ toolkit. It runs on GNU/Linux, BSD and Windows. The name Gajim is a recursive acronym for Gajim (is) a jabber instant messenger. The goal of Gajim is to provide a full featured and easy to use Jabber client. Gajim works nicely with GNOME, but does not require it to run. It is released under the GNU General Public License.

Gajim has various features, including: ^[14]

• chat client synchronization
• group chats
• sending of pictures, videos and other files to friends or groups
• secure end-to-end encryption via OMEMO or PGP
• the option to keep and manage all chat history
• connection compatibility with other messengers via transports, such as IRC
• various other features are available via plugins

In 2021, audio/video is reportedly not functional in Gajim. Further, OTR support was dropped in Gajim release 1.0, but the OMEMO plugin ^[archive] is an encryption alternative. ^[15]

Figure: Gajim Client in Whonix ™

Installation[edit]

The steps below install Gajim, along with the OMEMO encryption plugin and HTTP Upload plugin ^[archive] (which is required for file transfers). ^[16] The latter plugin is fully integrated into the core Gajim software as of version 1.0. Upon first launch of the program, users can use an existing XMPP account or create a new one.

Update the package lists.

sudo apt update

Install gajim and gajim-httpupload. ^[17]

sudo apt install gajim gajim-httpupload

Start Gajim from the start menu or type in konsole.

gajim

^[18]

Configuration[edit]

Account[edit]

On first launch, an Account Creation Wizard Dialog will appear. Use the wizard to either create a new account to connect to the jabber network or use an existing account. For new accounts, there are multiple jabber servers available and only a username and password is required to join. ^[19]

Gajim Settings[edit]

The following changes are recommended for better security and privacy.

Gajim cannot be installed by default in Whonix ™ yet, as there is more development work TODO; see Dev/Gajim.

HexChat: IRC Client[edit]

See HexChat.

OnionShare[edit]

See OnionShare.

Quaternion[edit]

Overview[edit]

Quaternion is a Qt-based desktop IM client for the Matrix protocol. Matrix is an open, federated communications protocol. ^[24]

To connect to other Matrix users and/or the Whonix ™ Telegram channel without dealing with Telegram Desktop, it is possible to create an account on the tchncs.de ^[archive] or privacytools.io ^[archive] home server for a more private experience; less data is collected about users compared to the matrix.org home server. The privacy issues are inherent in the synapse server side software itself; refer to this list ^[archive] for a full write-up. Besides federating with other Matrix instances, Quaternion supports bridging to IRC, Telegram and many other protocols. ^[25]

Installation[edit]

sudo apt update

sudo apt full-upgrade

sudo apt install --no-install-recommends quaternion

Nheko Reborn[edit]

Overview[edit]

Nheko Reborn is: ^[26]

... a Qt-based chat client for Matrix, an open, federated communications protocol. The motivation behind the project is to provide a native desktop app for Matrix that feels more like a mainstream chat app and less like an IRC client.

The developers explicitly warn that although the current implementation of end-to-end encryption is functional, it may have bugs that affect security. Further, it may be necessary to bootstrap cross-signing keys in a different client. Online key backup is not supported, but this can be performed offline. Most major chat features are available such as: VoIP calls (voice and video); user registration; creating, joining and leaving rooms; sending and receiving invites/files/emojis and so on.

Refer to the Nheko Reborn GitHub README ^[archive] for further information.

Installation[edit]

sudo apt update

sudo apt full-upgrade

sudo apt install --no-install-recommends nheko

Web Browser / JavaScript Clients[edit]

Web clients can provide weaker or stronger security depending on the user's threat model.

One disadvantage of web clients is that they rely on the server not attacking the user and stealing their encryption keys from the browser. Websites can target specific users with malicious JavaScript whereas with an installed application, the code is completely static. ^[27]

Furthermore, installed applications can utilize TLS certificate pinning to better mitigate man-in-the-middle attacks by eliminating the dependence on potentially compromised certificate authorities. Certificate pinning is already being extensively used by applications such as Signal ^[28], ProtonMail ^[29] and others.

In addition, the stateless design of Tor Browser will erase any keys created and approved by communicating parties. This can cause confusion about the trustworthiness of contacts in subsequent sessions -- one workaround is to use a dedicated install of Firefox for that purpose.

However, there are advantages to web clients too. Websites are much less privileged than installed applications and have no direct access to system resources. Common browsers also often employ browser sandboxing technologies to contain malicious websites even in the event of a browser exploit (unless chained with an additional sandbox escape exploit).

Element Web[edit]

Element Web App ^[archive] is a browser-based Matrix client. It can also be run from different platforms ^[archive].

Converse.js[edit]

Converse.js is an OMEMO browser client ^[archive] which is provided by some XMPP hosting services. However, chat encryption is only available on "Trusted Devices".

Deprecated Chat Clients[edit]

The following is a list of chat clients which were previously documented on this page. It is not a list of all deprecated chat clients that have ever existed.

CoyIM[edit]

CoyIM is no longer included in Whonix ™ due to technical issues. Namely, it is currently not available from Debian stable or backports package sources (packages.debian.org). ^[30] There is a chance it will be reintroduced when Whonix ™ 16 (based on Debian bullseye) is released. Manual software installation might also be possible (see Install Software), but that procedure is undocumented by Whonix ™ developers.

Nheko[edit]

The original Nheko application is no longer maintained and was last worked on in 2018. ^[31]

As an alternative, consider installing Nheko Reborn.

Pidgin[edit]

Pidgin supports most protocols and OTR end-to-end encrypted chat. However, it is not recommended because it has a very poor security record ^[archive] with many remotely exploitable bugs. Security researcher and developer Micah Lee notes this is the result of reliance on legacy protocols and the libpurple, libotr and libxml libraries which are: "... massive, written in C/C++, and are littered with memory corruption bugs. ..." ^[32]

RetroShare[edit]

Whonix ™ developers no longer list RetroShare, which is a friend-to-friend ^[archive] (peer-to-peer), decentralized network and not an anonymizing network. Encrypted RetroShare connections support chat, voice and video, mail, file-sharing, forums and Tor. ^[33] Although RetroShare is under active development ^[archive], ^[34] there are several serious concerns which disqualify a recommendation:

• The RetroShare package is signed with weak 1024-bit keys (in late-2018).
• A 2016 code review which focused on implementation vulnerabilities discovered multiple security issues: ^[35]
  • The attack surface is high due to the feature-rich codebase.
  • Systemic "insecure coding practice" was identified, particularly "...inconsistent return value checking and error handling, poor usage of explicit and implicit typecasting, and relaxed handling of adverse security edge-cases."
  • Within a 24-hour period, auditors had developed proof of concept exploits for web-like vulnerabilities, weak binary protections, and out of bound memory reads and remote memory corruption (promptly rectified by developers).
• A coverity scan of the RetroShare code shows a large number of outstanding defects, along with a relatively high defect density. ^{[36] [37]}

Ricochet IM[edit]

Ricochet IM is unsupported since it was broken in Whonix ™ 15 despite all efforts to fix it ^[archive]. Riccochet's functionality in Whonix ™ 16 is yet to be formally tested.

Interested readers are most welcome to experiment with Ricochet IM to try and fix the problem -- refer to the archived documentation here.

TorChat[edit]

TorChat has not been recommended by Whonix ™ developers since late-2015. The reason is development has been at a standstill ^[archive] since 2013 and the TorChat developer does not respond to other people, suggesting the project has been abandoned. TorChat is also an unofficial project and unaffiliated with The Tor Project. Since communication, support, active development and security fixes are essential for anonymity-related projects, modern software alternatives are recommended. ^[38]

Another reason to avoid TorChat is the findings of a 2015 security analysis ^[39] which inspected the protocol and Python implementation: ^[40]

It was found that although the design of TorChat is sound, its implementation has several flaws, which make TorChat users vulnerable to impersonation, communication confirmation and denial-of-service attacks.

Tor Messenger[edit]

Do not use Tor Messenger! It was deprecated by upstream developers in early-2018. ^[41]

Tox[edit]

qTox has been removed from Whonix ™ ^[archive] due to serious security issues.

Other Software[edit]

For anonymous Voice over IP (VoIP) or encrypted, anonymous phone calls using the Tor anonymity network, see: VoIP.

If a messenger program is not listed in this chapter, it is for now recommended against. If readers feel any privacy-respecting chat clients are missing on this page, first search the Whonix ™ forums ^[archive] to see if that application has been discussed in the recent past. Any additions to this page will be based on an objective analysis of the software's underlying strength and compatibility with Whonix ™. ^[42]

Footnotes / References[edit]

License[edit]

Whonix ™ Chat wiki page Copyright (C) Amnesia <amnesia at boum dot org>
Whonix ™ Chat wiki page Copyright (C) 2012 - 2021 ENCRYPTED SUPPORT LP <adrelanos@whonix.org>

This program comes with ABSOLUTELY NO WARRANTY; for details see the wiki source code.
This is free software, and you are welcome to redistribute it under certain conditions; see the wiki source code for details.

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