Introduction[edit]

Trust is a very problematic issue. This is the essence of why security is difficult in every field, including general computing and Internet communication. A skeptical user might ask themselves the following questions before relying upon Whonix ™ for sensitive activities on a daily basis:

• Can Whonix ™ and its developers be trusted?
• Are backdoors present in Whonix ™ that can take control over a computer or exfiltrate data?
• Does Whonix ™ generate compromised encryption keys to enable government spying?
• How trustworthy and sincere are the stated anonymity goals of the Whonix ™ project?

Opinions will vary widely, but the reasoning process used to reach the conclusion should be closely examined. It is important that both trust and distrust are based on facts, and not gut feelings, instincts, paranoid conceptions, unfounded hearsay or the words of others.

It is unsurprising that the Whonix ™ project and other anonymity platforms / tools claim to be honest, but written assurances are worthless. For an informed decision, it is worth looking at the bigger Whonix ™ picture: core components, affiliations, project track record, and how reasonable trust might be established.

Freedom Software and Public Scrutiny[edit]

Whonix ™ and other Freedom Software makes it possible to check the source code to determine how a software distribution functions and what it consists of. Suitably skilled individuals can thoroughly audit the code to search for the presence of any malicious code, like a backdoor. In addition, software can be manually built from source code and the result compared against any versions that are pre-built and already being distributed, like the Whonix ™ ova images that can be downloaded from whonix.org. This comparison can determine whether any malicious changes were made, or if the distributed version was actually built with the source code.

Naturally most people do not have the requisite knowledge, skills or time to properly audit software. However, the public scrutiny of popular, open source software implies a certain degree of trustworthiness. The axiom attributed to Linus Torvalds ^[1] -- "Given enough eyeballs, all bugs are shallow" -- is a reasonable assumption in user communities that are large, vibrant, and focused on fixing security vulnerabilities quickly. ^[2] The Freedom Software community has a strong tradition of publicly reporting and resolving serious issues, and a large pool of developers and beta testers can help to identify and remedy problems. ^[3]

The opposite of Freedom Software is non-freedom software. Freedom Software provides strong advangages over non-freedom software, which should be avoided. The case for Freedom Software is made on the avoid non-freedom software wiki page.

Table: Finding Backdoors in Freedom Software vs Non-Freedom Software

	Non-Freedom Software (precompiled binaries)	Freedom Software (source-available)
Original source code is reviewable	No	Yes
Compiled binary file can be decompiled into disassembly	Yes	Yes
Regular pre-compiled binaries	Depends [4]	Yes
Obfuscation [archive] (anti-disassembly, anti-debugging, anti-VM) [5] is usually not used	Depends [6]	Yes [7]
Price for security audit searching for backdoors	Very high [8]	Lower
Difference between precompiled version and self-compiled version	Unavailable [9]	Small or none [10]
Reverse-engineering [archive] is not required	No	Yes
Assembler language skills required	Much more	Less
Always legal to decompile / reverse-engineer	No [11] [12]	Yes [13]
Possibility of catching backdoors via observing incoming/outgoing Internet connections	Very difficult [14]	Very difficult [14]
Convenience of spotting backdoors	Lowest convenience [15]	Very high convenience [16]
Difficulty of spotting "direct" backdoors [17] [18] [19]	Much higher difficulty [20]	Much lower difficulty [21]
Difficulty of spotting a "bugdoor" [22]	Much higher difficulty [23]	Lower difficulty
Third parties can legally release a software fork [archive], a patched version without the backdoor	No [24]	Yes [25]
Third parties can potentially make (possibly illegal) modifications like disabling serial key checks [26]	Yes	Yes
Software is always modifiable	No [27]	Yes
Third parties can use static code analysis tools	No	Yes
Third parties can judge source code quality	No	Yes
Third parties can find logic bugs in the source code	No	Yes
Third parties can find logic bugs in the disassembly	Yes	Yes
Benefits from population-scale scrutiny	No	Yes
Third parties can benefit from debug symbols [archive] during analysis	Depends [28]	Yes
Display source code intermixed with disassembly	No	Yes [29]
Effort to audit subsequent releases	Almost same [30]	Usually lower [31]
Forum discussion: Finding Backdoors in Freedom Software vs Non-Freedom Software [archive]

Spotting backdoors is already very difficult in Freedom Software where the full source code is available to the general public. Spotting backdoors in non-freedom software composed of obfuscated binaries is exponentially more difficult. ^{[32] [33] [34] [35] [36] [37] [38] [39]}

To further improve the situation in the future, the Freedom Software community is working on the Reproducible Builds ^[archive] project. Quote:

Reproducible builds are a set of software development practices that create an independently-verifiable path from source to binary code.

Whilst anyone may inspect the source code of free and open source software for malicious flaws, most software is distributed pre-compiled with no method to confirm whether they correspond.

This incentivises attacks on developers who release software, not only via traditional exploitation, but also in the forms of political influence, blackmail or even threats of violence.

This is particularly a concern for developers collaborating on privacy or security software: attacking these typically result in compromising particularly politically-sensitive targets such as dissidents, journalists and whistleblowers, as well as anyone wishing to communicate securely under a repressive regime.

Whilst individual developers are a natural target, it additionally encourages attacks on build infrastructure as an successful attack would provide access to a large number of downstream computer systems. By modifying the generated binaries here instead of modifying the upstream source code, illicit changes are essentially invisible to its original authors and users alike.

The motivation behind the Reproducible Builds project is therefore to allow verification that no vulnerabilities or backdoors have been introduced during this compilation process. By promising identical results are always generated from a given source, this allows multiple third parties to come to a consensus on a “correct” result, highlighting any deviations as suspect and worthy of scrutiny.

This ability to notice if a developer has been compromised then deters such threats or attacks occurring in the first place as any compromise would be quickly detected. This offers comfort to front-liners that they not only can be threatened, but they would not be coerced into exploiting or exposing their colleagues or end-users.

Several free software projects ^[archive] already, or will soon, provide reproducible builds.

Trusting Debian GNU/Linux[edit]

Nearly all the software shipped in Whonix ™ comes from the Debian GNU/Linux distribution ^[archive]. Debian's packages are heavily scrutinized as it is one of the largest Linux distributions ^[archive] at present. Debian is also one of the most popular distributions for derivative platforms; Ubuntu Linux ^[archive] is a Debian derivative, and the same applies to all Ubuntu derivatives such as Linux Mint ^[archive].

The sheer number using Debian's software packages and the large developer pool inspecting software integrity are significant factors in Debian's favor. Debian regularly identifies and patches serious security issues ^[archive] like the infamous SSH PRNG vulnerability ^[40], but backdoors or other purposeful security holes have never been discovered to date. Debian's focus on security is further evidenced by their Security Audit team which constantly searches for new or unfixed security issues. ^[41]

Trusting Tor[edit]

Whonix ™ anonymity is based on Tor, which is developed by The Tor Project ^[archive]. Tor is a mature anonymity network with a substantial user base, and it has developed a solid reputation after around two decades of development. Tor's distributed trust model makes it difficult for any single entity to capture a user's traffic and identify them on a consistent basis.

Tor and its general development are subject to heavy public scrutiny by academics, security professionals and a host of developers. ^[42] For example, there is a body of Tor research related to potential attack vectors on onion routing and the adequacy of current defenses, and the source code has undergone several external audits. Like any software project, numerous security issues have been identified and resolved over the years, but a purposeful backdoor has never been discovered. ^[43] Theories about deliberate backdoors in Tor are considered highly speculative and lacking any credible basis.

Trusting Whonix ™[edit]

In one sense, Whonix ™ is the simple union of Debian and Tor and a mechanism to glue them together. If a user already trusts Debian and The Tor Project, then a method for assessing Whonix ™ trustworthiness is also necessary.

The Whonix ™ project was founded on 11 January, 2012. It previously existed under different project names, including TorBOX and aos. As mentioned earlier, Whonix ™ is Freedom Software which makes the source code available for inspection. In the main, Whonix ™ is comprised of specifications for which Debian software packages should be installed and their appropriate configuration. See also this list of notable reviews and feedback about the security of Whonix ™.

With a relatively small development team and estimated user base, the "many eyeballs" theory may work against Whonix ™ at present. However, the source code is comparably small and devoid of complexities, meaning the project is in relatively good shape compared to many other similar projects. Interested readers can learn more about the Whonix ™ specification and design here. ^[44]

With these factors in mind, the reader can now make an informed decision about the trustworthiness of Whonix ™.

Whonix ™ Warrant Canary[edit]

The Whonix ™ warrant canary ^[archive] is intended to provide a means of communication to users in the event Whonix ™ is served with a secret subpoena, despite legal prohibitions on revealing its existence. For any canary in force, once the signature of the canary file is verified with OpenPGP, this confirms that no warrants have been served on the Whonix ™ project.

Note: the canary date of issue is represented by the gpg signature date. A new canary should be released within 4 weeks. ^[46]

The canary and signature are available here:

• Canary text file: https://download.whonix.org/whonixdevelopermetafiles/canary/canary.txt ^[archive] (v3 onion ^[archive])
• OpenPGP signature: https://download.whonix.org/whonixdevelopermetafiles/canary/canary.txt.asc ^[archive] (v3 onion ^[archive])

As a backup, the canary and signature are also available on gitlab and github: ^[47]

• https://gitlab.com/Whonix/canary ^[archive]
• https://github.com/adrelanos/canary ^[archive]

Readers are reminded this canary scheme is not infallible. The canary declaration is provided without any guarantee or warranty, and it is not legally binding upon any parties in any form. The signer should never be held legally responsible for any statements made in the canary.

Related:

• Forum Discussion ^[archive]
• Dev/Warrant Canary Draft

Trusting Downloaded Images[edit]

Users should not blindly trust the Whonix ™ project or its developers. Logically it is unwise to trust unknown persons, especially on the Internet. On that basis, trust in Whonix ™ developers should not rely on his public persona or the appearance of the Whonix ™ project alone. Whonix ™ may be or could become a high profile target, and it is risky to assume that developer's build machines would remain clean under those circumstances.

Trusting the Download Location[edit]

Binary images can be trusted to some extent if a user verifies that they received exactly the same code as thousands of other users, and no one has found or publicly reported any serious security issues. This requires verification of the Whonix-Workstation ™ and Whonix-Gateway ™ images using the available OpenPGP signatures. ^[48] All source code tags for releases are OpenPGP-signed by lead Whonix ™ developer Patrick Schleizer.

In order of increasing security, the Whonix ™ images can be:

1. Downloaded via https://www.whonix.org ^[archive]. TLS provides some trust and integrity of the hash file, but it is still advisable to check the site's certificate and perform digital software signature verification (instructions).
2. Downloaded over the Whonix ™ v3 onion address ^[archive] with Tor Browser before digital software signature verification. Onion addresses provide a higher standard of authentication than clearnet addresses.
3. Built from source since it is a relatively easy procedure. ^[49]

Trusting Whonix ™ Images[edit]

Table: Maintainer Overview - Platform, Source Code, Binary Images, Permissions

	Whonix ™ VirtualBox	Whonix ™ KVM	Qubes-Whonix ™	Built from Source Code
Source Code Creation	Patrick	Patrick	Qubes project and Patrick	Patrick
Source Code Trust	Patrick	Patrick	Qubes project and Patrick	Patrick
Binary Image Creation	Patrick	HulaHoop	Qubes project [50]	-
Binary Images Trust	Patrick	HulaHoop	Qubes project and Patrick	-
Package Upgrades Creation	Patrick	Patrick	Qubes project and Patrick	-

Since Whonix ™ is based on Debian, Debian releases package upgrades. See also: Trusting Debian GNU/Linux.

Trusting Tor Browser[edit]

Tor Browser:

• Developed by The Tor Project (TPO).
• Pre-installed inside Whonix-Workstation ™. ^[51]
• On the Whonix ™ Intel / amd64 architecture:
  • Tor Browser Internal Updater downloads Tor Browser which is built by TPO from the TPO website.
  • Tor Browser Downloader by Whonix ™ downloads from the TPO website.
• On the Whonix ™ arm64 architecture:
  • Links / status on arm64 architecture support generally: Dev/Porting
  • Tor Browser Internal Updater is unavailable?
  • Tor Browser Downloader by Whonix ™ downloads an unofficial build, community port from Heikki Lindholm ^[archive] (OpenPGP (gpg) public key ^[archive]) on sourceforge, see: Tor Browser Ports ^[archive].
  • Forum discussion: ARM64 Tor Browser Maintainer ^[archive]

Whonix ™ Binary Images Policy[edit]

Only the currently existing Whonix ™ binary image maintainers are permitted to redistribute software forked binary builds Whonix ™. Reasons:

• Verifiable Builds, let alone reproducible builds, let alone automatic verification of reproducible builds, rebuilders ^[52] are unavailable and their availability many years ahead. In other words, the binary builds by Whonix ™ are not yet verifiably created from project's own source code (no hidden source code ^[53] in the project's own source code).
• Binary images unfortunately still require trust.
• Others are welcome to exercise their right to software fork ^[archive] the Whonix ™ project under the respective licenses. (Why Whonix ™ is Freedom Software)
• There is no restriction of software redistribution rights under the respective licenses. (Whonix:Copyrights)
• Whonix ™ is a trademark, see Whonix ™ Trademark Policy.
• To protect the reputation of the Whonix ™ project, quality control, non-maliciousness, potential Evil Developer Attack.
• Whonix ™ is Software Fork Friendly.
• Trademark protection is commonplace even for Freedom Software. For example, see Tor Project, which also develops Freedom Software, The Tor Project Trademark Policy ^[archive] or Debian Trademark Policy ^[archive].

A reasonable process on how new Whonix ™ binary image maintainers could be securely admitted is yet to be developed. Please start a new Whonix ™ forum thread if you are interested to develop the process and/or to become a Whonix ™ binary image maintainer.

Please contribute towards Whonix ™ source code generally or specifically towards verifiable builds, reproducible builds and rebuilders^[52] so the trust requirement can be removed from the equation.

Builds from Source Code versus Builds including Binary Packages[edit]

What "building from source code" means in context of building Linux distributions from source code is not well defined. To explain the situation for Whonix ™ it is first important to mention the general, unspecific situation for other Linux distributions.

Rhetoric ^[54] exercises left for the reader:

1. Build a Debian installer ISO completely from source code without using any binary packages from packages.debian.org. Unfortunately, this is difficult. There was once a bounty Build Debian Packages from Source Code ^[archive] worth $ 3000 USD but no implementation was ever contributed. See also How to update all Debian packages from source code? ^[archive], DebianBootstrap ^[archive] and rebootstrap ^[archive]. ^[55]

   In this context bootstrapping refers to building binaries for an architecture from source without using any pre-built binaries for that architecture. In the past 20 years about 20 architectures have been bootstrapped for Debian. At all times this has been a manual and non-repeatable process. rebootstrap is trying to address the very early bootstrap phase involving the gcc/eglibc dance.

2. Install Debian using installer ISO (from completely source code) without using any binary packages from packages.debian.org.
3. Upgrading Debian completely from source code without using any binary packages from packages.debian.org.
4. Using any Debian (from source code or not): Build and install from source code while also acquiring all the build dependencies without using any binary packages from packages.debian.org. apt-build ^[archive] is the closest approximation of that but it uses binary packages from packages.debian.org to fulfill build dependencies. The development of apt-build stalled and the package was orphaned ^[archive].
5. Build any Qubes template image or a Qubes installer ISO from source code without using any binaries from deb.qubes-os.org. This will probably be very difficult or impossible without Qubes source code modifications. Qubes build script function installQubesRepo ^[archive] enables deb.qubes-os.org, i.e. binary packages from deb.qubes-os.org are used during Qubes build process.
6. Attempt the previous example but without using packages.debian.org and its Fedora equivalent.
7. Attempt to upgrade an installed Qubes installation using Qubes source code only without using any binary packages from qubes-os.org.
8. Create your own packages.debian.org, deb.whonix.org and/or deb.qubes-os.org under a different domain name or on local disk.

All of the above tasks are very difficult tasks for which unfortunately very little documentation exists. Even description and awareness of the issues rarely exists. These issues are however unspecific to Whonix ™. These are mentioned to explain the context and set realistic expectations of what the Whonix ™ project might be able to provide. The situation in Whonix ™ is as follows:

• Non-Qubes-Whonix ™:
  • Builds: When Whonix ™ is built from source, no contents from whonix.org are used and no binaries created by the Whonix ™ project are used. However, unfortunately running Whonix ™ build script results in using binary packages from packages.debian.org. This is because Whonix ™ inherits the same limitations as the above examples mentioning Debian.
  • APT repository: No issues with Whonix ™ APT Repository Default Settings.
  • Upgrades from source code: There is wiki page Upgrading Whonix ™ Deb Packages from Source Code and a locally-upgrade-whonix-debian-packages ^[archive] but, see footnote. ^[56]
• Qubes-Whonix ™: Inherits the same limitations as the above examples mentioning Qubes. Unfortunately, binary packages from packages.debian.org, deb.whonix.org and deb.qubes-os.org are used.

Undeniably this situation is unsatisfactory. In the future, Verifiable Builds or even fully reproducible builds ^[archive], and rebuilders ^[archive] will hopefully reduce or eliminate the requirement to trust binaries.

Asking about these issues will very most likely not result in people writing documentation how to accomplish these very difficult tasks. The only realistic option to improve this situation is to contribute to reproducible builds and/or build from source code related projects.

Related:

• Trusting Downloaded Images
• Whonix ™ Updates
• Software Update APT Repository Security
• Software Build Process Security
• Verifiable Builds
• Malware
• Malware Audits

Trusting the Whonix ™ Website[edit]

Web Application Shortcomings[edit]

As noted in the Privacy on the Whonix ™ Website chapter, three separate web-based platforms are currently in use:

1. Discourse ^[archive] for the Whonix ™ forums.
2. MediaWiki ^[archive] for online documentation.
3. Phabricator ^[archive] (mostly) for the Whonix ™ project's issue/bug tracker.

The problem is these web applications (web apps) are developed independently from Whonix ™. This means Whonix ™ developers have little to no control over the course these projects take. Since privacy and security issues often take a back seat to "enhanced features", websites relying on these or similar web apps can at best only provide privacy by policy, which is equivalent to a promise.

It is infeasible from a monetary, time and manpower perspective to address perceived shortcomings in these web apps. This means the Whonix ™ community should not place undue trust in the live version of this site on the Internet, due to the potential for interference.

Distrusting Infrastructure[edit]

In an identical fashion to the Qubes project, Whonix ™ has adopted the principle that all infrastructure should be explicitly distrusted. Infrastructure in this context refers to "...hosting providers, CDNs, DNS services, package repositories, email servers, PGP keyservers, etc."

Third parties who operate infrastructure are "known unknowns" and potentially hostile. It is safer to voluntarily place trust in a few select entities, such as the contributors of Whonix ™ packages, the holder(s) of Whonix ™ signing keys and so on. By sufficiently securing endpoints, it is unnecessary to try and improve the trustworthiness of those operating the "mid-points". This also provides two benefits: Whonix ™ forgoes the need to invest valuable resources on the problem, and no illusory security expectations are raised in the Whonix ™ community.

Quote ^[archive] Qubes OS ^[archive] (security-focused operating system):

What does it mean to “distrust the infrastructure”?

A core tenet of the Qubes philosophy is “distrust the infrastructure,” where “the infrastructure” refers to things like hosting providers, CDNs, DNS services, package repositories, email servers, PGP keyservers, etc. As a project, we focus on securing endpoints instead of attempting to secure “the middle” (i.e., the infrastructure), since one of our primary goals is to free users from being forced to entrust their security to unknown third parties. Instead, our aim is for users to be required to trust as few entities as possible (ideally, only themselves and any known persons whom they voluntarily decide to trust).

Users can never fully control all the infrastructure they rely upon, and they can never fully trust all the entities who do control it. Therefore, we believe the best solution is not to attempt to make the infrastructure trustworthy, but instead to concentrate on solutions that obviate the need to do so. We believe that many attempts to make the infrastructure appear trustworthy actually provide only the illusion of security and are ultimately a disservice to real users. Since we don’t want to encourage or endorse this, we make our distrust of the infrastructure explicit.

Also see: Should I trust this website? ^[archive]

Self-Hosting vs Third Party Hosting[edit]

Some users mistakenly believe that servers of security-focused projects are virtually impenetrable and hosted in the homes of developers; this is not the case. The whonix.org server is actually hosted at an Internet hosting company. Similarly, The Tor Project ^[archive] and Tails ^[archive] servers are not hosted in a developer's home either. Hosting at home is the exception, rather than the rule. At the time of writing, there are no known cases where servers are hosted in a developer's home. This means employees of the associated Internet hosting company have physical access rights to the server, along with any other capable, malicious actors.

Since virtually every project is hosted by a third party (an Internet hosting company), the capability to physically secure server hardware is largely forfeited. Without physical security and due to the risk of untrusted visitors, a hardware backdoor could easily compromise the security of the server.

Any demand that servers ought to be super secure and hosted in a developer's home is idealistic. Home Internet connections are generally too slow to meet the requirements of a public web server in terms of traffic quota and connection upload speed. Internet service providers (ISPs) do not usually allow a busy public web server to be hosted on home connections; throttled connections or terminated contracts are likely if that happens.

The "proper solution" would require purchase of a business Internet uplink, similar to becoming an Internet hosting company. This would incorporate a business building with a good Internet uplink, full camera security, security officers and so forth. Unfortunately this is economically infeasible at the current stage of project development.

Security Level[edit]

Many web applications in use by whonix.org did not provide software signatures at the time of installation or still do not provide them. Therefore, in stark contrast to software installed by default in Whonix ™, for the whonix.org server it was not possible to always enforce verification of software signatures.

Many web application and extensions updaters did not, or still do not, securely verify software signatures. Therefore, the security level of most servers is probably only equivalent to plaintext. In the case of the whonix.org server, the system security level is only equivalent to always use TLS and not always use software signatures verification.

Server Privacy[edit]

In the past, various suggestions for "perfect server privacy" ^[57] were made such as "self-hosting in developers' homes" or "host the server outside the five eyes ^[archive] (nine eyes, fourteen eyes ^[archive]) countries". Despite the good intentions, these suggestions do not easily translate into an actionable plan.

First, these suggestions assume there is a sane method of rating the privacy protections afforded by a specific country. Moreover, the privacy rights granted for local citizens in a specific jurisdiction do not necessarily extend to non-citizens. Whonix ™ developers are unaware of any project that rates privacy protections in this way, considers the feasibility of operating servers (by running tests), and then makes recommendations for locations which provide the best possible privacy.

In today's world following the Snowden disclosures, it has to be assumed that if surveillance is possible it is being done. The likelihood is that surveillance is undertaken in all jurisdictions, and it is only a matter of degree.

Even The Tor Project -- a much older, established and better funded organization -- does not attempt to implement any suggestion concerning "perfect server privacy". As noted on their sponsor's page ^[archive]:

Fastly generously hosts our Tor Browser update downloads that can be fetched anonymously.

Fastly ^[archive] is providing content delivery network (CDN) services and is headquartered in America (arguably the most aggressive member of the five eyes network). Even Debian uses CDNs Amazon AWS and Fastly ^[archive].

In a similar fashion to the Distrusting Infrastructure chapter, Whonix ™ has concluded it is not worthwhile investing valuable resources to try and provide "perfect server privacy", because it is simply uneconomical. For this reason, the viewpoint that no undue trust should be placed in the server arrangements is made explicit.

Server Security[edit]

Server security issues should not be conflated with software security issues. If an advanced adversary wanted to tarnish the reputation of any security-focused project, then breaking into the data center where it was hosted and "hacking" them would be one way to achieve that aim. Projects that are honest need to mention this possibility beforehand, so it is not unexpected.

The world's largest and most profitable technology companies like Google, Facebook, Microsoft and Amazon can easily afford to employ large, dedicated and skilled teams of system administrators to work around the clock to protect their servers. ^[58] For small projects, this scale of server protection is completely unrealistic.

Software Update APT Repository Security[edit]

A compromise of the whonix.org server would not result in a compromise of users attempting to upgrade Whonix ™. This is because of a standard APT security feature: digital signature verification of APT repository metadata (SecureApt ^[archive]). An adversary who compromised the whonix.org server would lack the signing key required to generate valid signed APT repository metadata. Invalid APT repository metadata would be rejected by the user's APT updater software. APT repository metadata is signed locally on the developer's computer before the signed metadata is uploaded to the whonix.org server. The Whonix ™ APT repository signing key is never exposed to the server. Thanks to digital signature verification the Whonix ™ software update APT repository can be in theory considered more secure than than the whonix.org website.

Software Build Process Security[edit]

A compromise of the whonix.org server would not result in a compromise of software packages (image downloads, Debian packages, .debs) because all software is built locally on the developer's computer. No binary builds offered to download for users of software developed under the Whonix ™ umbrella is ever created on remote servers hosted by third parties. Users who always correctly verify software signatures could detect malicious software before use. However, note these Consequences of Server Compromise.

Server Privacy vs Server Security[edit]

In an ideal world, both server privacy and server security would be maximized at the same time. However, in the real world this is an impossibility.

In a world with specialization and division of labour, those companies who excel at hosting web applications have more focus, time, energy, knowledge and money to work on server security; it is their raison d'etre (reason for being). In contrast, small projects use web applications only as a means to an end. Therefore, using third party web application hosters may provide better security than self-hosting, but better server privacy demands self-hosting. This means it is impossible to optimize both security and privacy simultaneously; the goals are at odds with each other.

Server Downtime[edit]

The almost perfect uptime of popular web services such as Google, Facebook, and Amazon (perhaps 99.99 per cent) might lead some to conclude this is an easy goal to achieve; this is a false assumption.

Expecting the same uptime from much smaller projects like Whonix ™ is unrealistic. At best, maybe only 99.0 per cent uptime can be provided because no resources are spent on server uptime statistics, server upgrades need to be performed, and reboots are necessary. These factors necessarily lead to downtime when the website is unavailable. With a huge budget it would be possible to approach the 99.99 per cent uptime that popular websites have via technical solutions such as server farms, load balancing, and failover ^[archive], but this is infeasible for small projects. Similarly, large companies can afford to pay for whole teams of system administrators who are working 24/7, in concert with these technical options. Again, small projects do not have that option.

Finally, server downtime is not evidence of a server compromise, but normally relates to server issues (for example, failing hard drives) and routine server maintenance.

Consequences of Server Compromise[edit]

A compromised whonix.org would result in one or more of the following issues:

• Provision of poor and/or malicious advice to visitors of the whonix.org website.
• Offer malicious software downloads to users who do not always verify software signatures.
• Unavailability of legitimate software downloads and updates.
• Reputational damage for Whonix ™.

Conclusion[edit]

Due to the multiple issues outlined in this section, the software produced by the Whonix ™ project is theoretically considered more secure than the website provided by the Whonix ™ project (whonix.org). The Whonix ™ software is the main product delivered by the Whonix ™ project, while the whonix.org server is only a tool to document and deliver Whonix ™. For further reading on this topic, see: Website and Server Tests.

OpenPGP[edit]

Introduction[edit]

Fingerprint Trust[edit]

Most users retrieve OpenPGP fingerprints directly from a website and then download an associated key from a key server. The problem with this method is that TLS is fallible and the connection could be insecure or broken. Greater security necessitates a key signing party, whereby a direct and trusted path of communication can be confirmed by all attendees. If this step is not followed, OpenPGP is only secure as TLS.

It is often impossible to meet this condition of meeting in person. To mitigate the risk, any OpenPGP fingerprint should be cross-referenced on multiple "secure" (https://) sites. An additional fail-safe is to use an alternative authentication system, for example comparing the Tor signing keys on both the clearnet ^[archive] and .onion ^[archive] domains.

Onion services offer strong authentication via multiple layers of encryption ^[archive]. This does not prohibit an advanced adversary from trying to impersonate an onion service, but together with multiple fingerprint sources, it becomes increasingly difficult and improbable that a single entity could impersonate them all.

Whonix ™ Binaries and Git Tags[edit]

All Whonix ™ binaries are OpenPGP-signed by Whonix ™ developer Patrick Schleizer. ^[59] The source code is directly available on github over TLS, and it can be cloned using git over https://. Git tags for each release are also OpenPGP-signed by Whonix ™ developer Patrick Schleizer. Users can also request signed git development tags from the same developer.

Even if Whonix ™ developers are distrusted, verifying binary downloads or git tags with OpenPGP is still useful. For example in order to audit Whonix ™, it is important to verify the download came from Whonix ™ developers and that it was not tampered with by third parties. This is a realistic threat, as these recent examples show:

• An attacker could modify source codes on github ^[archive] (w ^[archive])
• sourceforge hacked ^[archive] (w ^[archive])
• sourceforge mirror hacked ^[archive] (w ^[archive])

The OpenPGP key also ensures that if the Whonix ™ infrastructure is ever compromised by a powerful adversary (such as a domain takeover), the original Whonix ™ developers can at least prove they owned the infrastructure.

Whonix ™ Developer OpenPGP Guidelines[edit]

All long-term Whonix ™ developers are encouraged to:

• Create a 4096/4096 RSA/RSA OpenPGP key.
• Retrieve the latest gpg.conf which comes with Whonix-Workstation ™ for stronger hashes, no-emit-version, and other improved settings.
• Store the private key inside an encrypted file.
• Make a backup of that encrypted file.
• Remember the password and regularly test one's memory of it.
• Upload the encrypted file to a (free) online cloud-based host to protect against theft, fire, natural events and so on.

From the beginning of the Whonix ™ project, greater trust has been placed in developers who publish their OpenPGP public key earlier on, since this reduces the probability of an evil developer attack.

Verifiable Builds[edit]

Verifiable .ova Releases[edit]

Whonix ™ previously had a feature which allows the community to check that Whonix ™ .ova ^[60] releases are verifiably created from the project's own source code - verifiable builds. ^[61] This only proves that the person and machine ^[62] building Whonix ™ have not added anything malicious, such as a backdoor. ^[63] It does not prove there are no backdoors present in Debian. This is not possible, because neither Debian ^[64] nor any other operating system provides deterministic builds yet. ^[65]

This feature does not attempt to prove there are not any vulnerabilities present ^[66] in Whonix ™ or Debian. Fatal outcomes are still possible via a remotely exploitable ^[67] bug in Whonix ™ or Debian, a flaw in Whonix's firewall which leaks traffic, or code phoning home ^[68] the contents of the HDD/SSD. Community effort is a precondition to improved security with this feature, particularly auditing of Whonix ™ and Debian source code to check for possible backdoors and vulnerabilities.

In summary, this feature is useful and potentially improves security, but it is not a magical solution for all computer security and trust issues. The following table helps to explain what this feature can achieve.

Table: Verifiable Builds Comparison

	Whonix ™	Tails	Tor Browser	Qubes OS TorVM	corridor
Deterministic builds [69]	No	No (planned) [70]	Yes [71]	No	Not applicable [72]
Based on a deterministically built [69] operating system	No [73]	No [73]	Not applicable	No [73]	No [73]
Verifiably no backdoor in the project's own source code	Invalid [74]	Invalid [74]	Invalid [74]	Invalid [74]	Invalid [74]
Verifiably vulnerability-free [archive]	No [75]	No [75]	No [75]	No [75]	No [75]
Verifiably no hidden source code [53] in upstream distribution / binaries [76]	No [77]	No [77]	No [77]	No [77]	No [77]
Project's binary builds are verifiably created from project's own source code (no hidden source code [53] in the project's own source code)	No (deprecated) [78]	No	Yes	No	Not applicable [72]

Some readers might be curious why Whonix ™ was previously verifiable, while Debian and other distributions are not. In short, this is because Whonix is uncomplicated by comparison. In simple terms, Whonix ™ is a collection of configuration files and scripts, and the source code does not contain any compiled code and so on. In contrast, Debian is a full operating system, without which Whonix ™ would not exist. ^[79]

This feature was first made available in Whonix ™ 8. Only users who download a new image can profit from this feature. ^[80] It is not possible to audit versions older than Whonix ™ 8 with this script. ^[81]

This is only an an introduction to this topic; see Verifiable Builds for full details.

Verifiable Whonix ™ Debian Packages[edit]

This has been deprecated because it is difficult to implement before the experimental, Debian reproducible toolchain is merged into the stable release. ^[82] For full details on this topic, see Verifiable Whonix ™ Debian Packages.

Whonix ™ Updates[edit]

Introduction[edit]

An optional updater has been available in Whonix ™ since version 6 of the platform. ^[83] When it comes to trust, there is a large difference between building Whonix ™ from source code and using the Default-Download-Version.

APT Repository and Binary Builds Trust[edit]

When Whonix ™ is built from source code using the build script and the source code is audited by the builder to be non-malicious and reasonably bug-free, Whonix ™ developers are unable to access the system. On the other hand, if Whonix ™ APT repository is enabled, developers holding a Whonix ™ repository signing key could release a malicious update to gain full access to the machine(s). ^[84]

Even if the Whonix ™ APT repository is not used with the Default-Download version, it is still theoretically possible for Whonix ™ developers to sneak a backdoor into the binary builds which are available for download. ^[85] Although an unpleasant threat, using Whonix ™ APT repository poses a greater risk: a malicious Whonix ™ developer might sneak in a backdoor at any time.

It is easier to sneak backdoors into binary builds, since they contain compiled code in binary packages which are downloaded from the Debian repository when built.

APT Repository Default Settings[edit]

Non-Qubes-Whonix ™:

• Building from source code: Whonix ™ APT Repository is disabled by default. ^[86]
• Default binary download: Whonix ™ APT Repository is enabled by default.

Qubes-Whonix ™:

• Qubes/Install: Whonix ™ APT Repository is enabled by default.
• Building from source code: Whonix ™ APT Repository is enabled by default. ^[87]

Most users will have the Whonix ™ APT repository enabled. This means when updated Whonix ™ debian packages are uploaded to the Whonix ™ APT repository, these packages will be automatically installed when the system is upgraded. ^[88] If this behavior is unwanted, this can be disabled. Refer to the previous section outlining security implications before proceeding.

Security Conclusion[edit]

Legend:

• *: poor security.
• ****: best security.

Table: Build and APT Repository Security Comparison

	Binary Download with Whonix ™ APT Repository	Binary Download without Whonix ™ APT Repository	Built from Source Code and Whonix ™ APT Repository Enabled	Built from Source Code and Whonix ™ APT Repository Disabled
Security	*	**	*	****
Convenience	****	*	**	*

In summary:

• The Whonix ™ binary download using the Whonix ™ APT repository is the most convenient method, but also the least secure.
• It is somewhat safer to use the Whonix ™ binary download and then disable the Whonix ™ APT repository. However, the user must then manually download updated Whonix ™ deb packages upon release, and independently verify and install them.
• The greatest security comes from building Whonix ™ and updated packages from source code, particularly if the source code is verified before building Whonix ™.

Appendix[edit]

What Digital Signatures Prove[edit]

See Verifying Software Signatures for details on what digital signatures prove.

In short, a user must be careful to ensure the public keys that are used for signature verification are the Whonix ™ key pair belonging to the Whonix ™ developer of the component specific component. At time of writing there are two different components and signing keys.

• Whonix ™ Main, VirtualBox, APT Repository and Source Code Signing Key
• Whonix ™ KVM Signing Key

TLS[edit]

TLS, SSL and HTTPS are all flawed since they rely on the vulnerable Certificate Authority (CA) model; see here for further details and SSL/TLS alternatives. ^[89]

Evil Developer Attack[edit]

Introduction[edit]

An "evil developer attack" is a narrow example of an insider threat: ^[90]

Software development teams face a critical threat to the security of their systems: insiders.

[...]

An insider threat is a current or former employee, business partner, or contractor who has access to an organization’s data, network, source code, or other sensitive information who may intentionally misuse this information and negatively affect the availability, integrity, or confidentiality of the organization’s information system.

In the case of software, a disguised attack is conducted on the integrity of the software platform. While this threat is only theoretical, it would be naive to assume that no major software project has ever had a malicious insider. Whonix ™ and all other open source software projects face this problem, particularly those that are focused on anonymity such as VeraCrypt, ^[91] Tails, I2P, The Tor Project and so on.

Attack Methodology[edit]

A blueprint for a successful insider attack is as follows:

1. Either start a new software project or join an existing software project.
2. Gain trust by working hard, behaving well, and publishing your sources.
3. Build binaries directly from your sources and offer them for download.
4. Attract a lot of users by making a great product.
5. Continue to develop the product.
6. Make a second branch of your sources and add malware.
7. Continue to publish your clean sources, but offer your malicious binaries for download.
8. If undetected, a lot of users are now infected with malware.

An evil developer attack is very difficult for end users to notice. If the backdoor is rarely used, then it may remain a secret for a long time. If it was used for something obvious, such as adding all the users to a botnet, then it would be quickly discovered and reported on.

Open source software has some advantages over proprietary code, but certainly not for this threat model. For instance, no one is checking if the binaries are made from the proclaimed source and publishing the results, a procedure called "deterministic builds".^{[92] [93]} This standard is quite difficult to achieve, but is being worked towards. ^[94]

Related Attacks[edit]

While most security experts are focused on the possibility of a software backdoor, other insider attacks can have equally deleterious effects. For instance, the same methodology can be used to infiltrate a targeted project team but in a role unrelated to software development; for example, as a moderator, site administrator, wiki approver and so on. This approach is particularly effective in smaller projects that are starved of human resources.

Following infiltration, disruption is caused within the project to affect productivity, demoralize other team members and (hopefully) cause primary contributors to cease their involvement. For example, using a similar blueprint to that of the evil developer attack, a feasible scenario is outlined below:

1. Join an existing software project as a general member.
2. Gain trust by working hard, behaving well, assisting readily in forums, making significant wiki contributions and so on.
3. Attract a lot of community admiration by outwardly appearing to be a bona fide and devoted project member.
4. Eventually attain moderator, administrator or other access once team membership is extended. ^[95]
5. Continue to behave, moderate and publish well.
6. Once trust is firmly established, subtly undermine the authority, character and contributions of other team members. ^[96]
7. If the insider threat is undetected for a significant period, this can lead to a diminished software product due to a fall in contributions in numerous domains and team ill will.

Conclusion[edit]

The insider threat nicely captures how difficult it is to trust developers or other project members, even if they are not anonymous. Further, even if they are known and have earned significant trust as a legitimate developer, this does not discount the possibility of serious mistakes that may jeopardize the user. The motives and internal security of everyone contributing to major software projects like Tor, distribution developers and contributors, and the hundreds of upstream developers and contributors is a legitimate concern. ^[97]

The trusted computing base of a modern operating system is enormous. There are so many people involved in software and complex hardware development, that it would be unsurprising if none of the bugs in existence were intentional. While detecting software changes in aggregate may be easy (by diffing the hash sums), finding and proving that a change is a purposeful backdoor rather than a bug in well designed source code is near impossible.

Legal Issues[edit]

Users occasionally raise the possible privacy and security implications if contemporary, draft laws were to be passed. For example, how the Whonix ™ project would react to laws:

• banning end-to-end encryption
• outlawing anonymity tools like Tor
• demanding that operating systems include a backdoor

It is important to note that government members have diverse and conflicting interests. Bills which are hostile to Internet privacy and security are regularly introduced in various jurisdictions, but common sense usually prevails and ill-conceived legislation normally stalls and fails to become law. Conversely, bills that allocate funding to support cryptographic development and privacy tools garner support and are normally passed because most legislators understand their importance in an open society. While Internet privacy advocacy groups should remain vigilant, it is unproductive to become unduly stressed whenever a bill hostile to privacy or security is proposed.

Although it may be counter-intuitive, in the event privacy-hostile laws are passed this is not a Whonix ™-specific issue, even though Whonix ™ would obviously be affected. For the most part, Whonix ™ is a compilation of existing software packages provided by third parties which allow re-use in a compilation due to permissive licensing (Freedom Software). In this context, noteworthy components which Whonix ™ relies on directly or indirectly are the base operating system (Debian at time of writing) and an anonymizer (Tor at time of writing). At first, such a law would very likely harm the security properties of these and other projects (see footnote). ^[98]

Legal Jurisdiction[edit]

In response to the possibility of privacy-hostile laws being implemented, it is usually suggested that the Whonix ™ legal entity should relocate to a different country. The effectiveness of moving to another jurisdiction would of course depend upon the specifics of the legal text, however it is unlikely that simple legal loopholes would exist. For example, legal entity relocation does or did not help people who would like to sell controlled substances (such as medicine) or goods (such as weapons) without all authorizations required by law. Another example are financial services; this is also why unnamed stock certificates on the blockchain do not exist.

Some U.S. laws apparently apply to all international jurisdictions. Take the case of Kim Dotcom who is a German/Finnish dual national. Although a permanent resident of and physically present in New Zealand at the time of alleged copyright infringement charges brought forth by the USA, he had his assets seized, worldwide bank accounts frozen, was arrested, and is fighting extradition to the USA. As Kim Dotcom summarized on Twitter ^[archive]:

I never lived there
I never traveled there
I had no company there

But all I worked for now belongs to the U.S.

How The US Government Legally Stole Millions From Kim Dotcom ^[archive]

Legal Compliance[edit]

Sometimes it is suggested to simply not comply with new laws impacting privacy, however this is an unreasonable request. Most laws include an enforcement mechanism, although it can be selectively applied depending on government interests. Serious penalties apply if a law is not being complied with, especially for repeat and continuous offenses. Penalties may include:

• imprisonment
• monetary fines
• for failure to pay monetary fines, the threat of asset seizure, imprisonment or worse

Law enforcement has incredibly long arms. In most cases there is no way to openly defy the law for an extended period and get away with it. To a large degree policy issues cannot be fixed only via technological means; it must be combined with peaceful resistance on a political level. Government policy is affected by popular opinion, and those who support privacy-enhancing technologies can help the cause by sharing their reasoned opinions with others. Casual supporters are also important to raise public awareness.

Even if privacy-hostile laws are in place, it might still be permitted to contribute Open Source code to Open Source projects. For example, perhaps only the person(s) redistributing binary builds to the public would be held personally accountable. This is pure speculation until a new draft law catastrophic to security software eventuates.

If Whonix ™ was ever forced to add a backdoor by law, users would be notified and the project would be shut down before the law took effect. Fortunately, as yet there are no outrageous law proposals that would force the continued running of backdoored projects. In this case, efforts might focus on a new Linux-based project centered on stability, reliability, documentation, recovery, and usability.

Forum discussion:
EU Wants To Create Device/OS Level Backdoor ^[archive]

Other Projects Discussing Trust[edit]

• Tails is a live CD or USB that aims to preserve privacy and anonymity - Tails about trust. ^[archive] (w ^[archive])
• I2P (anonymizing network) has also discussed development attacks ^[archive]. (w ^[archive])
• Qubes OS: What digital signatures can and cannot prove ^[archive] (w ^[archive])
• Miron’s Weblog: Attack Scenarios on Software Distributions ^[archive] (w ^[archive])
• A list of incidents concerning compromised servers: On distributing binaries ^[archive] (w ^[archive])

Footnotes[edit]

License[edit]

Whonix ™ Trust wiki page Copyright (C) Amnesia <amnesia at boum dot org>
Whonix ™ Trust 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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