Free and open-source disk encryption utility
VeraCrypt is a free and open-source utility for on-the-fly encryption (OTFE). The software can create a virtual encrypted disk that works just like a regular disk but within a file. It can also encrypt a partition or (in Windows) the entire storage device with pre-boot authentication.
VeraCrypt is a fork of the discontinued TrueCrypt project. It was initially released on 22 June 2013. Many security improvements have been implemented and concerns within the TrueCrypt code audits have been addressed. VeraCrypt includes optimizations to the original cryptographic hash functions and ciphers, which boost performance on modern CPUs.
Encryption scheme.
VeraCrypt employs AES, Serpent, Twofish, Camellia, and Kuznyechik as ciphers. Version 1.19 stopped using the Magma cipher in response to a security audit. For additional security, ten different combinations of cascaded algorithms are available:
The cryptographic hash functions available for use in VeraCrypt are BLAKE2s-256, SHA-256, SHA-512, Streebog and Whirlpool. VeraCrypt used to have support for RIPEMD-160 but it has since been removed in version 1.26.
VeraCrypt's block cipher mode of operation is XTS. It generates the header key and the secondary header key (XTS mode) using PBKDF2 with a 512-bit salt. By default they go through 200,000 to 500,000 iterations, depending on the underlying hash function used and whether it is system or non-system encryption. The user can customize it to start as low as 2,048 and 16,000 respectively.
Security improvements.
VeraCrypt audit.
QuarksLab conducted an audit of version 1.18 on behalf of the Open Source Technology Improvement Fund (OSTIF), which took 32 man-days. The auditor published the results on 17 October 2016. On the same day, IDRIX released version 1.19, which resolved major vulnerabilities identified in the audit.
Fraunhofer Institute for Secure Information Technology (SIT) conducted another audit in 2020, following a request by Germany's Federal Office for Information Security (BSI), and published the results in October 2020.
Security precautions.
There are several kinds of attacks to which all software-based disk encryption is vulnerable. As with TrueCrypt, the VeraCrypt documentation instructs users to follow various security precautions to mitigate these attacks, several of which are detailed below.
Encryption keys stored in memory.
VeraCrypt stores its keys in RAM; on some personal computers DRAM will maintain its contents for several seconds after power is cut (or longer if the temperature is lowered). Even if there is some degradation in the memory contents, various algorithms may be able to recover the keys. This method, known as a cold boot attack (which would apply in particular to a notebook computer obtained while in power-on, suspended, or screen-locked mode), was successfully used to attack a file system protected by TrueCrypt versions 4.3a and 5.0a in 2008. With version 1.24, VeraCrypt added the option of encrypting the in-RAM keys and passwords on x64 editions of Windows, with a CPU overhead of less than 10%, and the option of erasing all encryption keys from memory when a new device is connected.
Tampered hardware.
VeraCrypt documentation states that VeraCrypt is unable to secure data on a computer if an attacker physically accessed it and VeraCrypt is then used on the compromised computer by the user again. This does not affect the common case of a stolen, lost, or confiscated computer. The attacker having physical access to a computer can, for example, install a hardware or a software keylogger, a bus-mastering device capturing memory or install any other malicious hardware or software, allowing the attacker to capture unencrypted data (including encryption keys and passwords) or to decrypt encrypted data using captured passwords or encryption keys. Therefore, physical security is a basic premise of a secure system.
Some kinds of malware are designed to log keystrokes, including typed passwords, that may then be sent to the attacker over the Internet or saved to an unencrypted local drive from which the attacker might be able to read it later, when they gain physical access to the computer.
Trusted Platform Module.
VeraCrypt does not take advantage of Trusted Platform Module (TPM). VeraCrypt FAQ repeats the negative opinion of the original TrueCrypt developers verbatim. The TrueCrypt developers were of the opinion that the exclusive purpose of the TPM is "to protect against attacks that require the attacker to have administrator privileges, or physical access to the computer". The attacker who has physical or administrative access to a computer can circumvent TPM, e.g., by installing a hardware keystroke logger, by resetting TPM, or by capturing memory contents and retrieving TPM-issued keys. The condemning text goes so far as to claim that TPM is entirely redundant.
It is true that after achieving either unrestricted physical access or administrative privileges, it is only a matter of time before other security measures in place are bypassed. However, stopping an attacker in possession of administrative privileges has never been one of the goals of TPM. (See for details.) TPM might, however, reduce the success rate of the cold boot attack described above. TPM is also known to be susceptible to SPI attacks.
Plausible deniability.
As with its predecessor TrueCrypt, VeraCrypt supports plausible deniability by allowing a single "hidden volume" to be created within another volume. The Windows versions of VeraCrypt can create and run a hidden encrypted operating system whose existence may be denied. The VeraCrypt documentation lists ways in which the hidden volume deniability features may be compromised (e.g., by third-party software which may leak information through temporary files or via thumbnails) and possible ways to avoid this.
Performance.
VeraCrypt supports parallelized encryption for multi-core systems. On Microsoft Windows, pipelined read and write operations (a form of asynchronous processing) to reduce the performance hit of encryption and decryption. On processors supporting the AES-NI instruction set, VeraCrypt supports hardware-accelerated AES to further improve performance. On 64-bit CPUs VeraCrypt uses optimized assembly implementation of Twofish, Serpent, and Camellia.
License and source model.
VeraCrypt was forked from the since-discontinued TrueCrypt project in 2013, and originally contained mostly TrueCrypt code released under the TrueCrypt License 3.0. In the years since, more and more of VeraCrypt's code has been rewritten and released under the permissive Apache License 2.0.
The TrueCrypt license is generally considered to be source-available but not free and open source. The Apache license is universally considered to be free and open source. The mixed VeraCrypt license is widely but not universally considered to be free and open source.
On 28 May 2014 TrueCrypt ceased development under unusual circumstances, and there exists no way to contact the former developers.
VeraCrypt is considered to be free and open source by:
VeraCrypt is considered to not be free and open source by:
Most of these are due to Veracrypt and Truecrypt not having supported or endorsed licenses. For example, the FSF does not tolerate licenses that impose obligations on the end user for the execution of the software and therefore go against The Free Software Definition. Debian considers all software that does not meet the guidelines of its DFSG to be non-free.
Legal cases.
In US v. Burns, the defendant had three hard drives, the first being a system partition which was later found to contain caches of deleted child pornography and manuals for how to use VeraCrypt, with the second being encrypted, and the third having miscellaneous music files. Even though the defendant admitted to having child pornography on his second hard drive, he refused to give the password to the authorities. Despite searching for clues of previously used passwords on the first drive, and inquiries to the FBI about any weaknesses to the VeraCrypt software that could be used to access the drive partition, and brute-forcing the partition with the alphanumeric character set as potential passwords, the partition could not be accessed. Due to the defendant confessing to having child pornography on the encrypted drive, the prosecution applied to force the defendant to give away the password under the foregone conclusion doctrine in the All Writs Act.
In a search of a Californian defendant's apartment for accessing child pornography, a VeraCrypt drive that was over 900 Gigabytes was found as an external hard drive. The FBI was called to assist local law enforcement, but the FBI claimed to not have found a weakness in the VeraCrypt software. The FBI also denied having a backdoor within the VeraCrypt software. It was later found that another suspect had educated the defendant into using encryption to hide his photos and videos of child pornography. Because the defendant had admitted to having child pornography on the drive as a backup anyways and chat logs relating to the other suspect educating the defendant on how to use VeraCrypt, the foregone conclusion doctrine was used again.
References.
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