VeraCrypt is a fork of the discontinued TrueCrypt project.[8] 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.[9] For additional security, ten different combinations of cascaded algorithms are available:[10]
VeraCrypt's block cipher mode of operation is XTS.[13] It generates the header key and the secondary header key (XTS mode) using PBKDF2 with a 512-bitsalt. 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.[14] The user can customize it to start as low as 2,048 and 16,000 respectively.[14]
The VeraCrypt development team considered the TrueCrypt storage format too vulnerable to a National Security Agency (NSA) attack, so it created a new format incompatible with that of TrueCrypt. VeraCrypt versions prior to 1.26.5 are capable of opening and converting volumes in the TrueCrypt format.[15][16] Since ver. 1.26.5 TrueCrypt compatibility is dropped.[17]
An independent security audit of TrueCrypt released 29 September 2015 found TrueCrypt includes two vulnerabilities in the Windows installation driver allowing an attacker arbitrary code execution and privilege escalation via DLL hijacking.[18] This was fixed in VeraCrypt in January 2016.[19]
While TrueCrypt uses 1,000 iterations of the PBKDF2-RIPEMD-160 algorithm for system partitions, VeraCrypt uses either 200,000 iterations (SHA-256, BLAKE2s-256, Streebog) or 500,000 iterations (SHA-512, Whirlpool) by default (which is customizable by user to be as low as 2,048 or 16,000 respectively).[14] For standard containers and other partitions, VeraCrypt uses 500,000 iterations by default regardless of the hashing algorithm chosen (which is customizable by user to be as low as 16,000).[14] While these default settings make VeraCrypt slower at opening encrypted partitions, it also makes password-guessing attacks slower.[20]
Additionally, since version 1.12, a new feature called "Personal Iterations Multiplier" (PIM) provides a parameter whose value is used to control the number of iterations used by the header key derivation function, thereby making brute-force attacks potentially even more difficult. VeraCrypt out of the box uses a reasonable PIM value to improve security,[21] but users can provide a higher value to enhance security. The primary downside of this feature is that it makes the process of opening encrypted archives even slower.[21][22][23][24]
A vulnerability in the bootloader was fixed on Windows and various optimizations were made as well. The developers added support for SHA-256 to the system boot encryption option and also fixed a ShellExecute security issue. Linux and macOS users benefit from support for hard drives with sector sizes larger than 512. Linux also received support for the NTFS formatting of volumes.
Unicode passwords are supported on all operating systems since version 1.17 (except for system encryption on Windows).[15]
VeraCrypt added the capability to boot system partitions using UEFI in version 1.18a.[15]
Option to enable/disable support for the TRIM command for both system and non-system drives was added in version 1.22.[15]
RAM encryption for keys and passwords on 64-bit systems was added in version 1.24.[15]
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.[15][25][26] On the same day, IDRIX released version 1.19, which resolved major vulnerabilities identified in the audit.[27]
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,[30][31] several of which are detailed below.
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.[32] With version 1.24, VeraCrypt added the option of encrypting the in-RAMkeys 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.[15]
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.[33] 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.[34]
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.[35]
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.[36] 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.[37]
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.[38][39] However, stopping an attacker in possession of administrative privileges has never been one of the goals of TPM. (See Trusted Platform Module § Uses for details.) TPM might, however, reduce the success rate of the cold boot attack described above.[40][41][42][43][44] TPM is also known to be susceptible to SPI attacks.[45]
Plausible deniability
As with its predecessor TrueCrypt, VeraCrypt supports plausible deniability[46] by allowing a single "hidden volume" to be created within another volume.[47] The Windows versions of VeraCrypt can create and run a hidden encrypted operating system whose existence may be denied.[48] 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.[30]
Performance
VeraCrypt supports parallelized[49]: 63 encryption for multi-core systems. On Microsoft Windows, pipelined read and write operations (a form of asynchronous processing)[49]: 63 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.[49]: 64 On 64-bit CPUs VeraCrypt uses optimized assembly implementation of Twofish, Serpent, and Camellia.[15]
License and source model
VeraCrypt was forked from the since-discontinued TrueCrypt project in 2013,[8] 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,[50][51][52] and there exists no way to contact the former developers.
VeraCrypt is considered to be free and open source by:
Some members of the Open Source Initiative, including the director,[63] expressed concern about an older version of the TrueCrypt license, but the OSI itself has not published a determination regarding either TrueCrypt or VeraCrypt.
The Free Software Foundation has determined the TrueCrypt license to be non-free.[64] The FSF has not published a determination regarding the VeraCrypt license.
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.[65] 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.[66]
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.[67]
