Version Information

Twofish-Serpent 
Two ciphers in a cascade [15, 16] operating in XTS mode (see the section 
Modes of Operation
). 
Each 128-bit block is first encrypted with Serpent (256-bit key) in XTS mode and then with Twofish 
(256-bit key) in XTS mode. Each of the cascaded ciphers uses its own key. All encryption keys are 
mutually independent (note that header keys are independent too, even though they are derived 
from a single password – see the section 
Header Key Derivation, Salt, and Iteration Count
). See 
above for information on the individual cascaded ciphers. 

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Hash Algorithms 
In the Volume Creation Wizard, in the password change dialog window, and in the Keyfile 
Generator dialog window, you can select a hash algorithm. A user-selected hash algorithm is used 
by the TrueCrypt Random Number Generator as a pseudorandom “mixing” function, and by the 
header key derivation function (HMAC based on a hash function, as specified in PKCS #5 v2.0) as 
a pseudorandom function. When creating a new volume, the Random Number Generator 
generates the master key, secondary key (XTS mode), and salt. For more information, please see 
the section 
Random Number Generator
 and section 
Header Key Derivation, Salt, and Iteration 
Count
. 
RIPEMD-160 
RIPEMD-160, published in 1996, is a hash algorithm designed by Hans Dobbertin, Antoon 
Bosselaers, and Bart Preneel in an open academic community. The size of the output of RIPEMD-
160 is 160 bits. RIPEMD-160 is a strengthened version of the RIPEMD hash algorithm that was 
developed in the framework of the European Union’s project RIPE (
RACE Integrity Primitives 
Evaluation
), 1988-1992. RIPEMD-160 was adopted by the International Organization for 
Standardization (ISO) and the IEC in the ISO/IEC 10118-3:2004 international standard [21]. 
SHA-512 
SHA-512 is a hash algorithm designed by the NSA and published by NIST in FIPS PUB 180-2 [14] 
in 2002 (the first draft was published in 2001). The size of the output of this algorithm is 512 bits. 
Whirlpool 
The Whirlpool hash algorithm was designed by Vincent Rijmen (co-designer of the AES encryption 
algorithm) and Paulo S. L. M. Barreto. The size of the output of this algorithm is 512 bits. The first 
version of Whirlpool, now called Whirlpool-0, was published in November 2000. The second 
version, now called Whirlpool-T, was selected for the NESSIE (
New European Schemes for 
Signatures, Integrity and Encryption
) portfolio of cryptographic primitives (a project organized by 
the European Union, similar to the AES competition). TrueCrypt uses the third (final) version of 
Whirlpool, which was adopted by the International Organization for Standardization (ISO) and the 
IEC in the ISO/IEC 10118-3:2004 international standard [21]. 

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