[Pycrypto-checkins] [ pycrypto-Patches-1618042 ] XCBC-PRF with different ciphers

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Patches item #1618042, was opened at 2006-12-18 13:48
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Frederic Roudaut (fredericroudaut)
Assigned to: Nobody/Anonymous (nobody)
Summary: XCBC-PRF with different ciphers

Initial Comment:
XCBCPRF.py implements the XCBC-PRF algorithm as described by RFC 4434. It tries to respect PEP 247 (API for Cryptographic Hash Functions) also.
RFC 4434 describes the algorithm named AES-XCBC-PRF-128. It involves the use of AES in CBC mode with a set of extensions (XCBC) to overcome this limitation. In fact is the same algorithm as RFC 3664 (XCBC-MAC) except that the restriction on keys length (ie exactly the cipher block size, 128 bits from AES-XCBC-MAC) is removed.

Nevertheless since the key length used is adapted to the cipher block size, all ciphers may be used with XCBC-PRF
ie we could have with any key length (digest length):
- TripleDES-XCBC-PRF (8)
- AES-XCBC-PRF (16)
- DES-XCBC-PRF (8)
- BLOWFISH-XCBC-PRF (8)
- CAST-XCBC-PRF (8)

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