Q (cipher)
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| Q | |
| General | |
|---|---|
| Designers | Leslie McBride |
| First published | November 2000 |
| Derived from | AES, Serpent |
| Cipher detail | |
| Key sizes | 128, 192, or 256 bits |
| Block sizes | 128 bits |
| Structure | Substitution-permutation network |
| Rounds | 8 or 9 |
| Best public cryptanalysis | |
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A linear attack succeeds with 98.4% probability using 297 known plaintexts.[1]
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In cryptography, Q is a block cipher invented by Leslie McBride. It was submitted to the NESSIE project, but was not selected.
The algorithm uses a key size of 128, 192, or 256 bits. It operates on blocks of 128 bits using a substitution-permutation network structure. There are 8 rounds for a 128-bit key and 9 rounds for a longer key. Q uses S-boxes adapted from Rijndael (also known as AES) and Serpent. It combines the nonlinear operations from these ciphers, but leaves out all the linear transformations except the permutation.[2] Q also uses a constant derived from the golden ratio as a source of "nothing up my sleeve numbers".
Q is theoretically vulnerable to linear cryptanalysis; Keliher, Meijer, and Tavares have an attack that succeeds with 98.4% probability using 297 known plaintexts.[1]
[edit] References
- ^ a b L. Keliher, H. Meijer, and S. Tavares (September 12, 2001). "High probability linear hulls in Q" (PDF/PostScript). Proceedings of Second Open NESSIE Workshop. Retrieved on 2006-12-16.
- ^ Eli Biham, Vladimir Furman, Michal Misztal, Vincent Rijmen (February 11, 2001). "Differential Cryptanalysis of Q" (PDF/PostScript). 8th International Workshop on Fast Software Encryption (FSE 2001): pp.174–186, Yokohama: Springer-Verlag. Retrieved on 2006-12-26.
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