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 publiccryptanalysis | |
Alinear attack succeeds with 98.4% probability using 297 known plaintexts.[1] |
Incryptography,Q is ablock cipher invented by Leslie McBride. It was submitted to theNESSIE 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 asubstitution–permutation network structure. There are 8 rounds for a 128-bit key and 9 rounds for a longer key. Q usesS-boxes adapted fromRijndael (also known as AES) andSerpent. 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 thegolden ratio as a source of "nothing up my sleeve numbers".
Q is vulnerable tolinear cryptanalysis; Keliher, Meijer, and Tavares have an attack that succeeds with 98.4% probability using 297known plaintexts.[1]
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