Jump to content

Q (cipher)

From Wikipedia, the free encyclopedia

This is the current revision of this page, as edited by VulcanSphere (talk | contribs) at 07:37, 27 April 2022 (Importing Wikidata short description: "Block cipher" (Shortdesc helper)). The present address (URL) is a permanent link to this version.

(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)
Q
General
DesignersLeslie McBride
First publishedNovember 2000
Derived fromAES, Serpent
Cipher detail
Key sizes128, 192, or 256 bits
Block sizes128 bits
StructureSubstitution–permutation network
Rounds8 or 9
Best public cryptanalysis
A linear attack succeeds with 98.4% probability using 297 known plaintexts.[1]

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 vulnerable to linear cryptanalysis; Keliher, Meijer, and Tavares have an attack that succeeds with 98.4% probability using 297 known plaintexts.[1]

References

[edit]
  1. ^ a b L. Keliher, H. Meijer, and S. Tavares (12 September 2001). High probability linear hulls in Q. Proceedings of Second Open NESSIE Workshop. Surrey, England. Retrieved 2018-09-13.{{cite conference}}: CS1 maint: multiple names: authors list (link)
  2. ^ Eli Biham, Vladimir Furman, Michal Misztal, Vincent Rijmen (11 February 2001). Differential Cryptanalysis of Q. 8th International Workshop on Fast Software Encryption (FSE 2001). Yokohama: Springer-Verlag. pp. 174–186. doi:10.1007/3-540-45473-X_15.{{cite conference}}: CS1 maint: multiple names: authors list (link)