Lesson plan
Q (cipher)
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. 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 2 97 known plaintexts.
Article summary
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. 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 2 97 known plaintexts.
Key claims
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.