In cryptography, Davies' attack is a dedicated statistical cryptanalysis method for attacking the Data Encryption Standard (DES). The attack was originally created in 1987 by Donald Davies. In 1994, Eli Biham and Alex Biryukov made significant improvements to the technique. It is a known-plaintext attack based on the non-uniform distribution of the outputs of pairs of adjacent S-boxes. It works by collecting many known plaintext/ciphertext pairs and calculating the empirical distribution of certain characteristics. Bits of the key can be deduced given sufficiently many known plaintexts, leaving the remaining bits to be found through brute force. There are tradeoffs between the number of required plaintexts, the number of key bits found, and the probability of success; the attack can find 24 bits of the key with 252 known plaintexts and 53% success rate.
Davies' attack can be adapted to other Feistel ciphers besides DES. In 1998, Pornin developed techniques for analyzing and maximizing a cipher's resistance to this kind of cryptanalysis.
Famous quotes containing the word attack:
“It is well worth the efforts of a lifetime to have attained knowledge which justifies an attack on the root of all evil—viz. the deadly atheism which asserts that because forms of evil have always existed in society, therefore they must always exist; and that the attainment of a high ideal is a hopeless chimera.”
—Elizabeth Blackwell (1821–1910)