A Generalization of Linear Cryptanalysis and the Applicability of Matsui's Piling-Up Lemma

Matsui's linear cryptanalysis for iterated block ciphers is generalized by replacing his linear expressions with I O sums. For a single round, an I O sum is the XOR of a balanced binary-valued function of the round input and a balanced binary-valued function of the round output. The basic attack is described and conditions for it to be successful are given. A procedure for nding e ective I O sums, i.e., I O sums yielding successful attacks, is given. A cipher contrived to be secure against linear cryptanalysis but vulnerable to this generalization of linear cryptanalysis is given. Finally, it is argued that the ciphers IDEA and SAFER K-64 are secure against this generalization. Keywords. Linear cryptanalysis, di erential cryptanalysis, piling-up lemma, IDEA, SAFER.

• Type: Conference
• Year: 1995
• Where: EUROCRYPT
• Authors: Carlo Harpes, Gerhard G. Kramer, James L. Massey
• Keywords: Balanced Binary-valued Function, Cryptology, EUROCRYPT 1995, Linear Cryptanalysis, Matsui's Linear Cryptanalysis