Algebraic Structure Defectoscopy (ASD Tests)

We present a novel instrument of automated cryptanalysis suitable for measuring the number of rounds that can build one PRF round, so that 4 such rounds could be recommended as a Luby-Rackoff cipher secure against adaptive attacks. ASD tests can detect structural flaws in al l kinds of cryptographic primitives and their implementations. We present our results for some of the well-known ciphers and hash functions and for some of the eSTREAM candidates. Our tools can distinguish complete Achterbahn, Grain v1 and Grain-128 from random, detect weak keys in the complete IDEA cipher and find fata l structural flaws even in complete ciphers l ike LILI, KeeLoq or TEA in a matter of seconds. Cryptanalysts can save their valuable time by requiring that a l l new ciphers must pass not only randomness tests, but also automated cryptanalysis tests like ours before they could be considered interesting for manual cryptanalytic study.