Differential Cryptanalysis, the main chosen-plaintext attack on DES-like cryptosystems, uses iterative characteristics for cryptanalyzing variants of DES with an arbitrary number of rounds.
This thesis extends the scope of finding iterative characteristics of DES variants thereby improving the chances of getting better iterative characteristics.
We have implemented the algorithms for finding different methods of iterative characteristics and experimented on DES-like cryptosystems. We also experimented on standard DES but we could not get better iterative characteristics. We also showed that a modification of the P-box permutation or expansion permutation in the standard DES can make the attack more successful.
Full Thesis (PS-gzipped: 116K)