Linear Cryptanalysis Against Block Ciphered System Under Noisy Ciphertexts
In this paper, the authors study the effect of channel errors on the performance of linear cryptanalysis against block ciphered system. They study DES block cipher working in Cipher FeedBack mode (CFB) as a special case. In their model, eavesdropper launches linear attack by querying an oracle which provides with corrupted ciphertexts over a Binary Symmetric Channel (BSC). A new verification strategy in linear attack has been designed and numerically optimized to allow Eve to mount a successful attack in noisy environments. However, they show that even by utilizing this optimized strategy, there is still possibility of mis-detection in Eve's cryptanalysis, which directly depends on the channel degradation level.