Paper 2003/003 Original: eprint.iacr.org/2003/003 ↗

Plaintext-dependant Repetition Codes Cryptanalysis of Block Ciphers - The AES Case

Abstract

This paper presents a new ``operational'' cryptanalysis of block ciphers based on the use of a well-known error-correcting code: the repetition codes. We demonstrate how to describe a block cipher with such a code before explaining how to design a new ciphertext only cryptanalysis of these cryptosystems on the assumption that plaintext belongs to a particular class. This new cryptanalysis may succeed for any block cipher and thus is likely to question the security of those cryptosystems for encryption. We then apply this cryptanalysis to the 128-bit key AES. Our results have been experimentallly confirmed with 100 {\bf effective} cryptanalysis. Our attack enables to recover two information bits of the secret key with only $2^{31}$ ciphertext blocks and a complexity of $\mathcal{O}(2^{31})$ with a success probability of 0.68.