Identification of N Block Ciphers

This paper proposes a mechanism to identify n-block ciphers in ECB and CBC mode of operation, from patterns found on a set of cryptogams. This result demonstrates the existence of intrinsic properties in mathematical models of the ciphers, which create a signature in cryptograms. Based on unsupervised categorization technique, experiments are performed on a set of cryptogams which were enciphered by the finalist algorithms of AES contest: MARS, RC6, Rijndael, Serpent and Twofish (particular case of n = 5); with 128-bit key. The processes of clustering and categorization used were successful, allowing 100% of precision in ECB mode. The CBC mode reached 100% of precision in clustering, although it failed in the categorization process. Finally, the paper presents the propositions and its respective proofs which this methodology holds for any value of n.