A dynamical systems approach to the discrimination of the modes of operation of cryptographic systems
This addresses the need for analyzing cryptographic system security, but it is incremental as it applies an existing dynamical systems approach to a new domain.
The paper tackled the problem of distinguishing cryptographic modes of operation by proposing an algorithm based on Lyapunov exponents to estimate divergence among ciphertexts, achieving the ability to differentiate among six modes using various block ciphers.
Evidence of signatures associated with cryptographic modes of operation is established. Motivated by some analogies between cryptographic and dynamical systems, in particular with chaos theory, we propose an algorithm based on Lyapunov exponents of discrete dynamical systems to estimate the divergence among ciphertexts as the encryption algorithm is applied iteratively. The results allow to distinguish among six modes of operation, namely ECB, CBC, OFB, CFB, CTR and PCBC using DES, IDEA, TEA and XTEA block ciphers of 64 bits, as well as AES, RC6, Twofish, Seed, Serpent and Camellia block ciphers of 128 bits. Furthermore, the proposed methodology enables a classification of modes of operation of cryptographic systems according to their strength.