Fault-based analysis of flexible ciphers

• Main Authors: V.I.Korjik, A.Mukherjii, M.A.Eremeev, N.A.Moldovyan
• Format: Article
• Language: English
• Published: Institute of Mathematics and Computer Science of the Academy of Sciences of Moldova 2002-07-01
• Series: Computer Science Journal of Moldova
• Subjects: Flexible cipher; block cipher; differential fault analysis
• Online Access: http://www.math.md/nrofdownloads.php?file=/files/csjm/v10-n2/v10-n2-(pp223-236).pdf

We consider security of some flexible ciphers against differential fault analysis (DFA). We present a description of the fault-based attack on two kinds of the flexible ciphers. The first kind is represented by the fast software-oriented cipher based on data-dependent subkey selection (DDSS), in which flexibility corresponds to the use of key-dependent operations. The second kind is represented by a DES-like cryptosystem GOST with secrete S-boxes. In general, the use of some secrete operations and procedures contributes to the security of the cryptosystem, however degree of this contribution depends significantly on the structure of the encryption mechanism. It is shown how to attack the DDSS-based flexible cipher using DFA though this cipher is secure against standard variants of the differential and linear cryptanalysis. We also give an outline of ciphers RC5 and GOST showing that they are also insecure against DFA-based attack. We suggest also a modification of the DDSS mechanism and a variant of the advanced DDSS-based flexible cipher that is secure against attacks based on random hardware faults.