Sliding Windows Succumbs to Big Mac Attack
- Cite this paper as:
- Walter C.D. (2001) Sliding Windows Succumbs to Big Mac Attack. In: Koç Ç.K., Naccache D., Paar C. (eds) Cryptographic Hardware and Embedded Systems — CHES 2001. CHES 2001. Lecture Notes in Computer Science, vol 2162. Springer, Berlin, Heidelberg
Sliding Windows is a general technique for obtaining an efficient exponentiation scheme. Big Mac is a specific form of attack on a cryptosystem in which bits of a secret key can be deduced independently, or almost so, of the others. Here such an attack on an implementation of the RSA cryptosystem is described. It assumes digit-by-digit computations are performed sequentially on a single k-bit multiplier and uses information which leaks through differential power analysis (DPA). With sufficiently powerful monitoring equipment, only a small number of exponentiations, independent of the key length, is enough to reveal the secret exponent from unknown plaintext inputs. Since the technique may work for a single exponentiation, many blinding techniques currently under consideration may be rendered useless. This is particularly relevant to implementations with single processors where a digit multiplication cannot be masked by other simultaneous processing. Moreover, the longer the key length, the easier the attacks becomes.