A Comparison between Two Off-the-Shelf Algebraic Tools for Extraction of Cryptographic Keys from Corrupted Memory Images

Abstract

Cold boot attack is a class of side channel attacks which exploits the data remanence property of random access memory (RAM) to retrieve its contents which remain readable shortly after its power has been removed. Specialized algorithms have been previously proposed to recover cryptographic keys of several ciphers from decayed memory images. However, these techniques were cipher-dependent and certainly uneasy to develop and fine tune. On the other hand, for symmetric ciphers, the relations that have to be satisfied between the subround key bits in the key schedule always correspond to a set of nonlinear Boolean equations. In this paper, we investigate the use of an off-the-shelf SAT solver (CryptoMiniSat), and an open source Grobner basis tool (PolyBoRi) to solve the resulting system of equations. We also provide the pros and cons of both approaches and present some simulation results for the extraction of AES and Serpent keys from decayed memory images using these tools.