LAUSR

Key-recovery technology is often used by an adversary to attempt to recover the cryptographic key of an encryption scheme. The most obvious key-recovery attack is the exhaustive key-search attack. But modern ciphers often have a key space of size 2128 or greater, making such attacks infeasible with current technology. Cache-based side channel attack is another way to get the cryptographic key of an encryption scheme, but there are random noises in side channel attack. In order to reduce random errors, it is advisable to repeat the key recovery process many times. This paper is focused on the way to improve the key recovery accuracy by dealing with the key sequences obtained from the repeated Cache-based side channel attacks. To get the real key, private key bits from side channel attack are collected firstly. And then the key sequences are aligned using sequence alignment algorithms based on dynamic programming. The provided method of key recovery is universal, which is not limited to any cryptographic algorithm. The experiment shows that the proposed method has a good performance and a high availability when the error rate of the collected key bit is within a reasonable range.