A Key Recovery Algorithm Using Random Key Leakage from AES Key Schedule

A key recovery algorithm using parts of the key schedules is proposed for evaluating the threat of probing attack. Suppose that we have an information leakage sensor, and we can detect a leak (attacked) point where an attacker makes electrical/physical contact with a laser, a probe, etc. We assume that the attacked bits (leaked bits) are completely known to the attacker, whereas the other non-attacked bits are not leaked at all. We also assume that each bit leaks with a constant probability. Our key recovery algorithm is constructed by modifying the pruning phase that for cold boot attacks proposed by Tsow. Experimental result shows that, using our algorithm, more than 15% leakage recovers the key with almost probability 1, whereas less than 10% is recovered with small probability close to 0.