Séminaire sécurité des systèmes électroniques embarqués

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Romain Poussier

Key enumeration & rank estimation for side-channel security evaluations

Cryptography is the basis of computer security. Altough the standard cryptosystems are secure when considered as mathematical entities, this does not hold anymore when it comes to real implementation. A device running a cryptographic algorithm is subject to so-called side-channel attacks (timing, power consumption, electromagnetic radiations...) which allow an attacker to obtain side informations on the secret key. In the case of block ciphers, these attack (often) follow a divide and conquer strategy where the attacker will target small independent parts of the key called subkeys. The final step of a full key recovery attack consists in mixing the information obtained on the different subkeys using a key enumeration algorithm. This talk will present how to perform such key enumeration and how to analyse the security against a full key recovery attack.