New HMAC Message Patches: Secret Patch and CrOw Patch

Donghoon Chang, Somitra Kumar Sanadhya, Nishant Sharma

Abstract: At Asiacrypt 2012, Peyrin et al. showed generic attacks against the HMAC design. They utilized a pair of related keys where only the relation between the keys is known to the attacker but not the keys themselves (the secret key model). On similar lines, at Crypto 2012, Dodis et al. showed differentiability attacks based on ambiguous and colliding keys on HMAC in known/chosen key model. Peyrin et al. also proposed a patching scheme for HMAC and claimed that the proposed patch thwarts their attacks.