Protocols which use integrity protection often additionally require that an attacker cannot, for instance, gain information about the key by learning whether some (message, tag) combination is valid. The MAC game should additionally allow the adversary to make arbitrary queries of the form "is tag T valid for message M?" in order to capture this requirement.
Protocols which use integrity protection often additionally require that an attacker cannot, for instance, gain information about the key by learning whether some (message, tag) combination is valid. The MAC game should additionally allow the adversary to make arbitrary queries of the form "is tag T valid for message M?" in order to capture this requirement.