ISO/IEC 20008-2:2013 specifies anonymous digital signature mechanisms, in which a verifier makes use of a group public key to verify a digital signature. It provides - a general description of an anonymous digital signature mechanism using a group public key; - a variety of mechanisms that provide such anonymous digital signatures. For each mechanism, ISO/IEC 20008-2:2013 specifies - the process for generating group member signature keys and a group public key; - the process for producing signatures; - the process for verifying signatures; - the process for opening signatures (if the mechanism supports opening); - the process for linking signatures (if the mechanism supports linking); - the process for revoking group members.