Method for secret protection in group key initial allocation

A method for secret protection in group key initial allocation belongs to the field of information safety. The method is implemented in three stages which are a group key issuing stage, a group key verification stage and a third party certification stage respectively. In the group key issue stage, an issuer of a group key encrypts a group key message with a public key, performs directed signature on a group key message with a private key and the public key and transmits a message cipher text and the signature to an applicant joining in the group for the first time. In the group key verification stage, the applicant joining in the group for the first time decrypts the message cipher text with the private key and verifies the signature of the group key message with the public key and the private key. In the third party certification stage, the applicant joining in the group for the first time proves the validity of the signature of the group key message through a zero-knowledge proof mechanism to a third party without revealing any private information to the third party. Through the method, safety complexity is increased by the method of associating random number binding encryption with the signature, and a directed signature mechanism is introduced to ensure that only the applicant joining in the group for the first time can certificate the validity of the signature of the group key message.