Mutual authentication/cipher key distribution system

A mutual authentication/cipher key distribution system, wherein a communication network and all users belonging thereto have devices for implementing a common key cryptosystem,

• an identifier of a user i represented by ID.sub.i is made public in the network,
• an authentication key of a user i represented by S.sub.i is known only to the network and the user i,
• the identifiers and authentication keys of all the users are stored in a database of the network, and
• a random number which is created by a verifier to authenticate a prover and sent to him and a random number which is created by the prover are processed by the prover using specific functions, and
• the resulting values are encrypted by the prover and sent back to the verifier, thereby making impossible a chosen plaintext attack on the encryption algorithm used.

A mutual authentication/cipher key distribution system, wherein a communication network and all users belonging thereto have devices for implementing a common key cryptosystem,

• an identifier of a user i represented by ID.sub.i is made public in the network;
• an authentication key of the user i represented by S.sub.i is known only to the network and the user i,
• the identifiers and authentication key of all the users are stored in a database of the network, and
• a user first presents his identifier (ID) to the network by simultaneously sending thereto data for the authentication of the user by the network and data for the authentication of the network by the user and then up to three interactions take place between the network and the user to complete the authentication of the user by the network and the authentication of the network by the user.

A mutual authentication/cipher key distribution system, wherein a communication network and all users belonging thereto have devices for implementing a common key cryptosystem,

• an identifier of a user i represented by ID.sub.i is made public in the network,
• an authentication key of the user i represented by S.sub.i is known only to the network and to the user i,
• the identifiers and authentication key of all the users are stored in a database of the network, and
• a user presents his identifier (ID) to the network by sending therefrom to the user data for authentication and encrypted data of a cipher key for the subsequent privacy communication and then up to three interactions take place between the network and the user to complete the authentication and the distribution of the cipher key for cipher communication.