APPARATUS AND METHOD FOR CRYPTOGRAPHIC SYSTEM USERS TO OBTAIN A JOINTLY DETERMINED, SECRET, SHARED AND UNIQUE BIT STRING

摘要

Two users of a cryptographic system use the present invention when their respective processors need to get a jointly determined, secret, shared, and unique bit string. The present invention is effective and most useful when used over an insecure means of data transmission. After completion of the secret key exchange according to the present invention, the users proceed with further cryptographic exchanges which may use the jointly determined, secret, shared, and unique bit string produced by the present invention. The shared bit string produced by the present invention is a simple transformation of a sequence x0, x1, x2, ..., xt-1 produced by the "x2 mod N" pseudo-random number generator. Secrecy is achieved by disclosing selected information about this sequence, in such a way that the sequence can be computed by both participants in the secret key exchange but by no one else. It is a distinctive characteristic of the present invention to provide a means of cryptographic authentication of user A to the benefit of user B with no more processing and little more precautions than what is required for the secret key exchange only.