Patent ID: 6910129
Filing Date: 2005-06-21
Classification: G07C,H04L

Abstract:
1. A method of authenticating a remote party and establishing a cryptographic key for secure communications via an insecure communication channel, said method including the steps of: generating a first challenge signal of minimum duration T, where T is a fixed time interval and is larger than the channel transmission and processing delay; generating a random number x, computing g receiving a second ciphertext from said remote party; sending g receiving g receiving a third ciphertext from said remote party, stopping the clock after receiving the third ciphertext and computing an elapsed time interval of said clock; deriving a key k computing g decrypting said third ciphertext with the key k verifying that said elapsed time of the clock is within a predetermined interval (TL verifying that said second challenge signal is produced by said remote party; producing a second response signal of minimum duration T, encrypting said second response signal with the key k verifying that said first response signal is a response produced by said remote party to said first challenge signal; and after verifying that said second challenge signal and that said first response signal are produced by said remote party and that said elapsed time is within the predetermined interval, using a key k from g