| 摘要 |
<p>The invention concerns a cryptographic method for transferring messages in encrypted form between two media A and B sharing a secret number E and hardly reversible functions fI(fJ (x)) = fJ(fI(x)). The method operates without public key and without shared private key through a dialogue consisting of several message exchanges. If the medium A wishes to exchange confidentially the message M1 with the medium B, the medium A randomly draws a number A1 and sends to B the number fE(fA1(M1)) = M2. B randomly draws B1 and calculates fB1(M2) = M3 which it sends to A. A calculates the reciprocal A1prime(=g(A1)) of A1 such that, A sends back to B fA1prime (M3) = M4. B calculates the reciprocal of B1prime=g(B1*E) of B1*E then calculates fBprime(M4)=(M5). Since M5=M1, the message has been exchanged confidentially. In another embodiment, A and B share a secret S, the message M1 comprises the secret S and B authenticates A by verifying whether M5 actually consists of the secret S. The invention is applicable in the case of a microprocessor card, a micro-computer and an electronic wallet.</p> |
