| 主权项 |
1. A cryptographic method for securely exchanging messages between at least two devices, each of them storing a shared secret key common to said devices, the method comprising:
generating a random number at each device; sending by each device the generated random number to the other devices; determining, at each device, a first key by calculating a first operation which uses both said shared secret key and each random number as operands; determining, at each device, a second key by encrypting a result of a second operation with a first algorithm using said first key as encryption key, said second operation using at least each random number as operands; determining, by one of said devices acting as a sending device, a pseudo message by calculating a reversible third operation which uses both said message and each random number as operands; calculating, by said sending device, a cryptogram resulting from the encryption of said pseudo message with a second algorithm using said second key as direct or indirect encryption key; transmitting said cryptogram from said sending device to at least one other device acting as receiving device; receiving said cryptogram at said receiving device; decrypting the cryptogram at the receiving device by using said second key as direct or indirect decryption key of said second algorithm to recover said pseudo message; retrieving said message from said pseudo message by reversing said third operation. |
