Patent ID: 7079654

Claim:
A method for carrying out an electronic transaction across a communication network linking several entities comprising the following steps: a) a first entity builds a first message combining transaction data and calculates a first cryptogram of said first message using a first key system that said first entity shares with a last (n th ) entity; said first entity then links a second message with said first cryptogram and calculates a second cryptogram of said second message linked with said first cryptogram using a second key system that said first entity shares with an (n−1) th entity, and so on; said first entity links an (n−1) th message with an (n−2) th cryptogram previously obtained and calculates an (n−1) th cryptogram of said (n−1) th message linked with said (n−2) th cryptogram using an (n−1) th key system that said first entity shares with a second entity; said first entity then sends a last calculated cryptogram across the communication network; b) said second entity receives said last cryptogram, uses an appropriate key system to extract said (n−1) th message from said (n−1) th cryptogram containing said (n−1) th message, and sends said remaining (n−2) th cryptogram to a third entity, and so on; said n th entity receives said first cryptogram and uses an appropriate key system to extract said first message contained within said first cryptogram.