Patent ID: 7925010

Claim:
A method, comprising: a) associating a single joint identity with first and second electronic devices which identifies a common entity that is formed by the first and the second electronic devices, the single joint identity identifying the common entity to a transmission device, the first electronic device being associated with a first trusted authority, and the second electronic device being associated with a second trusted authority; b) executing, by the transmission device, a single encryption operation of a message in clear by using the single joint identity so as to encrypt said message and transmitting the encrypted message simultaneously to the first and the second electronic devices; c) generating, by the first and the second electronic devices a first decryption token and a second decryption token, respectively, said first and second decryption tokens being obtained based on quantities provided by at least said first trusted authority, said quantities being calculated from random numbers, public keys, and master keys; d) providing said first decryption token to the second electronic device and said second decryption token to the first electronic device; and e) generating, by starting from said first and second decryption tokens, by the first and second electronic devices, a joint decryption key in order to decrypt the encrypted message, wherein the second electronic device is not associated with said first trusted authority and the first electronic device is not associated with said second trusted authority, said second trusted authority being distinct and autonomous with respect to said first trusted authority.