Traceable method and system for encrypting and/or decrypting data, and recording media therefor

Traceable system for encrypting and/or decrypting broadcast data capable of identifying a traitor, among different lawful users, who has communicated secret data to a non-authorized third party so that this third party is able to encrypt and/or decrypt the broadcast data, this system comprising:

• a transmitter able to encrypt broadcast data, this transmitter being capable of applying at least a first secret cryptographic function, to directly process a message, then of broadcasting the message,
• several decoders able to decrypt broadcast data, all the decoders being able to apply a second secret cryptographic function identical to said first function or to its inverse for the direct processing of said broadcast message, each decoder for this purpose being equipped with a memory in which a mathematical description of said second function is recorded;
• wherein the memory of each decoder contains a mathematical description of said second function different from the one recorded in the memory of the other decoders or in the memory of the other groups of decoders so that this mathematical description exclusively identifies the particular decoder or group of decoders among all the decoders.