| 摘要 |
According to the invention, a public key (PK) depending on a secret key is accessible to an emitter entity (2) and to receiver entities. A private key, that can be associated with a receiver entity, depends on the secret key and on an identity parameter (ID<SUB>j</SUB>) of said entity. The encryption of a message (M) intended for a set of s receiver entities (s > 1 ) comprises generating a symmetrical encryption key (K) and an associated cryptogram (Hdr) based on the public key, identity parameters of the s receiver entities and a number selected by the emitter entity. The cryptogram provides access to the associated encryption key by combination with the public key, the identity parameters of the s receiver entities and the private key of an identified receiver entity of the set. The message is encrypted in the emitter entity by the generated encryption key, and broadcasted in this encrypted form together with said cryptogram. |
