Patent ID: 7840004

Claim:
A data communication system comprising two entities, each of said entities comprising a respective processor and having an entity short-term public key, an intra-entity shared key, and an entity long-term public key, at least one of said entities having a plurality of members, each member having a long-term private key and a corresponding long-term public key, said system being configured for generating a shared secret value between said entities by: for each entity having a plurality of members: (a) generating an entity long-term public key by combining the long-term public keys of all members of that entity; (b) generating a short-term private and a corresponding short-term public key for each of the members of that entity; (c) making said short-term public keys of members of that entity available to other members of that entity; (d) for each member of that entity: i. computing an intra-entity shared key by mathematically combining said short-term public keys of all said members of that entity; ii. computing an intra-entity public key by mathematically combining its short-term private key, the long-term private key, and said intra-entity shared key; and (e) combining intra-entity public keys of its members to derive an entity short-term public key; and (f) each entity making its intra-entity shared key and its entity long-term public key available to said other entity; and (g) each entity computing a common shared key by combining its entity short-term public key with the intra-entity shared key and the entity long-term public key received from said other entity.