Patent ID: 7222234

Claim:
A method for key agreement for a cryptographically secured point-to-multipoint connection between a server and a plurality of clients, comprising: altering, as a function of an identifier included in a first server message, a sequence of messages in a handshake initiating a secure socket layer protocol session, the identifier identifying the connection as an IP multicast connection; generating a MasterKey using the server, the MasterKey being used to generate a session key for encrypting application data; transmitting the MasterKey to a first client of the plurality of clients; wherein the first server message is a CertificateRequest message used to request a ClientCertificateType; and further comprising receiving the CertificateRequest message by the first client, and wherein, after the receiving, the altering is performed so that: a generation of the MasterKey by the first client is not performed and the first client transmits a client certificate to the server without sending a client ChangeCipherSpec message; the first client switches to encrypted transmission immediately after transmitting the client certificate to the server; the transmitting is performed by the server using a ServerMasterKeyExchange message, the MasterKey being encrypted with a public key of the first client; the server, after transmitting the ServerMasterKeyExchange message and after transmitting a server ChangeCipherSpec and a server Finished message, switches to a mode for encrypted data transmission; and the first client, after the server switches to the mode for encrypted data transmission, acknowledges the ServerMasterKeyExchange message received from the server by sending the client ChangeCipherSpec message and a client Finished message and switches to the mode for encrypted data transmission.