Patent ID: 8850203

Claim:
A method for performing an authenticated key agreement protocol, in accordance with a multimedia communication system, between a first party at a first computing device and a second party at a second computing device, the method at the first party comprising steps of: obtaining at least one private key for the first party from a key service at a third computing device; sending a first message comprising an encrypted first random key component from the first computing device to the second computing device, the first random key component having been computed at the first computing device, and the first message having been encrypted using a public key of the second party in accordance with an identity based encryption operation; receiving a second message comprising an encrypted random key component pair at the first computing device from the second computing device, the random key component pair having been formed from the first random key component and a second random key component computed at the second computing device, and the second message having been encrypted at the second computing device using a public key of the first party in accordance with the identity based encryption operation; decrypting the second message using the private key obtained by the first computing device from the third computing device to obtain the second random key component; sending a third message comprising the second random key component from the first computing device to the second computing device, the third message having been encrypted using the public key of the second party in accordance with the identity based encryption operation; and computing at the first computing device a secure key based on the second random key component, the secure key being used for conducting at least one call session with the second party via a media plane of the multimedia communication system; wherein the first message, the second message and the third message comprise respective messages of an end-to-end key exchange between the first party and the second party—communicated in the media plane of an Internet Protocol Multimedia Subsystem; and wherein the first message is an INVITE message associated with the Internet Protocol Multimedia Subsystem.