Patent ID: 7146009
Filing Date: 2006-12-05
Classification: H04L

Abstract:
1. A method for secure communication of a message M between a sender and a recipient, with the assistance of a key server, the method comprising: the sender obtaining a symmetric key Ks and encrypting the message M with the symmetric key Ks thereby forming an encrypted message Me; the sender encrypting the symmetric key Ks with a public encryption key Ke associated with the recipient thereby forming an encrypted symmetric key Kse; the sender forming first and second split-key fragments Kse the sender sending the second split-key fragment Kse the key server storing decryption key information, wherein the decryption key information is formed from the second split-key fragment Kse the sender transmitting to the recipient the encrypted message Me, the first split-key fragment Kse the recipient transmitting the key retrieval information Kr to the key server and receiving the decryption key information in response thereto; the recipient forming the encrypted symmetric key Kse from the first split-key fragment Kse the recipient decrypting the encrypted symmetric key Kse with a private decryption key Kd of the recipient thereby forming the symmetric key Ks; and the recipient derypting the encrypted message Me with the symmetric key Ks to read the original message M.