Patent ID: 6697490
Filing Date: 2004-02-24
Classification: H04L

Abstract:
Apparatus comprising:means for receiving from a transmitter a) ciphered text generated as a function of a session key and crypto-sync information generated at said transmitter, along with b) a transmitter tag wherein said transmitter tag is a function of said session key and said crypto-sync information, a session key module for generating a local session key, a cryptographic synchronization module for producing and modifying local crypto-sync information, a decryption module wherein said decryption module uses said local session key and said local crypto-sync information for decrypting said ciphered text, a signature function module for generating a receiver tag wherein said receiver tag is a function of said local session key and said local crypto-sync information; and a comparator for comparing said receiver tag with said transmitter tag, said cryptographic synchronization module being configured for modifying said local crypto-sync information if said receiver and transmitter tags are different, said modifying being such as to make said receiver and transmitter tags the same, thereby allowing said apparatus to resynchronize with said transmitter.