Patent ID: 8464053

Claim:
A system that receives contents in a first Secure Real-time Transport Protocol (SRTP) transmission from a transmitter and that retransmits said contents in a second SECURE REAL-TIME TRANSPORT PROTOCOL (SRTP) transmission to a receiver, comprising: a device processor, said device processor being enabled to initialize, update, and maintain a rollover counter, and process at least one data unit by decrypting, translating, and re-encrypting said at least one data unit, wherein said device processor: receives as part of said first Secure Real-time Transport Protocol (SRTP) transmission said at least one data unit associated with a media session; determines a value of a rollover counter based on one of a 16-bit sequence number of said data unit in said first Secure Real-time Transport Protocol (SRTP) transmission, and a sequence number of a current maximum index of said data unit, wherein said sequence number of said maximum index is initialized to said sequence number of a first received data unit; determines an index of said at least one data unit based on a sequence number and said value of said rollover counter; determines a master key based at least on a <From,To>list, said list comprising two values that specify the range of indices within which a certain master key is valid; determines a session key of said media session using said determined index and said value of said rollover counter; and authenticates said at least one data unit using said session key; and retransmits said at least one data unit in said second Secure Real-time Transport Protocol (SRTP) transmission using said session key determined using said index and said value of said rollover counter from said first SECURE REAL-TIME TRANSPORT PROTOCOL (SRTP) transmission.