Patent ID: 7372856

Claim:
A method for Real-time Transport Protocol (RTP) packet authentication on a packet data network, comprising: providing a pseudorandom number generator (PRNG) for generating a plurality of pseudorandom numbers; exchanging a PRNG seed between an endpoint 1 and an endpoint 2 of the network; assigning one of the pseudorandom numbers to each RTP packet based on an RTP sequence number as an authentication tag on endpoint 1 ; attaching a given assigned pseudorandom number to each of the RTP packets on endpoint 1 , transmitting the packets to endpoint 2 ; generating, for each packet that is received at endpoint 2 , the pseudorandom number corresponding to the sequence number of each received packet; comparing, for each packet received at endpoint 2 , the generated pseudorandom number to the authentication tag included in the received RTP packet; and authenticating only those RTP packets having authentication tags which match the generated pseudorandom number; and when a sequence number of an RTP packet received at endpoint 2 is out of order because one or more proceeding RTP packets was dropped or delayed, iterating the PRNG multiple times so that the pseudorandom number generated corresponds to the sequence number in the received out-of-order RTP packet, the iterating function beginning with the sequence number of an RTP packet that was received at endpoint 2 in order, immediately prior to the one or more dropped or delayed RTP packets causing the out of order sequence number of the received RTP packet.