Patent ID: 7627121

Claim:
A method of validating the integrity of a data packet transmitted from a transmitter to a receiver for stream cipher out-of-synchronization detection, the method comprising: receiving a data packet to be transmitted from a network layer of a protocol stack of the transmitter, the data packet including a payload and a network layer checksum; generating a checksum based on the payload of the received data packet; comparing the generated checksum with the network layer checksum included in the data packet; encrypting the data packet by a security layer of the protocol stack of the transmitter if the checksums match, the security layer being a lower layer compared to the network layer in the protocol stack of the transmitter; transmitting the encrypted data packet by the transmitter to the receiver; decrypting, by a security layer of a protocol stack of the receiver, the encrypted data packet containing the network layer checksum and the payload, the network layer checksum included in a header of the data packet and based upon the payload, the decrypting accomplished using a forward cipher key; extracting the network layer checksum from the decrypted data packet; calculating a calculated checksum for the data packet based on the payload of the data packet; comparing the network layer checksum extracted from the decrypted data packet with the calculated checksum at a checksum validation engine; and detecting a loss of stream cipher synchronization if the calculated checksum does not match the network layer checksum extracted from the decrypted data packet.