Patent ID: 7843910

Claim:
A method of decoding a data packet which conforms to an internetworking protocol and encapsulates by means of an encapsulation security protocol an enciphered UDP datagram which includes an UDP header and a payload, the data packet having an network protocol header and a security protocol header, comprising: obtaining from said network protocol header an network protocol source address, an network protocol destination address and a network protocol identification; commencing a decipher of said enciphered UDP datagram; obtaining at the commencement of the decipher a length field from said UDP header; establishing a pseudo-header for inclusion in a UDP checksum, said pseudo-header including said network protocol source address, said network protocol destination address, said network protocol identification and said length field; continuing the decipher of said enciphered UDP datagram in parallel with computing said UDP checksum; and accepting or rejecting said data packet after examination of said UDP checksum.