Patent ID: 7590855

Claim:
A method, comprising: at a source node: cryptographically generating a first value relating to a communications packet which includes a packet header portion, the packet header portion including at least one field specified by a communications protocol to store protocol-specified packet header data having a value that falls within a predetermined numerical data range, scaling the cryptographically generated first value to fall within that predetermined numerical data range; and storing the scaled first value, instead of the protocol-specified packet header value, in the at least one field of the packet header portion of the communications packet; transmitting the communications packet from the source node to a destination/intermediary node; and at the destination/intermediary node where the communications packet is received: cryptographically generating a second value relating to the received communications packet and scaling that second value; extracting the scaled first value from the field of the packet header portion within the received communications packet; comparing the extracted scaled first value with the generated scaled second value; and authenticating the received communications packet as originating from the source node if the comparison indicates a match between the extracted scaled first value and the generated scaled second value.