A system for processing a data packet to determine if a replay condition exists for the data packet, wherein the data packet comprises a sequence number for comparison to a highest sequence number. The processing system includes a mask register to store a mask value, wherein the mask value provides an indication of prior receipt by the system of a plurality of data packets, and a shifter comprising an input coupled to receive the mask value from the mask register, wherein the shifter is operable to shift a binary value by a number of bit positions, the number determined by a difference between the sequence number and the highest sequence number.