a time critical path comprising {HEAD ~ four serially connected sub stage units}, each sub stage unit being configured to perform a corresponding one of {TAIL ~ four MD5 operations} in the one stage of the MD5 process and each sub stage unit comprising: 
a time critical path comprising { HEAD ~ four serially connected sub stage units } , each sub stage unit being configured to perform a corresponding one of { TAIL ~ four MD5 operations } in the one stage of the MD5 process and each sub stage unit comprising :
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH