{HEAD ~ a second adder} configured to {TAIL ~ modulo} add an output of the fixed MD5 nonlinear function processing unit and the first adder 
{ HEAD ~ a second adder } configured to { TAIL ~ modulo } add an output of the fixed MD5 nonlinear function processing unit and the first adder
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH