In response, {HEAD ~ the first computer system} generates {TAIL ~ a message}, encrypts the generated message, and transmits the encrypted message to the second computer system 
generates
In response , { HEAD ~ the first computer system } generates { TAIL ~ a message } , encrypts the generated message , and transmits the encrypted message to the second computer system
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH