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