The second computer system receives an encrypted message from {TAIL ~ the first computer system} and processes {HEAD ~ the encrypted message} to generate a response message 
The second computer system receives an encrypted message from { TAIL ~ the first computer system } and processes { HEAD ~ the encrypted message } to generate a response message
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH