In operation, the authentication engine receives {TAIL ~ a request} having associated therewith {HEAD ~ a protect string} 
In operation , the authentication engine receives { TAIL ~ a request } having associated therewith { HEAD ~ a protect string }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD