PGP :  pretty good privacy. 

 - beijing:   o reilly,   1995.  
 - paperback  
<br/><br/> 393pp., 23x18 
<br/><br/><label>ISBN: </label>1 56592 098 8 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Computers<br/>Cryptography<br/>electronic mail<br/>Privacy