Disk No: 2694                                                           
Disk Title: PC-Scrambler                                                
PC-SIG Version: S5.0                                                    
                                                                        
Program Title: PC-Scrambler                                             
Author Version: 5.0                                                     
Author Registration: $90.00                                             
Special Requirements: Hayes compatible modem.                           
                                                                        
PC-SCRAMBLER permits secure communications between two computer users.  
Using a modified version of the ``Exponential Key Exchange'' method,    
PC-SCRAMBLER sets up a secure communications link using a pseudo        
one-time pad based on an unpredictable random number generator.         
                                                                        
This method uses calculations based on a 200-digit number in the        
negotiation of the encryption key in a way that will frustrate any      
intruder, active or passive (e.g. phone tapper).  The encryption key    
used exists only in the computer, and only for the duration of the      
link.  The user does not need to remember it or even be aware of it.    
Unauthorized Read access to the program source code does not compromise 
the security of the method.  Nothing needs to be kept secret.  There are
no passwords to remember.                                               
                                                                        
A 25-digit random number is used to initialize the system.  The security
of the method depends entirely on the inability of any intruder to guess
this number.  Both ends of the communication use different numbers and a
new key will be generated for each new communication.                   
                                                                        
PC-SCRAMBLER works in conjunction with a Hayes-compatible modem.  Once  
communications is established and the key has been negotiated, the      
system enters ``chat mode,'' so the users can type messages to each     
another.  Fresh keystrokes appear in normal video, successfully         
transmitted keystrokes appear in reverse video.  Enter Voice            
Communications mode at any time with a single keystroke.  Return to     
Transmit mode when ready.                                               
                                                                        
PC-SCRAMBLER comes with full source code for inspection.                
                                                                        
PC-SIG                                                                  
1030D East Duane Avenue                                                 
Sunnyvale  Ca. 94086                                                    
(408) 730-9291                                                          
(c) Copyright 1991 PC-SIG, Inc.