Very fast and simple program, allowing the use of a real and powerful cryptography algorithm on 89 and 92+, using a 80 bits key.

Release 1.11, 05/20/2001.
Copyright 2001 by François LEIBER.

// Cryptography Algorithm PC1 ( Pukall Cipher 1 )
// (c) Alexandre PUKALL 1991
// Utilisation and modifications are free if the name of the author
// is included in the documentation.

1. Requirements
2. How to use PC1
3. History
4. Credits
5. Info

• A Ti-89 or a 92+ with any ROM or hardware, no kernel requirement.
  
  
• Program PC1, 1.2 KB.
  
  
• For easier use, also send to your calculator PC1.89g (or PC1.9xg for the 92+), and libraries Flib and Flib2.
  
  
• A few bytes free to run it :)
  

You can place pc1() and the rest in any folder, and I strongly suggest you archive everything.

• If it is already cryted, it tries to decode it. The advantage is that somebody else can't re-encode a variable who is already crypted, making it useless for the original user. Finally, the program tests to know if the key has a chance to be correct or no: if it has no chance to be correct, the program does nothing, otherwise it restores the variable to its state before encryption: this is made so somebody can't decrypt a variable using a wrong key, making it useless for the original user.
• In the other case, it encodes the variable, transforming it in a variable with the same name, but with type 'cryp'.

I've added all possible protections, the program should never crash.

The program's speed is about 2.5 KB/sec in coding-decoding.

PC1 automatically re-archives the variable after its coding-decoding.

• Interruptions are now disabled to speed up coding-decoding.
• A few lines of the source improved.
• The interface is now really finished.

v1.1 - 04/01/01 - 1 169 bytes

• Fixed a memory leak.
• Added informations in the Status Line.
• The program now automatically re-archives the variable after its coding-decoding.
• The program is compiled using the new release of TI-GCC : it is now smaller.
• I've also included a nice interface in BASIC using Flib, to make the use of PC1 even easier.

v1.0 - 02/20/01 - 1 237 bytes

• First release, nothing special to say.

• First, credits for the algorithm go to Alexandre Pullak, its author.
  
  
• A huge thank to the TIGCC team, especially Zeljko Juric for all his libraries and his very complete documentation of the different TIOS functions.
  
  
• Rusty Wagner for Virtual Ti.
  
  
• Jean Elchinger who sent me the algorithm source, and pushed me to port it to TI calculators.
  
  
• Me for Flib, so I could make very easily a nice interface :-)