CLUB 100 Library - 415/939-1246 BBS, 937-5039 NEWSLETTER, 932-8856 VOICE CRYPT.100 Documentation =========================== c1987 by Jon Diercks [73327,2353] CRYPT.100 is a machine language text file encoder/decoder for the Model 100. * It scrambles 7-bit ASCII text based on a keyword of any length. * It modifies the text file in place in the M100 menu, without creating a second file. This theoretically allows for coding of RAM files of up to almost 32K! * It ignores all spaces, carriage returns, control characters and 8-bit data, including any spaces or CR's added after encryption. * Best of all, it's FAST. No more waiting for a slow BASIC coder to putz along and crank out the correct file. For most small files, you won't know what hit you - coding seems almost instantaneous. * The keyword must all be alpha characters - CRYPT ignores whether they are upper or lower case. Finally, you must select ncrypt or ecrypt mode. As soon as CRYPT is done, you are returned to the M100 Menu . Simplicity itself! Tips: For total security, here's a few practices to follow... * Don't use special "cute" things in your file, like lines of dashes or equal signs or an asterisk at the beginning of each paragraph - they make it easy to find a pattern. Keep the amount of text to a minimum. Long files are easier to crack than short ones. * Spaces make it easier to decipher a coded file, soifyouwantyoucantakeallthe spacesoutlikethis, orjust takeso meofthe spaces outandmove themaround. * If you want to get really complicated, encode the file *twice* with two keywords of _different_ lengths. It doesn't matter what order, i.e. if you encode first with 'abc' then with 'wxyz', you can decode with either 'abc' or 'wxyz' first, as long as you do both. The effect is as if you encoded with a very long keyword, making it hard to detect a pattern. * _DON'T_ use keywords like 'abc' or anything less than three letters. * _DON'T_ insert or delete any *codeable* characters to the file after it's been coded. CRYPT will ignore spaces, CR's and control characters, but any letters or numbers will screw up the code. Enhancements: * Changed the code using some techniques I saw in QKRCHK.ASM. Main effect-- you don't have to type the '.DO' extension anymore. In fact, if you type the wrong extension, it will be ignored. * Changed the loader to allow for either relocating load OR loading to the ALT LCD buffer. Had to shorten some prompts to allow for this. ALT is the default location. * I already said not to use 'cute' lines of characters, but never, _NEVER_ use lines of @s or `s . They will show up as your keyword in the coded file! * Regarding EasyPlex/Forum mail or other BBS transmission of coded files--make sure that your coded file meets the line length specifications of whatever editor you use. If you upload a coded file with lines that are too long, characters may get chopped off the end of the line, thus putting the coded file out of sync with the keyword. I think these refinements make CRYPT pretty much complete . I would encourage others to write similar programs using the same algorithms for other computers . At any rate, I think I'm done with this for a while - at least till I come up with something better! Happy CRYPTing! Jon Diercks [73327,2353]