CYPHER.BA CYPHER.BA enciphers and deciphers Text (.DO) files on the Tandy Model 100, 102 and 200 computers. CYPHER only works on and between these three computers. It is user-customizable, which deters others, even with another version of CYPHER, from decoding your files. You may use it to encipher files which stay in RAM or are to be saved on cassette or disk, such as ADRS.DO or NOTE.DO, or you may wish to scramble messages sent via Email over networks such as CompuServe. CYPHER is not intended to place scrambled messages on the message board; most Sysops frown on this in any case. CAVEAT: Text files to be enciphered must contain only characters between ASCII 32 and 123, ASCII 125 ("}"), TABs and end-of-paragraph markers (ASCII 13 + ASCII 10). Any characters above 126 or below 32 will be converted to spaces and you will hear a short beep. Do NOT use "~" (SHIFT GRPH [) or "|" (SHIFT GRPH -) in your Text files, as they will be translated into spaces, tabs or end-of-paragraphs. CYPHER.BA (in .DO form) and CY-REG.DO (see CY-GEN.BA in CYPHER.DO2) are in a form which can be encoded by CYPHER but CYPHER.DOC cannot, as it contains both of these characters in this paragraph. Also, do NOT use a SPACE followed by a TAB, as this will be deciphered into an end-of-paragraph. Use two tabs instead. You may use a TAB followed by a space. USING CYPHER.BA There are five steps to using CYPHER: 1) You are first asked for a filename. CYPHER only enciphers or deciphers Text (.DO) files. 2) The first 25 characters of the file are then displayed, and CYPHER asks you whether you want to "eNcode or Decode" it. Just press "N" or "D". You can, by the way, press F8 to abort the program at any time until the coding actually begins. 3) You are then asked how many LEVELS of coding you require. This refers to the number of times you want to run the file through CYPHER. You can specify from 1 to 9 levels - the more you use the more difficult the coded file is to decipher. When Decoding the file you must use the same number of levels used when eNcoding it. If you are Decoding, you are then asked if this is the FINAL decode. You can, if you wish, run the file through several different CYPHER programs (e.g. CYPH-A and CYPH-B) with different "registers" (see CY-GEN.BA). Or you may run the file through the same CYPHER program using different keywords. If you do run the file through CYPHER several times using different keywords or registers, then only the last level of the LAST run-through contains the Final Decode, so only type "Y" for the last run-through (which you expect to result in the decoded message). 4) The next screen consists of a question mark followed by five spaces. Here you enter the first "KEYWORD", which is a NUMBER up to 32766. The larger the number you use, the greater time penalty you'll pay (see RUNNING SPEED below). If you enter a number greater than 32766, then you'll get an "?OV Error in 24" message. Don't worry, just RUN the program again. As with the number of levels, when Decoding you must enter exactly the number that was entered when the file was eNcoded. 5) You will then see a screen with 94 marked spaces and six vertical lines which are intended as a visual aid to entering the KEYWORD string. You can choose any combination of up to 254 characters - upper or lower case being significant. Again, if you are Decoding then you must enter the same keyword string that was entered when the file was eNcoded. This may seem complicated, but you'll find that it requires few keystrokes. After the computer has finished, it emits a high-pitched beep and returns to the main menu. NOTA BENE: If the file was run through CYPHER several times, then to Decode it you've got to reverse the order it is run through. For instance: program FINAL Decode? levels key-1 key-2 ------- ------------- ------ ----- ----- To eNcipher: 1) CYPH-A 6 1234 abc 2) CYPH-B 1 555 Hello To Decipher: 1) CYPH-B No 1 555 Hello 2) CYPH-A Yes 6 1234 abc The more complicated you make the eNcoding process, the more difficult the enciphered file will be for others to decrypt. However, the tradeoff is that it will become more time-consuming for _you_ to encipher and decipher. RUNNING SPEED As mentioned above, the first "keyword", which is a number, delays the program based on the size of the number. Entering 100 will add around one second to the setup time, 1000 will add 14 seconds, 10000 adds 136 seconds, and 32766 adds 446 seconds. But the higher the number the more difficult decrypting should be. The remainder of the setup time takes from 10 to 15 seconds for internal calculations. The actual encoding averages about 1185 characters per minute on the Model 100, or 1125 cpm on the Tandy 200. Non-final Decodes run at 1040 (M100) or 970 (T200) cpm; and the Final Decode runs about 835 or 785 cpm. ENCODED FILES You should not alter a file encoded by CYPHER. If the file is sent over a network via TELCOM, there likely will be added end-of-paragraph markers and possibly spaces and tabs. Don't worry about any of these when decoding. However, when there is some header information such as: < Date: 08-Oct-87 08:01 PDT< From: James A. McGreevy [70206,1115]< Subj: CYPHER.BA< < < then the characters MUST be deleted before you can decode the following message. You can paste them temporarily in another file if you want to copy them back to the decoded message. There must be no _characters_ at the beginning of the file that were not there when the file was encoded. However, if the file has footer information such as: < < < Last page. Enter command< or to continue! < deleting these characters is optional as none of the coded message follows and thus is not affected. If you leave them in they will be interpreted as garbage at the end of the file. --- James A. McGreevy, CompuServe #70206,1115