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-
-
- What's a Substitution Cipher?
-
- A simple substitution cipher is one in which, for example, all
- the A's in the plaintext are replaced by R's, and all the B's are
- replaced by L's, and so on - so that no letter in the cipher text
- represents itself, and each letter in the ciphertext represents
- only one letter of plaintext. For example, if you see an X in the
- cipher text, you can be sure it can't stand for X in the plain-
- text; furthermore, if you determine that the X stands for a
- plaintext E, you can be sure that no other ciphertext letter also
- represents E.
-
- Ciphertext
-
- So where do you get the ciphertext to solve? Of course books and
- newspapers are good sources. And, if you want to generate your
- own ciphertext you can use the stand-alone program, ENC.EXE. It
- transforms its plaintext standard input into ciphertext standard
- output. You can use DOS redirection and an input file; or type
- the plaintext in from the console (ending with F6).
-
- i.e.:
- for file input:
-
- ENC <PLAIN.TXT >CIPHER.TXT
-
- for console input:
-
- ENC >CIPHER.TXT
-
- See your DOS manual for more about redirection.
-
- HELP
-
- Help Mode displays information on how to use SCU. Help Mode is
- activated by pressing the F1 function key. When Help Mode is
- active, the following keys perform certain functions:
-
- The ESCAPE key exits Help Mode, taking you back to SCU's Main
- Screen. If there are multiple pages on a particular topic,
- PAGEDOWN or PAGEUP brings up the next or previous help page.
-
- If there is at least one keyword on a page of help information,
- the ENTER key will cause a new help page, containing information
- about the keyword the cursor is on, to be displayed. If there
- are multiple keywords on a page, the ARROW keys will move the
- cursor to the various keywords so that they can be selected by
- the ENTER key.
-
- The Alt-F1 key combination brings back the previously displayed
- help page. Repeatedly pressing this key combination allows you
- to backtrack through the last 20 help pages you've seen.
-
- The F1 key takes you back to the Help Index.
-
-
-
-
- The CTRL-F1 key combination displays a summary of applicable
- keystrokes in Help Mode.
-
- Keywords
-
- Many help pages are displayed with certain words highlighted.
- These are topics about which SCU Help Mode has further informa-
- tion. A press of the ENTER key brings up a new help page with
- information on the selected keyword. If a help page has more
- than one key word, the selected keyword (the one about which more
- info will be displayed by a press of the ENTER key) is displayed
- in a block. Other keywords on the help page are merely high-
- lighted. You can select a different keyword on the page via the
- Arrow keys:
-
- RIGHTARROW or DOWNARROW select the next keyword;
- LEFTARROW or UPARROW the previous one.
-
- Invoking SCU
-
- To run this program, simply type SCU at the DOS command line.
- SCU will prompt you to enter the ciphertext; you can enter up to
- 240 characters of ciphertext including spaces and punctuation.
- Use the ENTER key to start a new line if the ciphertext is too
- long for one line. DOS will wrap-around and accept lines of up
- to 128 chars, but won't accept keystrokes after that, so hit
- ENTER at least every line and a half. You can use DOS's line
- editing keys (eg BackSpace) while typing. Enter a blank line
- (hit ENTER twice) to signal the end of the input. Alternatively,
- you can use your text editor, or DOS's COPY CON: FILENAME command
- to create a file containing the ciphertext. Then, run the prog-
- ram by typing SCU FILENAME and your ciphertext in the file FILE-
- NAME will automatically be loaded. FILENAME can be any valid DOS
- filename. SCU has one switch which specifies the path of the
- WordFind Dictionary file. If SCU is in the same subdirectory as
- the WordFind file, this switch doesn't have to be specified.
- However, if WordFind is in a subdirectory different from the one
- SCU is in, you must specify the different path via the command
- line switch so that SCU will be able to find the WordFind
- dictionary file. The full format, then, is:
-
- SCU -pPATHNAME CIPHER.TXT
-
- For example, SCU -p\GAME\WF CTEXT
-
- specifies that \GAME\WF will be searched and the ciphertext file
- is CTEXT. Put any switch options before the ciphertext filename.
- Of course, it would be tedious to invoke SCU that way every time,
- so you could set up a batch file, say SC.BAT, containing, for
- example:
-
- SCU -p\games\wf %1
-
- and then run it thusly:
-
-
-
-
- SC CTEXT
-
- See your DOS manual for more about batch files.
-
- SCU's Main Screen
-
- After invoking SCU, you'll see the top portion of the screen is
- devoted to the ciphertext and its solution. SCU can handle up to
- 240 characters of ciphertext including spaces and punctuation.
- Each 80 chars of the ciphertext entered results in a group of
- three lines: The bottom line is the ciphertext as entered; it's
- in lower case; this line never changes. The middle line is the
- plaintext only; it's in uppercase. The top line of the group is
- the plaintext in uppercase mixed with the ciphertext in lower-
- case. The middle portion of the screen shows the count of the
- ciphertext letters and the letters you have substituted. Remem-
- ber, the most commonly used letters in English (in order) are:
-
- ETAION SHRDLU
-
- The bottom line of the screen shows the results of pressing
- particular function keys.
-
- Function Keys
-
- F1 brings up the first Help page - the Help Index. From there,
- by selecting keywords, you can bring up information about certain
- aspects of SCU.
-
- F2 is the UnDo key. SCU remembers your substitutions into the
- ciphertext and undoes the most recent one with each press of the
- F2 key. By repeatedly pressing F2 you can undo all your
- substitutions.
-
- F3 allows you to shell to DOS. There you can run another program,
- presumably one which would aid in solving the ciphertext. This
- takes about 180k memory, plus the size of the program you run. To
- return to SCU, get back to the DOS command level and type EXIT.
-
- F4 spawns WordFind. You will be prompted to select the word to
- find; words matching the target word will appear in the WordFind
- window. Pressing any key will stop/start the scrolling. Be
- prepared to wait awhile if you select a target like ?????E? (a
- zillion words match it).
-
- F5 displays statistics reflecting the results of your efforts so
- far. The percentage figure is the ratio of the minimum number of
- substitutions required to solve the ciphertext compared to the
- actual number of substitutions made. No percentage is displayed
- until you've made at least the minimum number of substitutions.
- The time displayed is the time elasped beginning from the first
- substitution.
-
- F6 toggles the sound on and off.
-
-
-
-
- F8 loads a new puzzle file.
-
- F10 returns you to DOS.
-
- WordFind
-
- WordFind is a stand-alone shareware program that finds words
- which match a template. For example, if you know the word has 5
- letters, with the 1st and 4th letters being S and the 5th an E
- (S??SE) WordFind reports SENSE and SOUSE as matches. In SCU the
- template might look like SqxSE, with the ciphertext in lowercase
- and the plaintext in uppercase.
-
- For more information on WordFind contact:
-
- Castle Oaks Computer Services
- P.O. Box 36082
- Indianapolis, IN 46236-0082
- 317-823-6366
-
- SCU - Copyright (c) 1990, LeJac Marketing. All rights reserved.
-
- You can contact LeJac at:
-
- LeJac Marketing
- 3199 N. 800 West-Han
- Greenfield, IN 46140
-
- If you are using a non-registered copy of SCU, you should send in
- the registration fee of $10.00 to either of the above two ad-
- dresses.
-
- Attention International customers: The above registration fee is to be
- paid in U. S. Dollars, preferably by International Money Order. In
- addition to the registration fee, include $2.00 to cover additional
- postage that is required.
-
-