Downloading and running the executable playfair.exe Create a new folder in a location you can find easily, called CryptoPrograms or something similar that you will easily recognize. Create another folder inside this one for the cipher type, e.g., Playfair. Now download the executable playfair.exe into this folder. You will also need to place a con in this folder, as a text file. This file should consist of the con itself as a continuous string with no spaces, and the tip in uppercase letters on the next line. You can start with the sample con file available for download from the same Computer Column folder on the ACA website that you got the playfair.exe file. For example, the sample con for the Playfair cipher is called E18MJ2010.txt. To run the program, double-click the executable, and a new window should open. It will give the name of the program and ask for the file name of the con. Before going further, I suggest that you customize the window as follows: 1. There is an icon just to the left of the title at the top left of the window. Clicking on this reveals a drop-down menu. Select the Defaults option. This opens another window called Console Windows Properties, which has 4 tabs. Change nothing in the General tab. 2. Click on the Font tab and choose Lucida Console, whose letters are easy to read than the other choice. 3. Click on the Layout tab. Increase both the window width and screen buffer width from 80 to 90, giving a slightly wider window. 4. Click on the Colors tab. Change the screen background from black to white and the screen text from white to black by clicking on the appropriate radio button and then on the desired color square. 5. When you have finished making the changes, click OK. These changes doen't take effect until after the window is closed and re-opened. To make the changes immediate, select Properties in the drop-down menu and make the same changes. You can make the window longer by dragging down on the lower right corner of the window. At the correct mouse position, a double-headed arrow control should appear. You can't make the window wider using this control. After customizing the window, go back to the program window, enter the name of the con file. If you made the con file using Notepad or another text editor, it will show up in the folder with the name you used when saving it. IMPORTANT: For these programs you must add the .txt extension when typing in the name. When the tableau comes up, proceed to solve the con, following the directions given by the program. All steps can be undone by entering 0 when it is given as an option. Quitting the program is accomplished by entering -1 when it is given as an option. If at some point you want to print out the display, you will need to prepare the window to highlight the part you want to print. To do this, follow these steps: 1. Click on the icon at the top left corner of the window and mouse down to Edit. 2. A second menu opens; select Mark. 3. Now use the mouse to highlight the portion of the window you want to print. This is done by selecting the area you want just as in a word-processing document. 4. Open the drop-down menu again, mouse down to Edit, and select Copy in the second menu. 5. Open a new document in Notepad. 6. In Notepad's Edit menu select Paste. The part of the window you highlighted should now appear in this Notepad document, and you can print it. When you are finished solving, enter -1 as directed by the program. The solution and square will be written to a text file called sol.txt, which you can look at later with Notepad by double-clicking it. Playfair solution hints: when you enter the desired case number, after the surviving cases are listed, you will see a list of letters that are in the same row and a corresponding list of letters in the same column. Use these in conjunction with the quads displayed for that case to build the Polybius square. Work this out on paper as best you can, and then enter letters in the square using the program. Any additional plaintext recovered will be shown. To use the Subtle Tip Search, valid digrams must appear in the cipher within an interval less than the tip length. In the example, we have, at digram 27: TC BW YX NG ZG ET in ds om et hi ng The digram pairs et/NG and ng/ET come from a rectangle in the Polybius square: E . N . . G . T