A substitution cipher is one where one letter becomes another throughout. For example, turning "SASSAFRAS" INTO "XAXXAFRAX" substitutes "X" for "S". Julius Caesar used a cipher similar to this for his official communications.

Instructions:

1) To operate this applet, you first need to set up which letter changes into which. The letters with lines between them can be dragged onto each other. You can drag a letter from the top onto the bottom or bottom to top. The top row represents letters from the top box. The bottom row represents letters from the bottom box.

2) Enter text you want to encrypt in the top box, or text you want to decrypt in the bottom box.

3) Press the "Encrypt" graphic to transfer text from the top box to the bottom, passing through the encryption scheme. Or press the "decrypt" graphic to pass text from the bottom box to the top, passing through the encryption box the other way.

The box of letters at the bottom is a way to manually set the code used to encrypt and decrypt. This is useful if you want to write down what you used to encrypt, give the key to a friend, etc. To set a code manually, enter it in the box and press the "SET" button. If you want to try using the code Julius Caesar did, enter "XYZABCDEFGHIJKLMNOPQRSTUVW" into the box, and press set.
 

THIS IS EXTREMELY INSECURE ENCRYPTION.
DO NOT USE IT TO PROTECT VALUABLE INFORMATION.
 

Applet written by Team 28005 for use exclusively on this site.