Mono-Alphabetic Substitution Cipher Tools

This page contains most of the tools that you need to write or break mono-alphabetic substitution ciphers. That is ciphers which use one alphabet only to substitute for the plaintext alphabet.
Paste the block of text that you want to manipulate into the "Plaintext" box. Then hit the relevant button. If you want to perform more than one operation then hit the "Move to Top" button.
Tooltips will appear if you hover over a control.
If you can read JavaScript then download the source and fiddle with it! Javascript Code

Plaintext

Manipulated text

Substitution and Shift Ciphers



Random Substitution
Codeword
WRONGABCDEFHIJKLMPQSTUVXYZ
WRONGHIJKLMPQSTUVXYZABCDEF

Guessing Tools


Plaintext letter=
Ciphertext letter=

Enter a plaintext letter and the corresponding ciphertext letter. Then press 'Enter Letters'. This should put the letters into their correct relationship in the cipher window.
Trial decode will leave ciphertext letters unchanged if they have no plain text value. Test letters will be decrypted into lower case.

Affine a b

C1 = aP1 + b
C2 = aP2 + b
C1-C2 = a (P1-P2)
a=(C1-C2)/(P1-P2)

C = cipher text letter.
P = plain text letter.

Further notes on affine shift ciphers.

Parallel Decoding

This tool tries all 26 simple shift ciphers against the first 25 letters of the ciphertext. This should enable you to spot a message that has been enciphered by a simple shift cipher.

Frequency Analysis Results

Graphic Frequency Analysis.