Except explicit open source licence (indicated CC / Creative Commons / free), any 'Affine Cipher' algorithm, applet or snippet (converter, solver, encryption / decryption, encoding / decoding, ciphering / deciphering, translator), or any 'Affine Cipher' function (calculate, convert, solve, decrypt / encrypt, decipher / cipher, decode / encode. Rot-N/Rot cipher is a simple character substitution based on a shift/rotation of N letters in an alphabet. One letter is replaced by another (always the same) that is located further (exactly N letters further) in the alphabet. This is the basis of the famous Caesar code and its many variants modifying the shift.
This online tool breaks Vigenère ciphers without knowing the key. Besides the classical variant Beaufort ciphers and Autokey ciphers are supported as well.
As an example you can crack the following cipher text with this tool:
If you would like to know how this Vigenere breaker works have a look at the bits & bytes corner (German only).
If you want to break a monoalphabetic substitution cipher instead try the Substitution Solver.
Was gibt's Neues?
The Substitution Breaker is now Open Source
I finally decided to open source the implementation of the substitution breaker.
... and here comes support for Portuguese
This time both solvers have learnt to speak Portuguese.
Substitution Cipher Solver Tool
Solver: Support for Dutch added
Cipher Solver Tool
The Vigenere Solver as well as the Substitution Solver now speak one additional language: Dutch. Some work was required, as my favorite site does not provide ngrams for Dutch.