Free tool for analysis of cipher texts. This tool will help you get started solving your cipher, by doing statistical analysis and tests of your ciphertext. It will help you recognize several of the most common classic ciphers used in puzzles, crypto challenges, CTFs and geocaching mystery caches.
Text Analysis Tool
Any non-letters will be ignored.
- Text length:
- Word count:
- Minimum word length:
- Maximum word length:
- Average word length:
- Uppercase/lowercase percentages:
|Language||Chi Square Goodness of Fit|
This Chi Square Goodness of Fit Test will check the letter frequencies of your ciphertext against the expected letter frequencies of various languages. The lower the score, the better match. A value of less than 1.00 indicates a "probable hit". A missing value indicates that the text contains letters that shouldn't appear in that language (for example in English you shouldn't see the letter Ö).
In case there is a "hit", the cipher probably is a transposition cipher. You should then try these cipher types:
As with all statistics, the Chi Square Goodness of Fit Test depends on the text length. The longer text, the more reliable numbers you will get.
Caesar Shift Analysis
If any of the texts above looks like readable text, then you should try the Caesar tool:
Index of Coincidence
- Your Index of Coincidence1:
|Language||Index of Coincidence1|
1 This Index of Coincidence is non-normalized. For random English letters, this Index of Coincidence is 0.03846. In general it is 1 / number of letters in the alphabet. If you want to calculate the normalized Index of Coincidence, multiply the value with the number of letters in the alphabet (for example 26 for English).
If your text has an Index of Coincidence that matches a language, but the Chi Square value doesn't, it is a strong indication that your cipher is a monoalphabetic substitution cipher. You should then try these cipher tools:
- Cryptogram Solver (for Monoalphabetic Substitution Ciphers)
- Affine Cipher
- Atbash Cipher
- ROT13/ROT18/ROT47 Cipher
For further statistical analysis, the frequency analysis tool is recommended.
|Key Length||Index of Coincidence|
Polyalphabetic substitution ciphers can be detected by looking at each nth letter and calculating the Index of Coincidence. If the Index of Coincidence is lower, but spikes at around the reference value for a particular key length, it is a strong indicator that the cipher is a polyalphabetic substitution cipher.
In case you suspect a polyalphabetic substitution cipher, you should try these solvers: