Text Analysis Tool

Basic Statistics

• Text length:
• Word count:
• Minimum word length:
• Maximum word length:
• Average word length:
• Uppercase/lowercase percentages:

Language Detection

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:

• Columnar Transposition Cipher
• Double Columnar Transposition Cipher
• Railfence Cipher

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

Shift	Text

If any of the texts above looks like readable text, then you should try the Caesar tool:

• Caesar Cipher

Index of Coincidence

• Your Index of Coincidence¹:

Reference Values

Language	Index of Coincidence1
English	0.06506
French	0.07862
German	0.07180
Italian	0.07413
Portugese	0.07786
Spanish	0.07430
Swedish	0.05897

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.

Polyalphabetic Analysis

Key Length	Index of Coincidence

Polyalphabetic substitution ciphers can be detected by looking at each n^th 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:

• Vigenère Cipher
• Gronsfeld Cipher
• Beaufort Cipher