Frequency Analysis client-side
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How to use Frequency Analysis

Frequency analysis counts the distribution of a text's letters and displays it as a chart, along with the most common bigrams (pairs) and trigrams (triplets). It then compares the resulting profile to the expected frequencies of English or French. It's the first weapon of classical cryptanalysis: in a substitution cipher, the most frequent letter of the ciphertext very often corresponds to the plaintext E. Pair this tool with the substitution solver to crack a cryptogram. Everything is computed in your browser.

Letter, bigram and trigram frequency.

FréquenceCryptanalyseLettresStatistics

How to use Frequency Analysis

Frequency analysis counts the distribution of a text's letters and displays it as a chart, along with the most common bigrams (pairs) and trigrams (triplets). It then compares the resulting profile to the expected frequencies of English or French. It's the first weapon of classical cryptanalysis: in a substitution cipher, the most frequent letter of the ciphertext very often corresponds to the plaintext E. Pair this tool with the substitution solver to crack a cryptogram. Everything is computed in your browser.

Frequently asked questions

Why does letter frequency help decrypt?

Each language has a signature: in English, E is by far the most frequent letter. In a substitution cipher this signature is preserved, revealing the likely mappings.

What are bigrams and trigrams?

Pairs (TH, HE, IN) and triplets (THE, AND, ING) of consecutive letters. Their frequencies are also characteristic of a language and refine the analysis.