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#Kasiski Examination

2 articles with this tag.

Basic Classic Symmetric Breakers Intermediate

Breaking the Beaufort Cipher

The Beaufort cipher's reciprocal formula (C = K − P instead of Vigenère's C = P + K) looks like it should matter to an attacker. It doesn't: the same Kasiski examination, Index of Coincidence, and chi-squared pipeline that breaks Vigenère breaks Beaufort just as cleanly.

Aug 21, 2026 16 min read

A visual representation of the Vigenère Cipher Algorithm Breaker

Basic Classic Symmetric Breakers Intermediate

The Vigenère Cipher Breaking Guide

For three centuries the Vigenère cipher was called 'le chiffre indéchiffrable.' Learn the two statistical techniques, Kasiski examination and the Index of Coincidence, that finally broke it, and watch them recover a real key letter by letter.

Aug 14, 2026 17 min read

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