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6 articles with this tag.
The Nihilist cipher turns letters into Polybius numbers and adds a repeating keyword, which makes it a Vigenere cipher wearing a numeric disguise. Index of coincidence finds the period, and column-by-column statistics peel off the key. This guide runs the real attack and recovers a 514-letter message.
13 min read
Bifid fractionates each letter into coordinates and shuffles them, which hides single-letter frequencies. Given the period, a hill climb over the Polybius square guided by English quadgram statistics peels the key apart anyway. This guide runs the real attack and recovers a 669-letter message.
13 min read
Learn about ADFGVX, the German WWI field cipher that combined Polybius-square fractionation with columnar transposition. It was considered so strong that French cryptanalyst Georges Painvin needed weeks to break a message that helped stop a 1918 offensive.
14 min read
Learn about the Bifid cipher, Félix Delastelle's fractionating cipher that scrambles a Polybius square's coordinates across an entire message, defeating single-letter frequency analysis far more thoroughly than plain substitution.
14 min read
Learn about the Nihilist cipher, the 19th-century Russian revolutionary cipher that turns a Polybius square into a polyalphabetic system by adding coordinate numbers together instead of shifting letters.
13 min read
Learn about the Polybius square, the ancient Greek cipher that turns every letter into a pair of coordinates. It became the foundation for tap codes, telegraph ciphers, and the ADFGVX cipher.
12 min read
