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3 articles with this tag.
ADFGVX fractionates each letter into two symbols and then shuffles them with a columnar transposition, the combination that made it Germany's toughest field cipher of 1918. This guide runs the modern automated attack: recover the transposition with the index of coincidence, then solve the substitution with quadgrams, and read a 330-letter message back out.
14 min read
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
