Chapter 3 of 4 · Cryptography 75%

🔑 The cipher called 'le chiffre indechiffrable' held for 300 years, until Babbage and Kasiski found one flaw. Can you spot the repeat that gives the key away?

A repeating key hides the letter E behind many faces, so frequency analysis stalls. But repeats in the ciphertext leak the key length. You'll run the Kasiski examination, recover the key, and decrypt the indecipherable cipher in minutes. 🗝️

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