Pencil-and-paper ciphers, monoalphabetic substitution, polyalphabetic Vigenère grids, and transposition patterns.
1. Substitution Ciphers & Frequency Analysis
2. Polyalphabetic (Vigenère) & Grid Substitution
The Vigenère Cipher mitigates frequency analysis by using a keyword to shift letters. Each letter in the key determines the Caesar shift for the corresponding message letter. The key repeats to match the length of the plaintext.
Vigenère Formula: C_i = (P_i + K_(i mod len(K))) mod 26
3. Block and Transposition Ciphers (Playfair, Rail Fence, Hill)
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