Ciphers are methods of transforming information to conceal its meaning or structure. This organizes ciphers by their method, providing direct access to explanations, history, and practical usage for each technique.
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Book Ciphers
book and steganographic ciphers encode messages using external texts, such as books or documents, as keys.
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Mechanical Ciphers
mechanical or composite ciphers apply multiple transformations, often using devices or algorithmic systems to automate encryption.
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Modern / Complex Ciphers
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Polyalphabetic Ciphers
polyalphabetic ciphers use multiple substitution alphabets to encrypt plaintext, cycling through different mappings according to a key or repeating sequence.
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Polygraphic Ciphers
polygraphic or fractionation ciphers encrypt plaintext in blocks (digraphs, trigraphs) or by splitting letters into coordinates before recombining.
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Substitution Ciphers
substitution ciphers replace plaintext symbols with ciphertext symbols according to a fixed mapping. each symbol is replaced by another symbol, letter, number, or glyph, either directly or via a keyed alphabet.
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Transposition Ciphers
transposition ciphers rearrange the order of plaintext symbols without changing the symbols themselves. security comes from permutation rather than substitution.