44 lines
902 B
Plaintext
44 lines
902 B
Plaintext
= Substitution =
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A Cipher where characters are replaced based on a mapping
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== Monoalphabetic Subsititutions ==
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Cipher where each occurrence of a plaintext symbol is replaced by a
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corresponding ciphertext symbol
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=== Afline ===
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An affine cipher E(x) = (ax + b) MOD 26 is a monoalphabetic sub cipher, where a
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and b are given constants
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=== Columnar Transposition ===
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Use letters to create columns, then fill all remaining columns with remaining
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letters in alphabetic order
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== Cryptoanalysis ==
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=== Monoalphabetic Substitution ===
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We make some assumptions
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* Its english and has same stats as standard english
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* word divisions are not preserved
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* use frequency analysis to guess high frequency letters
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- E E N O R I A S are 70% of letters in english
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* identify
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- vowels
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- diagraphs (common combos of letters ie TH)
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* Use cribs
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* guess and rely on luck
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== Also see ==
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* [[gcd]]
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[[index]]
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