mirror of
https://github.com/TheAlgorithms/Ruby
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33 lines
761 B
Ruby
33 lines
761 B
Ruby
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# Caesar Cipher replaces characters rotating X number of positions to the left or to the right.
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#
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# Alphabet
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# a b c d e f g h i j k l m n o p q r s t u v w x y z
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#
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# shift 4 >> it means to rotate 4 places
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#
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# After shifting
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# e f g h i j k l m n o p q r s t u v w x y z a b c d
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#
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# plaintext -> apple
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# ciphertext -> ettpi
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class CaesarCipher
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ALPHABET = ('a'..'z').to_a
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def self.encrypt(plaintext, shift)
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plaintext.chars.map do |letter|
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temp = letter.ord + shift
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temp -= ALPHABET.length while temp > 'z'.ord
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temp.chr
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end.join
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end
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def self.decrypt(ciphertext, shift)
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ciphertext.chars.map do |letter|
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temp = letter.ord - shift
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temp += ALPHABET.length while temp < 'a'.ord
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temp.chr
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end.join
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end
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end
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