XOR cipher

algorithms/ciphers/Xor.hs

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+module Xor
+    ( encodeB
+    , decodeB
+    , encode
+    , decode
+    ) where
+
+import Data.Char
+import Data.Bits
+
+-- Raw encoding function for lists of numbers
+-- First argument is the key, second is the data
+-- The key will be repeated to the length of the data
+encodeB :: Bits a => [a] -> [a] -> [a]
+encodeB key = zipWith xor (cycle key)
+
+-- Decoding is the same as encoding
+decodeB :: Bits a => [a] -> [a] -> [a]
+decodeB = encodeB
+
+-- To encode a String, we first map each character to a number,
+-- then map the numbers back to characters after encoding
+encode :: String -> String -> String
+encode key txt = map chr $ encodeB (map ord key) (map ord txt)
+
+-- Decoding is the same as encoding
+decode :: String -> String -> String
+decode = encode