50 lines
1.5 KiB
Haskell
50 lines
1.5 KiB
Haskell
module Lib
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(
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createAlphabetFromText,
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encryptCaesar,
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decryptCaesar,
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textToBits,
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bitsToText
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) where
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import Data.Char (ord, chr)
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import Data.Bits (testBit)
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import qualified Data.Vector.Unboxed as VU
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createAlphabetFromText :: String -> [Char]
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createAlphabetFromText [] = []
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createAlphabetFromText (x:xs)
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| x `elem` alphabet = alphabet
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| otherwise = x : alphabet
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where
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alphabet = createAlphabetFromText xs
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indexOf :: (Eq t) => [t] -> t -> Int
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indexOf [] _ = -1
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indexOf (x : xs) target
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| x == target = 0
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| otherwise = 1 + indexOf xs target
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encryptCaesar :: [Char] -> Int -> String -> String
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encryptCaesar alphabet shift text = map caesarChar text
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where
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caesarChar c = alphabet !! ((indexOf alphabet c + shift) `mod` length alphabet)
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decryptCaesar :: [Char] -> Int -> String -> String
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decryptCaesar alphabet shift =
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encryptCaesar alphabet (alphabetLength - (shift `mod` alphabetLength))
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where
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alphabetLength = length alphabet
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textToBits :: String -> VU.Vector Int
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textToBits text = VU.fromList $ concatMap charToBits text
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where
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charToBits c = [if testBit (ord c) i then 1 else 0 | i <- [7,6..0]]
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bitsToText :: VU.Vector Int -> String
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bitsToText bits
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| VU.null bits = []
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| otherwise = (chr $ bitsToInt (VU.take 8 bits)) : bitsToText (VU.drop 8 bits)
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where
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bitsToInt charBits =
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sum [bit * (2 ^ index) | (bit, index) <- zip (VU.toList charBits) [7 :: Int,6..0]] |