diff options
Diffstat (limited to 'base64/base64.hs')
| -rw-r--r-- | base64/base64.hs | 80 |
1 files changed, 41 insertions, 39 deletions
diff --git a/base64/base64.hs b/base64/base64.hs index 13f12bb..2443d07 100644 --- a/base64/base64.hs +++ b/base64/base64.hs @@ -1,45 +1,47 @@ --- --- Miguel's Naive --- Base64 Encoder -- Coded on a winter afterfnoon on 19th Feb 2018 A.D. --- to fully understand base64 encoding and play with --- haskell, which is always an indisputable pleasure. --- --- The following lines were written in full awareness --- that 'libraries' for this purpose, which perform way --- better, are in existence. --- --- Coded in big anger due to nick's stories about saving his binary --- format, encrypted passwords in an ascii config file, featuring --- strange letters and characters. --- --- Example Usage: echo "just testing" | stack runghc base64.hs | stack runghc base64 -- -d --- (You can cross check with base64 / base64 -d) - -import System.Environment -import qualified Data.List.Split as T -import qualified Data.List as L -import qualified Data.Map.Strict as M +import Data.Maybe (fromJust,isJust) +import Data.List.Split (chunksOf) +import Data.Tuple (swap) +import Data.Tuple.Extra (first,second,dupe) +import System.Environment (getArgs) import qualified Data.ByteString.Lazy as B -import Text.Printf -import Data.Maybe -import Data.Char -import Control.Monad +import qualified Data.ByteString.Lazy.Char8 as C +import qualified Data.Map as M -main = do args<-getArgs - if length args == 0 then go encode64 - else when (args!!0 == "-d") $ go decode64 - where go f = getContents >>= putStr.(++"\n").f +-- Example Usage: echo "hello world" | ./base64 | ./base64 -d -fromBase64 x = (['A'..'Z']++['a'..'z']++['0'..'9']++['+','/']) !! x -mapBase64 = M.fromList $ map (\x-> (fromBase64 x,x)) [0..63] -binToDec = sum . map (2^) . L.findIndices (=='1') . reverse +-- TODO +-- cleanup/simplify +-- unit testing (cross check with cli base64, different lengths) +-- flag for line widht / check flags / filename on command-line +-- (see man base64) +-- compare performance . named map? array? -encode64 x = pad64 (length x) . map (fromBase64 . binToDec) . T.chunksOf 6 . - concat . map (printf "%08b" ) $ x ++ cycle "\000" +main = do arg<-getArgs + dat<-B.getContents + B.putStr.B.pack.encode.B.unpack $ dat +{- + if length arg == 0 + then putStr . (++"\n") . encode64 . map fromIntegral . B.unpack $ dat + else B.putStr. B.pack . map fromIntegral . decode64 . C.unpack $ dat +-} -decode64 x = map (chr . binToDec) . T.chunksOf 8 . - concat . map ( printf "%06b" . fromJust) . filter isJust . - map (flip M.lookup mapBase64) $ x +encode = map ((+65).(`mod` 24)) -pad64 l = (++(take m ((cycle "=")))) . take ((l+m)*3 `div` 2 -3-m) - where m = mod (3 - mod l 3) 3 +table64 = zip [0..] (['A'..'Z']++['a'..'z']++['0'..'9']++['+','/']) + +enc64 k = M.lookup k mp where mp = M.fromList table64 +dec64 k = M.lookup k mp where mp = M.fromList $ map swap table64 + +encode64 :: [Int] -> [Char] +encode64 = map (fromJust.enc64.flip mod 64) -- concat . map (pad . first enc . second length . dupe) . chunksOf 3 + where enc = map (fromJust . enc64) . sumC + pad (v,l) =take 4 $ take (1+l) v ++ "===" + sumC = map fst . reverse . take 4 . drop 1 .iterate to64 . (,) 0 . sum . map (uncurry (*)) . zip mult + mult = map (256^) [2,1,0] + to64 (r,v) = let r' = v `mod` 64 in (r',(v-r')`div`64) + +decode64 :: [Char]->[Int] +decode64 = map fst . concat . map (rem . first (reverse . take 3 . drop 1 . iterate to256 . (,) 0 . dec. map (fromJust) . filter (isJust) . map dec64).second (length.filter(=='=')). dupe) . chunksOf 4 . filter (/='\n') + where dec = sum . map (uncurry (*)) . zip (map (64^) [3,2..]) + to256 (r,v) = let r' = v `mod` 256 in (r',(v-r')`div`256) + rem (v,l) = take (3-l) v |