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module DNSKey where
import Data.Binary
import Data.Binary.Get
import Data.Binary.Put
import Data.Bits
import qualified Data.ByteString as B
import qualified Data.ByteString.Lazy as L
import Data.Word
-- RSA n e
-- n = modulus
-- e = exponent
data RSA = RSA Integer Integer
deriving (Eq,Show)
getRSA len = do
elen <- do
tog <- get
case tog :: Word8 of
0 -> get :: Get Word16
_ -> return $ fromIntegral tog
ebs <- getByteString (fromIntegral elen)
nlen <- fmap (fromIntegral . ((-) len)) bytesRead
nbs <- getByteString nlen
let e = snd $ B.foldl' (\(c,a) w8 -> (c-1, a + 256^c * fromIntegral w8)) (elen-1,0) ebs
n = snd $ B.foldl' (\(c,a) w8 -> (c-1, a + 256^c * fromIntegral w8)) (nlen-1,0) nbs
return $ RSA n e
putRSA (RSA n e) = do
if elen > 255 || elen==0
then do
put (0 :: Word8)
put (fromIntegral elen :: Word16)
else do
put (fromIntegral elen :: Word8)
putByteString ebs
putByteString nbs
where
elen = B.length ebs
ebs = i2bs_unsized e
nbs = i2bs_unsized n
-- |@i2bs_unsized i@ converts @i@ to a 'ByteString' of sufficient bytes to express the integer.
-- The integer must be non-negative and a zero will be encoded in one byte.
--
-- Thanks: Thomas DuBuisson (crypto-api)
i2bs_unsized :: Integer -> B.ByteString
i2bs_unsized 0 = B.singleton 0
i2bs_unsized i = B.reverse $ B.unfoldr (\i' -> if i' <= 0 then Nothing else Just (fromIntegral i', (i' `shiftR` 8))) i
{-# INLINE i2bs_unsized #-}
{-
main = do
bs <- L.getContents
let rsa = runGet (getRSA (fromIntegral $ L.length bs)) bs
bs' = runPut (putRSA rsa)
rsa' = runGet (getRSA (fromIntegral $ L.length bs)) bs'
print rsa
print rsa'
-}
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