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{-# LANGUAGE OverloadedStrings #-}
-- ASCIIArmor/Decode.hs: OpenPGP (RFC4880) ASCII armor implementation
-- Copyright Ⓒ 2012 Clint Adams
-- This software is released under the terms of the ISC license.
-- (See the LICENSE file).
module Codec.Encryption.OpenPGP.ASCIIArmor.Decode (
parseArmor
, decodeArmor
) where
import Codec.Encryption.OpenPGP.ASCIIArmor.Types
import Control.Applicative (many, (<|>), (<$>))
import Data.Attoparsec.ByteString (Parser, many1, string, inClass, notInClass, satisfy, word8, (<?>), parse, IResult(..))
import Data.Attoparsec.ByteString.Char8 (isDigit_w8)
import Data.Bits (shiftL)
import Data.ByteString (ByteString)
import qualified Data.ByteString as B
import qualified Data.ByteString.Char8 as BC8
import qualified Data.ByteString.Base64 as Base64
import Data.Digest.CRC24 (crc24)
import Data.Serialize (get)
import Data.Serialize.Get (Get, runGet, getWord8)
import Data.Serialize.Put (runPut, putWord32be)
import Data.String (IsString, fromString)
import Data.Word (Word32)
decodeArmor :: (Integral a, Read a, Show a, IsString e) => ByteString -> Either e (Armor a)
decodeArmor bs = case parse parseArmor bs of
Fail t c e -> Left (fromString e)
Partial _ -> Left (fromString "what")
Done _ r -> Right r
parseArmor :: (Integral a, Read a, Show a) => Parser (Armor a)
parseArmor = do
atype <- beginLine <?> "begin line"
headers <- armorHeaders <?> "headers"
blankishLine <?> "blank line"
payload <- base64Data <?> "base64 data"
endLine atype <?> "end line"
return $ Armor atype headers payload
beginLine :: (Integral a, Read a, Show a) => Parser (ArmorType a)
beginLine = do
string "-----BEGIN PGP "
atype <- message <|> pubkey <|> privkey<|> parts <|> signature
string "-----"
many (satisfy (inClass " \t"))
lineEnding
return atype
where
message = string "MESSAGE" >> return ArmorMessage
pubkey = string "PUBLIC KEY BLOCK" >> return ArmorPublicKeyBlock
privkey = string "PRIVATE KEY BLOCK" >> return ArmorPrivateKeyBlock
signature = string "SIGNATURE" >> return ArmorSignature
parts = do
string "MESSAGE, PART "
firstnum <- read . BC8.unpack . B.pack <$> many1 (satisfy isDigit_w8)
return $ ArmorSplitMessageIndefinite firstnum
lineEnding :: Parser ByteString
lineEnding = string "\n" <|> string "\r\n"
armorHeaders :: Parser [(String, String)]
armorHeaders = many armorHeader
armorHeader :: Parser (String, String)
armorHeader = do
key <- many1 (satisfy (inClass "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"))
string ": "
val <- many1 (satisfy (notInClass "\n\r"))
lineEnding
return (w8sToString key, w8sToString val)
where
w8sToString = BC8.unpack . B.pack
blankishLine :: Parser ByteString
blankishLine = many (satisfy (inClass " \t")) >> lineEnding
endLine :: (Integral a, Read a, Show a) => ArmorType a -> Parser ByteString
endLine atype = do
string $ "-----END PGP " `B.append` aType atype `B.append` "-----"
lineEnding
aType :: (Integral a, Read a, Show a) => ArmorType a -> ByteString
aType (ArmorMessage) = BC8.pack "MESSAGE"
aType (ArmorPublicKeyBlock) = BC8.pack "PUBLIC KEY BLOCK"
aType (ArmorPrivateKeyBlock) = BC8.pack "PRIVATE KEY BLOCK"
aType (ArmorSplitMessage x y) = BC8.pack $ "MESSAGE, PART " ++ show x ++ "/" ++ show y
aType (ArmorSplitMessageIndefinite x) = BC8.pack $ "MESSAGE, PART " ++ show x
aType (ArmorSignature) = BC8.pack "SIGNATURE"
base64Data :: Parser ByteString
base64Data = do
ls <- many1 base64Line
cksum <- checksumLine
let payload = B.concat ls
let ourcksum = crc24 payload
case runGet d24 cksum of
Left err -> fail err
Right theircksum -> if theircksum == ourcksum then return payload else fail ("CRC24 mismatch: " ++ show (B.unpack cksum) ++ "/" ++ show theircksum ++ " vs. " ++ show ourcksum)
where
base64Line :: Parser ByteString
base64Line = do
b64 <- many1 (satisfy (inClass "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"))
pad <- many (word8 (fromIntegral . fromEnum $ '='))
lineEnding
let line = B.pack b64 `B.append` B.pack pad
case Base64.decode line of
Left err -> fail err
Right bs -> return bs
checksumLine :: Parser ByteString
checksumLine = do
word8 (fromIntegral . fromEnum $ '=')
b64 <- many1 (satisfy (inClass "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"))
lineEnding
let line = B.pack b64
case Base64.decode line of
Left err -> fail err
Right bs -> return bs
d24 :: Get Word32
d24 = do
a <- getWord8
b <- getWord8
c <- getWord8
return $ shiftL (fromIntegral a :: Word32) 16 + shiftL (fromIntegral b :: Word32) 8 + (fromIntegral c :: Word32)
|
