{-# LINE 1 "OpenSSL/DSA.hsc" #-}
{- -*- haskell -*- -}
{-# LINE 2 "OpenSSL/DSA.hsc" #-}

{-# OPTIONS_HADDOCK prune #-}

-- | The Digital Signature Algorithm (FIPS 186-2).
--   See <http://www.openssl.org/docs/crypto/dsa.html>


{-# LINE 9 "OpenSSL/DSA.hsc" #-}

module OpenSSL.DSA
    ( -- * Type
      DSAKey(..)
    , DSAPubKey
    , DSAKeyPair
    , DSA -- private

      -- * Key and parameter generation
    , generateDSAParameters
    , generateDSAKey
    , generateDSAParametersAndKey

      -- * Signing and verification
    , signDigestedDataWithDSA
    , verifyDigestedDataWithDSA

      -- * Extracting fields of DSA objects
    , dsaPrivate
    , dsaPubKeyToTuple
    , dsaKeyPairToTuple
    , tupleToDSAPubKey
    , tupleToDSAKeyPair
    ) where

import           Control.Monad
import qualified Data.ByteString as BS
import           Data.Typeable
import           Foreign
import           Foreign.C (CString)
import           Foreign.C.Types
import           OpenSSL.BN
import           OpenSSL.Utils

{-# LINE 45 "OpenSSL/DSA.hsc" #-}

-- | The type of a DSA public key, includes parameters p, q, g and public.
newtype DSAPubKey = DSAPubKey (ForeignPtr DSA)
    deriving Typeable

-- | The type of a DSA keypair, includes parameters p, q, g, public and private.
newtype DSAKeyPair = DSAKeyPair (ForeignPtr DSA)
    deriving Typeable

-- DSAPubKey and DSAKeyPair are in fact the same type at the OpenSSL
-- level, but we want to treat them differently for type-safety.
data DSA

-- |@'DSAKey' a@ is either 'DSAPubKey' or 'DSAKeyPair'.
class DSAKey k where
    -- |Return the length of key.
    dsaSize :: k -> Int
    dsaSize dsa
        = unsafePerformIO $
          withDSAPtr dsa $ \ dsaPtr ->
              _size dsaPtr >>= return . fromIntegral

    -- |Return the public prime number of the key.
    dsaP :: k -> Integer
    dsaP = peekI ((\hsc_ptr -> peekByteOff hsc_ptr 12))
{-# LINE 70 "OpenSSL/DSA.hsc" #-}

    -- |Return the public 160-bit subprime, @q | p - 1@ of the key.
    dsaQ :: k -> Integer
    dsaQ = peekI ((\hsc_ptr -> peekByteOff hsc_ptr 16))
{-# LINE 74 "OpenSSL/DSA.hsc" #-}

    -- |Return the public generator of subgroup of the key.
    dsaG :: k -> Integer
    dsaG = peekI ((\hsc_ptr -> peekByteOff hsc_ptr 20))
{-# LINE 78 "OpenSSL/DSA.hsc" #-}

    -- |Return the public key @y = g^x@.
    dsaPublic :: k -> Integer
    dsaPublic = peekI ((\hsc_ptr -> peekByteOff hsc_ptr 24))
{-# LINE 82 "OpenSSL/DSA.hsc" #-}

    -- private
    withDSAPtr   :: k -> (Ptr DSA -> IO a) -> IO a
    peekDSAPtr   :: Ptr DSA -> IO (Maybe k)
    absorbDSAPtr :: Ptr DSA -> IO (Maybe k)


instance DSAKey DSAPubKey where
    withDSAPtr (DSAPubKey fp) = withForeignPtr fp
    peekDSAPtr dsaPtr         = _pubDup dsaPtr >>= absorbDSAPtr
    absorbDSAPtr dsaPtr       = newForeignPtr _free dsaPtr >>= return . Just . DSAPubKey


instance DSAKey DSAKeyPair where
    withDSAPtr (DSAKeyPair fp) = withForeignPtr fp
    peekDSAPtr dsaPtr
        = do hasP <- hasDSAPrivateKey dsaPtr
             if hasP then
                 _privDup dsaPtr >>= absorbDSAPtr
               else
                 return Nothing
    absorbDSAPtr dsaPtr
        = do hasP <- hasDSAPrivateKey dsaPtr
             if hasP then
                 newForeignPtr _free dsaPtr >>= return . Just . DSAKeyPair
               else
                 return Nothing


hasDSAPrivateKey :: Ptr DSA -> IO Bool
hasDSAPrivateKey dsaPtr
    = ((\hsc_ptr -> peekByteOff hsc_ptr 28)) dsaPtr >>= return . (/= nullPtr)
{-# LINE 114 "OpenSSL/DSA.hsc" #-}


foreign import ccall unsafe "&DSA_free"
        _free :: FunPtr (Ptr DSA -> IO ())

foreign import ccall unsafe "DSA_free"
        dsa_free :: Ptr DSA -> IO ()

foreign import ccall unsafe "BN_free"
        _bn_free :: Ptr BIGNUM -> IO ()

foreign import ccall unsafe "DSA_new"
        _dsa_new :: IO (Ptr DSA)

foreign import ccall unsafe "DSA_generate_key"
        _dsa_generate_key :: Ptr DSA -> IO ()

foreign import ccall unsafe "HsOpenSSL_dsa_sign"
        _dsa_sign :: Ptr DSA -> CString -> CInt -> Ptr (Ptr BIGNUM) -> Ptr (Ptr BIGNUM) -> IO CInt

foreign import ccall unsafe "HsOpenSSL_dsa_verify"
        _dsa_verify :: Ptr DSA -> CString -> CInt -> Ptr BIGNUM -> Ptr BIGNUM -> IO CInt

foreign import ccall safe "DSA_generate_parameters"
        _generate_params :: CInt -> Ptr CChar -> CInt -> Ptr CInt -> Ptr CInt -> Ptr () -> Ptr () -> IO (Ptr DSA)

foreign import ccall unsafe "HsOpenSSL_DSAPublicKey_dup"
        _pubDup :: Ptr DSA -> IO (Ptr DSA)

foreign import ccall unsafe "HsOpenSSL_DSAPrivateKey_dup"
        _privDup :: Ptr DSA -> IO (Ptr DSA)

foreign import ccall unsafe "DSA_size"
        _size :: Ptr DSA -> IO CInt

peekI :: DSAKey k => (Ptr DSA -> IO (Ptr BIGNUM)) -> k -> Integer
peekI peeker dsa
    = unsafePerformIO $
      withDSAPtr dsa $ \ dsaPtr ->
          do bn <- peeker dsaPtr
             when (bn == nullPtr) $ fail "peekI: got a nullPtr"
             peekBN (wrapBN bn)

-- | Generate DSA parameters (*not* a key, but required for a key). This is a
--   compute intensive operation. See FIPS 186-2, app 2. This agrees with the
--   test vectors given in FIP 186-2, app 5
generateDSAParameters :: Int  -- ^ The number of bits in the generated prime: 512 <= x <= 1024
                      -> Maybe BS.ByteString  -- ^ optional seed, its length must be 20 bytes
                      -> IO (Int, Int, Integer, Integer, Integer)  -- ^ (iteration count, generator count, p, q, g)
generateDSAParameters nbits mseed = do
  when (nbits < 512 || nbits > 1024) $ fail "Invalid DSA bit size"
  alloca (\i1 -> do
    alloca (\i2 -> do
      (\x -> case mseed of
                  Nothing -> x (nullPtr, 0)
                  Just seed -> BS.useAsCStringLen seed x) (\(seedptr, seedlen) -> do
        ptr <- _generate_params (fromIntegral nbits) seedptr (fromIntegral seedlen) i1 i2 nullPtr nullPtr
        failIfNull_ ptr
        itcount <- peek i1
        gencount <- peek i2
        p <- ((\hsc_ptr -> peekByteOff hsc_ptr 12)) ptr >>= peekBN . wrapBN
{-# LINE 175 "OpenSSL/DSA.hsc" #-}
        q <- ((\hsc_ptr -> peekByteOff hsc_ptr 16)) ptr >>= peekBN . wrapBN
{-# LINE 176 "OpenSSL/DSA.hsc" #-}
        g <- ((\hsc_ptr -> peekByteOff hsc_ptr 20)) ptr >>= peekBN . wrapBN
{-# LINE 177 "OpenSSL/DSA.hsc" #-}
        dsa_free ptr
        return (fromIntegral itcount, fromIntegral gencount, p, q, g))))

{-
-- | This function just runs the example DSA generation, as given in FIP 186-2,
--   app 5. The return values should be:
--   (105,
--    "8df2a494492276aa3d25759bb06869cbeac0d83afb8d0cf7cbb8324f0d7882e5d0762fc5b7210
--     eafc2e9adac32ab7aac49693dfbf83724c2ec0736ee31c80291",
--     "c773218c737ec8ee993b4f2ded30f48edace915f",
--     "626d027839ea0a13413163a55b4cb500299d5522956cefcb3bff10f399ce2c2e71cb9de5fa24
--      babf58e5b79521925c9cc42e9f6f464b088cc572af53e6d78802"), as given at the bottom of
--    page 21
test_generateParameters = do
  let seed = BS.pack [0xd5, 0x01, 0x4e, 0x4b,
                      0x60, 0xef, 0x2b, 0xa8,
                      0xb6, 0x21, 0x1b, 0x40,
                      0x62, 0xba, 0x32, 0x24,
                      0xe0, 0x42, 0x7d, 0xd3]
  (a, b, p, q, g) <- generateParameters 512 $ Just seed
  return (a, toHex p, toHex q, g)
-}

-- | Generate a new DSA keypair, given valid parameters
generateDSAKey :: Integer  -- ^ p
               -> Integer  -- ^ q
               -> Integer  -- ^ g
               -> IO DSAKeyPair
generateDSAKey p q g = do
  ptr <- _dsa_new
  newBN p >>= return . unwrapBN >>= ((\hsc_ptr -> pokeByteOff hsc_ptr 12)) ptr
{-# LINE 208 "OpenSSL/DSA.hsc" #-}
  newBN q >>= return . unwrapBN >>= ((\hsc_ptr -> pokeByteOff hsc_ptr 16)) ptr
{-# LINE 209 "OpenSSL/DSA.hsc" #-}
  newBN g >>= return . unwrapBN >>= ((\hsc_ptr -> pokeByteOff hsc_ptr 20)) ptr
{-# LINE 210 "OpenSSL/DSA.hsc" #-}
  _dsa_generate_key ptr
  newForeignPtr _free ptr >>= return . DSAKeyPair

-- |Return the private key @x@.
dsaPrivate :: DSAKeyPair -> Integer
dsaPrivate = peekI ((\hsc_ptr -> peekByteOff hsc_ptr 28))
{-# LINE 216 "OpenSSL/DSA.hsc" #-}

-- | Convert a DSAPubKey object to a tuple of its members in the
--   order p, q, g, and public.
dsaPubKeyToTuple :: DSAKeyPair -> (Integer, Integer, Integer, Integer)
dsaPubKeyToTuple dsa
    = let p   = peekI ((\hsc_ptr -> peekByteOff hsc_ptr 12)) dsa
{-# LINE 222 "OpenSSL/DSA.hsc" #-}
          q   = peekI ((\hsc_ptr -> peekByteOff hsc_ptr 16)) dsa
{-# LINE 223 "OpenSSL/DSA.hsc" #-}
          g   = peekI ((\hsc_ptr -> peekByteOff hsc_ptr 20)) dsa
{-# LINE 224 "OpenSSL/DSA.hsc" #-}
          pub = peekI ((\hsc_ptr -> peekByteOff hsc_ptr 24)) dsa
{-# LINE 225 "OpenSSL/DSA.hsc" #-}
      in
        (p, q, g, pub)

-- | Convert a DSAKeyPair object to a tuple of its members in the
--   order p, q, g, public and private.
dsaKeyPairToTuple :: DSAKeyPair -> (Integer, Integer, Integer, Integer, Integer)
dsaKeyPairToTuple dsa
    = let p   = peekI ((\hsc_ptr -> peekByteOff hsc_ptr 12)) dsa
{-# LINE 233 "OpenSSL/DSA.hsc" #-}
          q   = peekI ((\hsc_ptr -> peekByteOff hsc_ptr 16)) dsa
{-# LINE 234 "OpenSSL/DSA.hsc" #-}
          g   = peekI ((\hsc_ptr -> peekByteOff hsc_ptr 20)) dsa
{-# LINE 235 "OpenSSL/DSA.hsc" #-}
          pub = peekI ((\hsc_ptr -> peekByteOff hsc_ptr 24)) dsa
{-# LINE 236 "OpenSSL/DSA.hsc" #-}
          pri = peekI ((\hsc_ptr -> peekByteOff hsc_ptr 28)) dsa
{-# LINE 237 "OpenSSL/DSA.hsc" #-}
      in
        (p, q, g, pub, pri)

-- | Convert a tuple of members (in the same format as from
--   'dsaPubKeyToTuple') into a DSAPubKey object
tupleToDSAPubKey :: (Integer, Integer, Integer, Integer) -> DSAPubKey
tupleToDSAPubKey (p, q, g, pub) = unsafePerformIO $ do
  ptr <- _dsa_new
  newBN p   >>= return . unwrapBN >>= ((\hsc_ptr -> pokeByteOff hsc_ptr 12)) ptr
{-# LINE 246 "OpenSSL/DSA.hsc" #-}
  newBN q   >>= return . unwrapBN >>= ((\hsc_ptr -> pokeByteOff hsc_ptr 16)) ptr
{-# LINE 247 "OpenSSL/DSA.hsc" #-}
  newBN g   >>= return . unwrapBN >>= ((\hsc_ptr -> pokeByteOff hsc_ptr 20)) ptr
{-# LINE 248 "OpenSSL/DSA.hsc" #-}
  newBN pub >>= return . unwrapBN >>= ((\hsc_ptr -> pokeByteOff hsc_ptr 24)) ptr
{-# LINE 249 "OpenSSL/DSA.hsc" #-}
  ((\hsc_ptr -> pokeByteOff hsc_ptr 28)) ptr nullPtr
{-# LINE 250 "OpenSSL/DSA.hsc" #-}
  newForeignPtr _free ptr >>= return . DSAPubKey

-- | Convert a tuple of members (in the same format as from
--   'dsaPubKeyToTuple') into a DSAPubKey object
tupleToDSAKeyPair :: (Integer, Integer, Integer, Integer, Integer) -> DSAKeyPair
tupleToDSAKeyPair (p, q, g, pub, pri) = unsafePerformIO $ do
  ptr <- _dsa_new
  newBN p   >>= return . unwrapBN >>= ((\hsc_ptr -> pokeByteOff hsc_ptr 12)) ptr
{-# LINE 258 "OpenSSL/DSA.hsc" #-}
  newBN q   >>= return . unwrapBN >>= ((\hsc_ptr -> pokeByteOff hsc_ptr 16)) ptr
{-# LINE 259 "OpenSSL/DSA.hsc" #-}
  newBN g   >>= return . unwrapBN >>= ((\hsc_ptr -> pokeByteOff hsc_ptr 20)) ptr
{-# LINE 260 "OpenSSL/DSA.hsc" #-}
  newBN pub >>= return . unwrapBN >>= ((\hsc_ptr -> pokeByteOff hsc_ptr 24)) ptr
{-# LINE 261 "OpenSSL/DSA.hsc" #-}
  newBN pri >>= return . unwrapBN >>= ((\hsc_ptr -> pokeByteOff hsc_ptr 28)) ptr
{-# LINE 262 "OpenSSL/DSA.hsc" #-}
  newForeignPtr _free ptr >>= return . DSAKeyPair

-- | A utility function to generate both the parameters and the key pair at the
--   same time. Saves serialising and deserialising the parameters too
generateDSAParametersAndKey :: Int  -- ^ The number of bits in the generated prime: 512 <= x <= 1024
                            -> Maybe BS.ByteString  -- ^ optional seed, its length must be 20 bytes
                            -> IO DSAKeyPair
generateDSAParametersAndKey nbits mseed = do
  (\x -> case mseed of
              Nothing -> x (nullPtr, 0)
              Just seed -> BS.useAsCStringLen seed x) (\(seedptr, seedlen) -> do
    ptr <- _generate_params (fromIntegral nbits) seedptr (fromIntegral seedlen) nullPtr nullPtr nullPtr nullPtr
    failIfNull_ ptr
    _dsa_generate_key ptr
    newForeignPtr _free ptr >>= return . DSAKeyPair)

-- | Sign pre-digested data. The DSA specs call for SHA1 to be used so, if you
--   use anything else, YMMV. Returns a pair of Integers which, together, are
--   the signature
signDigestedDataWithDSA :: DSAKeyPair -> BS.ByteString -> IO (Integer, Integer)
signDigestedDataWithDSA dsa bytes = do
  BS.useAsCStringLen bytes (\(ptr, len) -> do
    alloca (\rptr -> do
      alloca (\sptr -> do
        withDSAPtr dsa (\dsaptr -> do
          _dsa_sign dsaptr ptr (fromIntegral len) rptr sptr >>= failIf_ (== 0)
          r <- peek rptr >>= peekBN . wrapBN
          peek rptr >>= _bn_free
          s <- peek sptr >>= peekBN . wrapBN
          peek sptr >>= _bn_free
          return (r, s)))))

-- | Verify pre-digested data given a signature.
verifyDigestedDataWithDSA :: DSAKey k => k -> BS.ByteString -> (Integer, Integer) -> IO Bool
verifyDigestedDataWithDSA dsa bytes (r, s) = do
  BS.useAsCStringLen bytes (\(ptr, len) -> do
    withBN r (\bnR -> do
      withBN s (\bnS -> do
        withDSAPtr dsa (\dsaptr -> do
          _dsa_verify dsaptr ptr (fromIntegral len) (unwrapBN bnR) (unwrapBN bnS) >>= return . (== 1)))))


instance Eq DSAPubKey where
    a == b
        = dsaP      a == dsaP      b &&
          dsaQ      a == dsaQ      b &&
          dsaG      a == dsaG      b &&
          dsaPublic a == dsaPublic b

instance Eq DSAKeyPair where
    a == b
        = dsaP       a == dsaP       b &&
          dsaQ       a == dsaQ       b &&
          dsaG       a == dsaG       b &&
          dsaPublic  a == dsaPublic  b &&
          dsaPrivate a == dsaPrivate b

instance Ord DSAPubKey where
    a `compare` b
        | dsaP      a < dsaP      b = LT
        | dsaP      a > dsaP      b = GT
        | dsaQ      a < dsaQ      b = LT
        | dsaQ      a > dsaQ      b = GT
        | dsaG      a < dsaG      b = LT
        | dsaG      a > dsaG      b = GT
        | dsaPublic a < dsaPublic b = LT
        | dsaPublic a > dsaPublic b = GT
        | otherwise                 = EQ

instance Ord DSAKeyPair where
    a `compare` b
        | dsaP       a < dsaP       b = LT
        | dsaP       a > dsaP       b = GT
        | dsaQ       a < dsaQ       b = LT
        | dsaQ       a > dsaQ       b = GT
        | dsaG       a < dsaG       b = LT
        | dsaG       a > dsaG       b = GT
        | dsaPublic  a < dsaPublic  b = LT
        | dsaPublic  a > dsaPublic  b = GT
        | dsaPrivate a < dsaPrivate b = LT
        | dsaPrivate a > dsaPrivate b = GT
        | otherwise                   = EQ

instance Show DSAPubKey where
    show a
        = concat [ "DSAPubKey {"
                 , "dsaP = ", show (dsaP a), ", "
                 , "dsaQ = ", show (dsaQ a), ", "
                 , "dsaG = ", show (dsaG a), ", "
                 , "dsaPublic = ", show (dsaPublic a)
                 , "}"
                 ]

instance Show DSAKeyPair where
    show a
        = concat [ "DSAPubKey {"
                 , "dsaP = ", show (dsaP a), ", "
                 , "dsaQ = ", show (dsaQ a), ", "
                 , "dsaG = ", show (dsaG a), ", "
                 , "dsaPublic = ", show (dsaPublic a), ", "
                 , "dsaPrivate = ", show (dsaPrivate a)
                 , "}"
                 ]