1 files changed, 51 insertions, 0 deletions

diff --git a/Data/OpenPGP/Util/Ed25519.hs b/Data/OpenPGP/Util/Ed25519.hs
new file mode 100644
index 0000000..ed277c8
--- /dev/null
+++ b/Data/OpenPGP/Util/Ed25519.hs
@@ -0,0 +1,51 @@
+module Data.OpenPGP.Util.Ed25519 where
+
+import Crypto.Error
+import qualified Crypto.PubKey.Ed25519 as Ed25519
+import Data.OpenPGP.Internal -- (integerToBS,integerToLE,getBigNumLE)
+import qualified Data.OpenPGP as OpenPGP
+import Crypto.ECC.Edwards25519
+
+import qualified Data.ByteArray as BA
+import Control.Monad
+import qualified Data.ByteString as BS
+import qualified Data.ByteString.Lazy as BL
+import Data.List
+import Data.Int
+import Data.Word
+import Data.OpenPGP.Util.Base
+
+import Text.Printf
+import Numeric
+import Data.Char
+import System.IO
+
+import Foreign.Ptr
+import System.IO.Unsafe
+
+import Crypto.Cipher.SBox
+
+ed25519Key :: OpenPGP.Packet -> Maybe Ed25519.PublicKey
+ed25519Key k = case Ed25519.publicKey $ integerToBS $ keyParam 'n' k of
+    CryptoPassed ed25519 -> Just ed25519
+    CryptoFailed err     -> Nothing
+
+ed25519sig sig =
+    let [OpenPGP.MPI r,OpenPGP.MPI s] = OpenPGP.signature sig
+        -- rbs = BS.pack $ take 32 $ rbytes r ++ repeat 0
+        -- sbs = BS.pack $ take 32 $ rbytes s ++ repeat 0
+        rbs = let r' = integerToBS r in BS.replicate (32 - BS.length r') 0 <> r'
+        sbs = let s' = integerToBS s in BS.replicate (32 - BS.length s') 0 <> s'
+    in case Ed25519.signature (rbs <> sbs) of
+        CryptoPassed sig -> Just sig
+        CryptoFailed err -> Nothing
+
+ed25519Verify :: OpenPGP.Packet -> BS.ByteString -> OpenPGP.Packet -> Maybe Bool
+ed25519Verify sig over k = do
+    let hashbs = hashBySymbol (OpenPGP.hash_algorithm sig) $ BL.fromChunks [over]
+    guard $ 0x2B06010401DA470F01 == keyParam 'c' k -- Only Ed25519 curve.
+    k' <- ed25519Key k -- SecretKeyPacket ???
+    sig' <- ed25519sig sig
+    let result = Ed25519.verify k' hashbs sig'
+    Just result
+