From a901da5942b29e0a3f1ce358b6c14f56984934e7 Mon Sep 17 00:00:00 2001
From: Joe Crayne <joe@jerkface.net>
Date: Sat, 16 May 2020 08:17:38 -0400
Subject: Encode v5 signatures (draft-ietf-openpgp-rfc4880bis-09).

---
 Data/OpenPGP.hs | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/Data/OpenPGP.hs b/Data/OpenPGP.hs
index cc97cd6..dc6fb78 100644
--- a/Data/OpenPGP.hs
+++ b/Data/OpenPGP.hs
@@ -383,14 +383,14 @@ secret_key_fields alg  = fromMaybe (error $ "Unknown secret fields for "++show a
 -- Need this seperate for trailer calculation
 signature_packet_start :: Packet -> B.ByteString
 signature_packet_start (SignaturePacket {
-        version = 4,
+        version = v,
         signature_type = signature_type,
         key_algorithm = key_algorithm,
         hash_algorithm = hash_algorithm,
         hashed_subpackets = hashed_subpackets
-}) =
+}) | v==4 || v==5 =
         B.concat [
-                encode (0x04 :: Word8),
+                encode (v :: Word8),
                 encode signature_type,
                 encode key_algorithm,
                 encode hash_algorithm,
@@ -416,12 +416,16 @@ calculate_signature_trailer (SignaturePacket { version             = v,
         Just (SignatureCreationTimePacket creation_time) = find isCreation unhashed_subpackets
         isCreation (SignatureCreationTimePacket {}) = True
         isCreation _                                = False
-calculate_signature_trailer p@(SignaturePacket {version = 4}) =
+calculate_signature_trailer p@(SignaturePacket {version = v}) | v==4 || v==5 =
         B.concat [
                 signature_packet_start p,
-                encode (0x04 :: Word8),
+                -- TODO: v5 document signatures (type 0x00 or 0x01) hash more fields here.
+                encode (v :: Word8),
                 encode (0xff :: Word8),
-                encode (fromIntegral (B.length $ signature_packet_start p) :: Word32)
+                if v==4
+                    then encode (fromIntegral (B.length $ signature_packet_start p) :: Word32)
+                    else encode (fromIntegral (B.length $ signature_packet_start p) :: Word64)
+
         ]
 calculate_signature_trailer x =
         error ("Trying to calculate signature trailer for: " ++ show x)
@@ -544,21 +548,23 @@ put_packet (SignaturePacket { version             = v,
         Just (IssuerPacket keyidS) = find isIssuer unhashed_subpackets
         isIssuer (IssuerPacket {}) = True
         isIssuer _                 = False
-put_packet (SymmetricSessionKeyPacket version salgo s2k encd) =
-        (B.concat [encode version, encode salgo, encode s2k, encd], 3)
-put_packet (SignaturePacket { version             = 4,
+put_packet (SignaturePacket { version             = v,
                               unhashed_subpackets = unhashed_subpackets,
                               hash_head           = hash_head,
                               signature           = signature,
                               trailer             = trailer })           =
         (B.concat $ [
-                trailer_top,
+                B.take n trailer,
                 encode (fromIntegral $ B.length unhashed :: Word16),
                 unhashed, encode hash_head
         ] ++ map encode signature, 2)
         where
-        trailer_top = B.reverse $ B.drop 6 $ B.reverse trailer
+        n = case B.length trailer - (if v==5 then 10 else 6) of
+                x | x >=0     -> x
+                  | otherwise -> 0 -- Should never happen.
         unhashed = B.concat $ map encode unhashed_subpackets
+put_packet (SymmetricSessionKeyPacket version salgo s2k encd) =
+        (B.concat [encode version, encode salgo, encode s2k, encd], 3)
 put_packet (OnePassSignaturePacket { version = version,
                                      signature_type = signature_type,
                                      hash_algorithm = hash_algorithm,
-- 
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