From 7fd793dc5e6ca5623b6c32e786a39cd6293661b1 Mon Sep 17 00:00:00 2001
From: marin thiercelin <marin.thiercelin@protonmail.com>
Date: Mon, 20 Dec 2021 12:36:52 +0100
Subject: [PATCH] Only verify and get the time stamp of the first signature
 packet

If the detached signature has several packets,
GetVerifiedSignatureTimestamp() only verifies and returns
the timestamp of the first packet
---
 crypto/keyring_message.go | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/crypto/keyring_message.go b/crypto/keyring_message.go
index 6bb92303..c2254878 100644
--- a/crypto/keyring_message.go
+++ b/crypto/keyring_message.go
@@ -122,11 +122,30 @@ func (keyRing *KeyRing) VerifyDetachedEncrypted(message *PlainMessage, encrypted
 // returns the creation time of the signature if it succeeds
 // and returns a SignatureVerificationError if fails.
 func (keyRing *KeyRing) GetVerifiedSignatureTimestamp(message *PlainMessage, signature *PGPSignature, verifyTime int64) (int64, error) {
-	err := keyRing.VerifyDetached(message, signature, verifyTime)
+	packets := packet.NewReader(bytes.NewReader(signature.Data))
+	p, err := packets.Next()
+	if err != nil {
+		return 0, errors.Wrap(err, "gopenpgp: can't parse signature")
+	}
+	sigPacket, ok := p.(*packet.Signature)
+	if !ok {
+		return 0, errors.New("gopenpgp: non signature packet found")
+	}
+	var outBuf bytes.Buffer
+	err = sigPacket.Serialize(&outBuf)
+	if err != nil {
+		return 0, errors.Wrap(err, "gopenpgp: can't serialize signature packet")
+	}
+	err = verifySignature(
+		keyRing.entities,
+		message.NewReader(),
+		outBuf.Bytes(),
+		verifyTime,
+	)
 	if err != nil {
 		return 0, err
 	}
-	return signature.getCreationTime()
+	return sigPacket.CreationTime.Unix(), nil
 }
 
 // ------ INTERNAL FUNCTIONS -------