From 6318898455d3ac20e7e44d0a080d43f8c3ff120b Mon Sep 17 00:00:00 2001
From: Reinaldo de Souza Jr <juniorz@gmail.com>
Date: Mon, 29 Aug 2016 11:24:29 -0500
Subject: [PATCH] crypto/openpgp: return error from userIdSignatureHash

Signature#SignUserId was ignoring the error returned by userIdSignatureHash.
This error can happen, for example, when the Signature's Hash property is
uninitialized. Not returning the error makes it hard for the user to detect
the problem.

Change-Id: I0ae0033e77bfb1ea1c06b0769f949e48c713adc6
Reviewed-on: https://go-review.googlesource.com/27997
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
---
 openpgp/packet/signature.go      |  2 +-
 openpgp/packet/signature_test.go | 36 ++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/openpgp/packet/signature.go b/openpgp/packet/signature.go
index 4368f6b..3fc66db 100644
--- a/openpgp/packet/signature.go
+++ b/openpgp/packet/signature.go
@@ -553,7 +553,7 @@ func (sig *Signature) Sign(h hash.Hash, priv *PrivateKey, config *Config) (err e
 func (sig *Signature) SignUserId(id string, pub *PublicKey, priv *PrivateKey, config *Config) error {
 	h, err := userIdSignatureHash(id, pub, sig.Hash)
 	if err != nil {
-		return nil
+		return err
 	}
 	return sig.Sign(h, priv, config)
 }
diff --git a/openpgp/packet/signature_test.go b/openpgp/packet/signature_test.go
index c1bbde8..56e7611 100644
--- a/openpgp/packet/signature_test.go
+++ b/openpgp/packet/signature_test.go
@@ -39,4 +39,40 @@ func TestSignatureReserialize(t *testing.T) {
 	}
 }
 
+func TestSignUserId(t *testing.T) {
+	sig := &Signature{
+		SigType:    SigTypeGenericCert,
+		PubKeyAlgo: PubKeyAlgoRSA,
+		Hash:       0, // invalid hash function
+	}
+
+	packet, err := Read(readerFromHex(rsaPkDataHex))
+	if err != nil {
+		t.Fatalf("failed to deserialize public key: %v", err)
+	}
+	pubKey := packet.(*PublicKey)
+
+	packet, err = Read(readerFromHex(privKeyRSAHex))
+	if err != nil {
+		t.Fatalf("failed to deserialize private key: %v", err)
+	}
+	privKey := packet.(*PrivateKey)
+
+	err = sig.SignUserId("", pubKey, privKey, nil)
+	if err == nil {
+		t.Errorf("did not receive an error when expected")
+	}
+
+	sig.Hash = crypto.SHA256
+	err = privKey.Decrypt([]byte("testing"))
+	if err != nil {
+		t.Fatalf("failed to decrypt private key: %v", err)
+	}
+
+	err = sig.SignUserId("", pubKey, privKey, nil)
+	if err != nil {
+		t.Errorf("failed to sign user id: %v", err)
+	}
+}
+
 const signatureDataHex = "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"