Fix missing 0 prefix of GPG key id (#30245)

Fixes #30235

If the key id "front" byte has a single digit, `%X` is missing the 0
prefix.
` 38D1A3EADDBEA9C` instead of
`038D1A3EADDBEA9C`
When using the `IssuerFingerprint` slice `%X` is enough but I changed it
to `%016X` too to be consistent.

models/asymkey/gpg_key_commit_verification.go

@@ -139,13 +139,7 @@ func ParseCommitWithSignature(ctx context.Context, c *git.Commit) *CommitVerific
 		}
 	}
 
-	keyID := ""
-	if sig.IssuerKeyId != nil && (*sig.IssuerKeyId) != 0 {
-		keyID = fmt.Sprintf("%X", *sig.IssuerKeyId)
-	}
-	if keyID == "" && sig.IssuerFingerprint != nil && len(sig.IssuerFingerprint) > 0 {
-		keyID = fmt.Sprintf("%X", sig.IssuerFingerprint[12:20])
-	}
+	keyID := tryGetKeyIDFromSignature(sig)
 	defaultReason := NoKeyFound
 
 	// First check if the sig has a keyID and if so just look at that

models/asymkey/gpg_key_common.go

@@ -134,3 +134,13 @@ func extractSignature(s string) (*packet.Signature, error) {
 	}
 	return sig, nil
 }
+
+func tryGetKeyIDFromSignature(sig *packet.Signature) string {
+	if sig.IssuerKeyId != nil && (*sig.IssuerKeyId) != 0 {
+		return fmt.Sprintf("%016X", *sig.IssuerKeyId)
+	}
+	if sig.IssuerFingerprint != nil && len(sig.IssuerFingerprint) > 0 {
+		return fmt.Sprintf("%016X", sig.IssuerFingerprint[12:20])
+	}
+	return ""
+}

models/asymkey/gpg_key_test.go

@@ -11,7 +11,9 @@ import (
 	"code.gitea.io/gitea/models/unittest"
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/timeutil"
+	"code.gitea.io/gitea/modules/util"
 
+	"github.com/keybase/go-crypto/openpgp/packet"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -391,3 +393,13 @@ epiDVQ==
 		assert.Equal(t, time.Unix(1586105389, 0), expire)
 	}
 }
+
+func TestTryGetKeyIDFromSignature(t *testing.T) {
+	assert.Empty(t, tryGetKeyIDFromSignature(&packet.Signature{}))
+	assert.Equal(t, "038D1A3EADDBEA9C", tryGetKeyIDFromSignature(&packet.Signature{
+		IssuerKeyId: util.ToPointer(uint64(0x38D1A3EADDBEA9C)),
+	}))
+	assert.Equal(t, "038D1A3EADDBEA9C", tryGetKeyIDFromSignature(&packet.Signature{
+		IssuerFingerprint: []uint8{0xb, 0x23, 0x24, 0xc7, 0xe6, 0xfe, 0x4f, 0x3a, 0x6, 0x26, 0xc1, 0x21, 0x3, 0x8d, 0x1a, 0x3e, 0xad, 0xdb, 0xea, 0x9c},
+	}))
+}