Fix: use verifyTime in the config time instead of Now()

When decrypting message, we have to use verifyTime in the config
otherwise signatures not valid at verifyTime but valid at Now()
will be seen as valid.

crypto/keyring_test.go

@@ -3,11 +3,13 @@ package crypto
 import (
 	"crypto/ed25519"
 	"crypto/rsa"
+	"errors"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 
 	"github.com/ProtonMail/go-crypto/openpgp/ecdh"
+	"github.com/ProtonMail/gopenpgp/v2/constants"
 )
 
 var testSymmetricKey []byte
@@ -231,3 +233,43 @@ func TestKeyringCapabilities(t *testing.T) {
 	assert.True(t, keyRingTestMultiple.CanVerify())
 	assert.True(t, keyRingTestMultiple.CanEncrypt())
 }
+
+func TestVerificationTime(t *testing.T) {
+	message := NewPlainMessageFromString("Hello")
+	pgp.latestServerTime = 1632312383
+	defer func() {
+		pgp.latestServerTime = testTime
+	}()
+	enc, err := keyRingTestPublic.Encrypt(
+		message,
+		keyRingTestPrivate,
+	)
+
+	if err != nil {
+		t.Fatalf("Encryption error: %v", err)
+	}
+	_, err = keyRingTestPrivate.Decrypt(
+		enc,
+		keyRingTestPublic,
+		392039755,
+	)
+	if err == nil {
+		t.Fatal("No signature error")
+	}
+	castedErr := &SignatureVerificationError{}
+	isType := errors.As(err, castedErr)
+	if !isType {
+		t.Fatalf("No signature error %v", err)
+	}
+	if castedErr.Status != constants.SIGNATURE_FAILED {
+		t.Fatalf("Wrong status %v", castedErr)
+	}
+	_, err = keyRingTestPrivate.Decrypt(
+		enc,
+		keyRingTestPublic,
+		0,
+	)
+	if err != nil {
+		t.Fatalf("Got an error while decrypting %v", err)
+	}
+}