can now pass a PublicKey to SigningMethodRSA.Verify

rsa.go

@@ -44,6 +44,9 @@ func (m *SigningMethodRSA) Alg() string {
 	return m.Name
 }
 
+// Implements the Verify method from SigningMethod
+// For this signing method, must be either a PEM encoded PKCS1 or PKCS8 RSA private key as
+// []byte, or an rsa.PrivateKey structure.
 func (m *SigningMethodRSA) Verify(signingString, signature string, key interface{}) error {
 	var err error
 
@@ -53,21 +56,25 @@ func (m *SigningMethodRSA) Verify(signingString, signature string, key interface
 		return err
 	}
 
-	if keyBytes, ok := key.([]byte); ok {
-		var rsaKey *rsa.PublicKey
-		if rsaKey, err = m.parsePublicKey(keyBytes); err != nil {
+	var rsaKey *rsa.PublicKey
+
+	switch k := key.(type) {
+	case []byte:
+		if rsaKey, err = m.parsePublicKey(k); err != nil {
 			return err
 		}
-
-		// Create hasher
-		hasher := m.Hash.New()
-		hasher.Write([]byte(signingString))
-
-		// Verify the signature
-		return rsa.VerifyPKCS1v15(rsaKey, m.Hash, hasher.Sum(nil), sig)
-	} else {
+	case *rsa.PublicKey:
+		rsaKey = k
+	default:
 		return ErrInvalidKey
 	}
+
+	// Create hasher
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Verify the signature
+	return rsa.VerifyPKCS1v15(rsaKey, m.Hash, hasher.Sum(nil), sig)
 }
 
 // Implements the Sign method from SigningMethod

rsa_test.go

@@ -78,6 +78,21 @@ func TestRSASign(t *testing.T) {
 	}
 }
 
+func TestRSAVerifyWithPreParsedPrivateKey(t *testing.T) {
+	key, _ := ioutil.ReadFile("test/sample_key.pub")
+	method := GetSigningMethod("RS256").(*SigningMethodRSA)
+	parsedKey, err := method.parsePublicKey(key)
+	if err != nil {
+		t.Fatal(err)
+	}
+	testData := rsaTestData[0]
+	parts := strings.Split(testData.tokenString, ".")
+	err = method.Verify(strings.Join(parts[0:2], "."), parts[2], parsedKey)
+	if err != nil {
+		t.Errorf("[%v] Error while verifying key: %v", testData.name, err)
+	}
+}
+
 func TestRSAWithPreParsedPrivateKey(t *testing.T) {
 	key, _ := ioutil.ReadFile("test/sample_key")
 	method := GetSigningMethod("RS256").(*SigningMethodRSA)