Fix various keys issues (#117)

* Fix armouring headers for public keys
* Fix error for session key decryption failure

crypto/attachment_test.go

@@ -103,7 +103,7 @@ func TestAttachmentDecrypt(t *testing.T) {
 	assert.Exactly(t, message, redecData)
 }
 
-func TestAttachmentDecrypt2(t *testing.T) {
+func TestAttachmentDecryptStatic(t *testing.T) {
 	passphrase := []byte("wUMuF/lkDPYWH/0ZqqY8kJKw7YJg6kS")
 	keyPacket, err := base64.StdEncoding.DecodeString(readTestFile("att_keypacket", false))
 	if err != nil {

crypto/key.go

@@ -200,7 +200,11 @@ func (key *Key) Armor() (string, error) {
 		return "", err
 	}
 
-	return armor.ArmorWithType(serialized, constants.PrivateKeyHeader)
+	if key.IsPrivate() {
+		return armor.ArmorWithType(serialized, constants.PrivateKeyHeader)
+	}
+
+	return armor.ArmorWithType(serialized, constants.PublicKeyHeader)
 }
 
 // ArmorWithCustomHeaders returns the armored key as a string, with

crypto/keyring_session.go

@@ -55,15 +55,15 @@ Loop:
 	}
 
 	if !hasPacket {
-		return nil, errors.Wrap(err, "gopenpgp: couldn't find a session key packet that could be decrypted")
+		return nil, errors.Wrap(err, "gopenpgp: couldn't find a session key packet")
 	}
 
 	if decryptErr != nil {
 		return nil, errors.Wrap(decryptErr, "gopenpgp: error in decrypting")
 	}
 
-	if ek == nil {
-		return nil, errors.New("gopenpgp: unable to decrypt session key")
+	if ek == nil || ek.Key == nil {
+		return nil, errors.New("gopenpgp: unable to decrypt session key: no valid decryption key")
 	}
 
 	return newSessionKeyFromEncrypted(ek)

crypto/sessionkey_test.go

@@ -1,6 +1,7 @@
 package crypto
 
 import (
+	"encoding/base64"
 	"testing"
 
 	"github.com/ProtonMail/gopenpgp/v2/constants"
@@ -210,3 +211,31 @@ func TestDataPacketEncryptionWithCompression(t *testing.T) {
 	}
 	assert.Exactly(t, message.GetString(), decrypted.GetString())
 }
+
+func TestAsymmetricKeyPacketDecryptionFailure(t *testing.T) {
+	passphrase := []byte("passphrase")
+	keyPacket, err := base64.StdEncoding.DecodeString(readTestFile("sessionkey_packet", false))
+	if err != nil {
+		t.Error("Expected no error while decoding key packet, got:" + err.Error())
+	}
+
+	pk, err := NewKeyFromArmored(readTestFile("sessionkey_key", false))
+	if err != nil {
+		t.Error("Expected no error while unarmoring private key, got:" + err.Error())
+	}
+
+	uk, err := pk.Unlock(passphrase)
+	if err != nil {
+		t.Error("Expected no error while unlocking private key, got:" + err.Error())
+	}
+
+	defer uk.ClearPrivateParams()
+
+	ukr, err := NewKeyRing(uk)
+	if err != nil {
+		t.Error("Expected no error while building private keyring, got:" + err.Error())
+	}
+
+	_, err = ukr.DecryptSessionKey(keyPacket)
+	assert.Error(t, err, "gopenpgp: unable to decrypt session key")
+}

crypto/testdata/sessionkey_key

@@ -0,0 +1,31 @@
+-----BEGIN PGP PRIVATE KEY BLOCK-----
+Version: BCPG C# v1.8.8.0
+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+=grHo
+-----END PGP PRIVATE KEY BLOCK-----

crypto/testdata/sessionkey_packet

@@ -0,0 +1 @@
+wcBMAykFqdVSI1GtAQf+ID+pqYcKMsHUeos3qQ/2zJ+8XguKg8/bpW66XXQJOlXO/yWP5NplcuBIZcDfnJ9gk8cpOg8QXCzgk4BqmpuDVrShn0M4UnmcISC43i5L8+tS63Vv0LHxdcj5ADYAFKz0bRKjhf3JFjibttn8nuEEJJVNi4zUwC2lVr8v5THxj6SpZtNrBeFaaQ0Y78q8rNqPZtNqq2TcCmlVj4d+VnNnbkEOrizw97I9P784L169s0kVb3S0t0r1Y/mOPxq3T1EXDbo37quveZjKHgkuT/1FTOEO2yzqPOhyRlF6MuQYlPJMZv9pHwNDCyfm8WQutzpRK+MI4AcqVyALC4rU3w9JNg==