use aes256 for password encryption (#75)

CHANGELOG.md

@@ -41,6 +41,7 @@ DecryptBinaryMessageArmored(privateKey string, passphrase []byte, ciphertext str
 - Improved key and message armoring testing
 - `EncryptSessionKey` now creates encrypted key packets for each valid encryption key in the provided keyring. 
     Returns a byte slice with all the concatenated key packets.
+- Use aes256 chiper for message encryption with password.
 
 ### Fixed
 - Public key armoring headers

crypto/message_test.go

@@ -3,6 +3,7 @@ package crypto
 import (
 	"bytes"
 	"encoding/base64"
+	"io"
 	"testing"
 	"time"
 
@@ -18,6 +19,24 @@ func TestTextMessageEncryptionWithPassword(t *testing.T) {
 	if err != nil {
 		t.Fatal("Expected no error when encrypting, got:", err)
 	}
+	packets := packet.NewReader(bytes.NewReader(encrypted.GetBinary()))
+	var foundSk bool
+	for {
+		var p packet.Packet
+		var errEOF error
+		if p, errEOF = packets.Next(); errEOF == io.EOF {
+			break
+		}
+		sessionKey, ok := p.(*packet.SymmetricKeyEncrypted)
+		if ok {
+			assert.Equal(t, sessionKey.CipherFunc, packet.CipherAES256)
+			foundSk = true
+			break
+		}
+	}
+	if !foundSk {
+		t.Fatal("Expect to found encrypted session key")
+	}
 	// Decrypt data with wrong password
 	_, err = DecryptMessageWithPassword(encrypted, []byte("Wrong password"))
 	assert.NotNil(t, err)

crypto/password.go

@@ -114,6 +114,7 @@ func passwordEncrypt(message []byte, password []byte, isBinary bool) ([]byte, er
 	var outBuf bytes.Buffer
 
 	config := &packet.Config{
+		DefaultCipher: packet.CipherAES256,
 		Time:          getTimeGenerator(),
 	}