Add binary message helpers (#61)

* Add EncryptBinaryMessageArmored helper function to generate an armored PGP message given binary data and an armored public key

* Add DecryptBinaryMessageArmored helper function to decrypt armored PGP message into binary data

* Streamline the code and fix naming pattern + tests

README.md

@@ -148,11 +148,17 @@ const privkey = `-----BEGIN PGP PRIVATE KEY BLOCK-----
 
 const passphrase = []byte(`the passphrase of the private key`) // Passphrase of the privKey
 
-// encrypt message using public key
+// encrypt plain text message using public key
 armor, err := helper.EncryptMessageArmored(pubkey, "plain text")
 
-// decrypt armored encrypted message using the private key
+// encrypt binary message using public key
+armor, err := helper.EncryptBinaryMessageArmored(pubkey, []byte("plain text"))
+
+// decrypt armored encrypted message using the private key and got plain text
 decrypted, err := helper.DecryptMessageArmored(privkey, passphrase, armor)
+
+// decrypt armored encrypted message using the private key and got binary
+decrypted, err := helper.DecryptBinaryMessageArmored(privkey, passphrase, armor)
 ```
 
 With signatures:

helper/helper.go

@@ -43,30 +43,8 @@ func DecryptMessageWithPassword(password []byte, ciphertext string) (plaintext s
 
 // EncryptMessageArmored generates an armored PGP message given a plaintext and
 // an armored public key.
-func EncryptMessageArmored(key, plaintext string) (ciphertext string, err error) {
-	var publicKey *crypto.Key
-	var publicKeyRing *crypto.KeyRing
-	var pgpMessage *crypto.PGPMessage
-
-	var message = crypto.NewPlainMessageFromString(plaintext)
-
-	if publicKey, err = crypto.NewKeyFromArmored(key); err != nil {
-		return "", err
-	}
-
-	if publicKeyRing, err = crypto.NewKeyRing(publicKey); err != nil {
-		return "", err
-	}
-
-	if pgpMessage, err = publicKeyRing.Encrypt(message, nil); err != nil {
-		return "", err
-	}
-
-	if ciphertext, err = pgpMessage.GetArmored(); err != nil {
-		return "", err
-	}
-
-	return ciphertext, nil
+func EncryptMessageArmored(key, plaintext string) (string, error) {
+	return encryptMessageArmored(key, crypto.NewPlainMessageFromString(plaintext))
 }
 
 // EncryptSignMessageArmored generates an armored signed PGP message given a
@@ -116,30 +94,10 @@ func EncryptSignMessageArmored(
 // and its passphrase.
 func DecryptMessageArmored(
 	privateKey string, passphrase []byte, ciphertext string,
-) (plaintext string, err error) {
-	var privateKeyObj, privateKeyUnlocked *crypto.Key
-	var privateKeyRing *crypto.KeyRing
-	var pgpMessage *crypto.PGPMessage
-	var message *crypto.PlainMessage
+) (string, error) {
+	message, err := decryptMessageArmored(privateKey, passphrase, ciphertext)
 
-	if privateKeyObj, err = crypto.NewKeyFromArmored(privateKey); err != nil {
-		return "", err
-	}
-
-	if privateKeyUnlocked, err = privateKeyObj.Unlock(passphrase); err != nil {
-		return "", err
-	}
-	defer privateKeyUnlocked.ClearPrivateParams()
-
-	if privateKeyRing, err = crypto.NewKeyRing(privateKeyUnlocked); err != nil {
-		return "", err
-	}
-
-	if pgpMessage, err = crypto.NewPGPMessageFromArmored(ciphertext); err != nil {
-		return "", err
-	}
-
-	if message, err = privateKeyRing.Decrypt(pgpMessage, nil, 0); err != nil {
+	if err != nil {
 		return "", err
 	}
 
@@ -240,3 +198,85 @@ func DecryptVerifyAttachment(
 
 	return message.GetBinary(), nil
 }
+
+// EncryptBinaryMessageArmored generates an armored PGP message given a binary data and
+// an armored public key.
+func EncryptBinaryMessageArmored(key string, data []byte) (string, error) {
+	return encryptMessageArmored(key, crypto.NewPlainMessage(data))
+}
+
+// DecryptBinaryMessageArmored decrypts an armored PGP message given a private key
+// and its passphrase.
+func DecryptBinaryMessageArmored(privateKey string, passphrase []byte, ciphertext string) ([]byte, error) {
+	message, err := decryptMessageArmored(privateKey, passphrase, ciphertext)
+
+	if err != nil {
+		return nil, err
+	}
+
+	return message.GetBinary(), nil
+}
+
+func encryptMessageArmored(key string, message *crypto.PlainMessage) (string, error) {
+	publicKey, err := crypto.NewKeyFromArmored(key)
+
+	if err != nil {
+		return "", err
+	}
+
+	publicKeyRing, err := crypto.NewKeyRing(publicKey)
+
+	if err != nil {
+		return "", err
+	}
+
+	pgpMessage, err := publicKeyRing.Encrypt(message, nil)
+
+	if err != nil {
+		return "", err
+	}
+
+	ciphertext, err := pgpMessage.GetArmored()
+
+	if err != nil {
+		return "", err
+	}
+
+	return ciphertext, nil
+}
+
+func decryptMessageArmored(privateKey string, passphrase []byte, ciphertext string) (*crypto.PlainMessage, error) {
+	privateKeyObj, err := crypto.NewKeyFromArmored(privateKey)
+
+	if err != nil {
+		return nil, err
+	}
+
+	privateKeyUnlocked, err := privateKeyObj.Unlock(passphrase)
+
+	if err != nil {
+		return nil, err
+	}
+
+	defer privateKeyUnlocked.ClearPrivateParams()
+
+	privateKeyRing, err := crypto.NewKeyRing(privateKeyUnlocked)
+
+	if err != nil {
+		return nil, err
+	}
+
+	pgpMessage, err := crypto.NewPGPMessageFromArmored(ciphertext)
+
+	if err != nil {
+		return nil, err
+	}
+
+	message, err := privateKeyRing.Decrypt(pgpMessage, nil, 0)
+
+	if err != nil {
+		return nil, err
+	}
+
+	return message, nil
+}

helper/helper_test.go

@@ -130,3 +130,27 @@ func TestAttachmentEncryptionVerification(t *testing.T) {
 
 	assert.Exactly(t, attachment, decrypted)
 }
+
+func TestArmoredBinaryMessageEncryption(t *testing.T) {
+	plainData := []byte("Secret message")
+
+	armored, err := EncryptBinaryMessageArmored(readTestFile("keyring_publicKey", false), plainData)
+
+	if err != nil {
+		t.Fatal("Expected no error when encrypting, got:", err)
+	}
+
+	assert.Exactly(t, true, crypto.IsPGPMessage(armored))
+
+	decrypted, err := DecryptBinaryMessageArmored(
+		readTestFile("keyring_privateKey", false),
+		testMailboxPassword, // Password defined in base_test
+		armored,
+	)
+
+	if err != nil {
+		t.Fatal("Expected no error when decrypting, got:", err)
+	}
+
+	assert.Exactly(t, plainData, decrypted)
+}