Add Python Attribute Accessors for PkEncryption (#15)

* Adds missing rust message attribute accessibility and test

* Adds Message impl (pymethods) to enable object creation from python.
Adds python-olm Dependencie (at 3.2.16).
Adds PkEncryption (python-olm) compatibility tests.

---------

Co-authored-by: Damir Jelić <poljar@termina.org.uk>
Co-authored-by: Paarth Shah <mail@shahpaarth.com>

Author: 3 people

src/error.rs

@@ -136,6 +136,8 @@ pub enum PkEncryptionError {
     InvalidKeySize(usize),
     #[error(transparent)]
     Decode(#[from] vodozemac::pk_encryption::Error),
+    #[error(transparent)]
+    Mac(#[from] vodozemac::Base64DecodeError),
 }
 
 pyo3::create_exception!(module, PkInvalidKeySizeException, pyo3::exceptions::PyValueError);
@@ -148,6 +150,7 @@ impl From<PkEncryptionError> for PyErr {
                 PkInvalidKeySizeException::new_err(e.to_string())
             }
             PkEncryptionError::Decode(_) => PkDecodeException::new_err(e.to_string()),
+            PkEncryptionError::Mac(_) => PkDecodeException::new_err(e.to_string()),
         }
     }
 }

src/pk_encryption.rs

@@ -13,17 +13,77 @@ use crate::{
 #[pyclass]
 pub struct Message {
     /// The ciphertext of the message.
+    #[pyo3(get)]
     ciphertext: Vec<u8>,
     /// The message authentication code of the message.
     ///
     /// *Warning*: As stated in the module description, this does not
     /// authenticate the message.
+    #[pyo3(get)]
     mac: Vec<u8>,
     /// The ephemeral Curve25519PublicKey of the message which was used to
     /// derive the individual message key.
+    #[pyo3(get)]
     ephemeral_key: Vec<u8>,
 }
 
+#[pymethods]
+impl Message {
+    /// Create a new Message object from its components.
+    ///
+    /// This constructor creates a Message object that represents an encrypted
+    /// message using the `m.megolm_backup.v1.curve25519-aes-sha2`
+    /// algorithm.
+    ///
+    /// # Arguments
+    /// * `ciphertext` - The encrypted content of the message
+    /// * `mac` - The message authentication code
+    /// * `ephemeral_key` - The ephemeral public key used during encryption
+    #[new]
+    fn new(ciphertext: Vec<u8>, mac: Vec<u8>, ephemeral_key: Vec<u8>) -> Self {
+        Message { ciphertext, mac, ephemeral_key }
+    }
+
+    /// Create a new Message object from unpadded Base64-encoded components.
+    ///
+    /// This function decodes the given Base64 strings and returns a `Message`
+    /// with the resulting byte vectors.
+    ///
+    /// # Arguments
+    /// * `ciphertext` - Unpadded Base64-encoded ciphertext
+    /// * `mac` - Unpadded Base64-encoded message authentication code
+    /// * `ephemeral_key` - Unpadded Base64-encoded ephemeral key
+    #[classmethod]
+    fn from_base64(
+        _cls: &Bound<'_, PyType>,
+        ciphertext: &str,
+        mac: &str,
+        ephemeral_key: &str,
+    ) -> Result<Self, PkEncryptionError> {
+        let decoded_ciphertext = vodozemac::base64_decode(ciphertext)?;
+        let decoded_mac = vodozemac::base64_decode(mac)?;
+        let decoded_ephemeral_key = vodozemac::base64_decode(ephemeral_key)?;
+
+        Ok(Self {
+            ciphertext: decoded_ciphertext,
+            mac: decoded_mac,
+            ephemeral_key: decoded_ephemeral_key,
+        })
+    }
+
+    /// Convert the message components to unpadded Base64-encoded strings.
+    ///
+    /// Returns a tuple of (ciphertext, mac, ephemeral_key) as unpadded Base64
+    /// strings.
+    fn to_base64(&self) -> Result<(String, String, String), PkEncryptionError> {
+        let ciphertext_b64 = vodozemac::base64_encode(&self.ciphertext);
+        let mac_b64 = vodozemac::base64_encode(&self.mac);
+        let ephemeral_key_b64 = vodozemac::base64_encode(&self.ephemeral_key);
+
+        Ok((ephemeral_key_b64, mac_b64, ciphertext_b64))
+    }
+}
+
 /// ☣️  Compat support for libolm's PkDecryption.
 ///
 /// This implements the `m.megolm_backup.v1.curve25519-aes-sha2` described in

tests/pk_encryption_test.py

@@ -1,10 +1,18 @@
-import importlib
-import pytest
+import base64
 
-from vodozemac import Curve25519SecretKey, Curve25519PublicKey, PkEncryption, PkDecryption, PkDecodeException
+import pytest
+from vodozemac import (
+    Curve25519PublicKey,
+    Curve25519SecretKey,
+    Message,
+    PkDecodeException,
+    PkDecryption,
+    PkEncryption,
+)
 
 CLEARTEXT = b"test"
 
+
 class TestClass(object):
     def test_encrypt_decrypt(self):
         d = PkDecryption()
@@ -28,3 +36,41 @@ def test_encrypt_decrypt_with_serialized_keys(self):
 
         decoded = d.decrypt(e.encrypt(CLEARTEXT))
         assert decoded == CLEARTEXT
+
+    def test_encrypt_message_attr(self):
+        """Test that the Message object has accessible Python attributes (mac, ciphertext, ephemeral_key)."""
+        decryption = PkDecryption()
+        encryption = PkEncryption.from_key(decryption.public_key)
+
+        message = encryption.encrypt(CLEARTEXT)
+
+        assert message.mac is not None
+        assert message.ciphertext is not None
+        assert message.ephemeral_key is not None
+
+
+    def test_message_from_invalid_base64(self):
+        """Test that invalid base64 input raises PkDecodeException."""
+        # Test invalid ciphertext    
+        with pytest.raises(PkDecodeException, match="Invalid symbol"):
+            Message.from_base64(
+                "not-valid-base64!@#",  # Invalid base64 for ciphertext
+                base64.b64encode(b"some_mac").decode(),  # Valid base64
+                base64.b64encode(b"some_key").decode()   # Valid base64
+            )
+
+        # Test invalid mac
+        with pytest.raises(PkDecodeException, match="Invalid symbol"):
+            Message.from_base64(
+                base64.b64encode(b"some_text").decode(),
+                "not-valid-base64!@#",  # Invalid base64 for mac
+                base64.b64encode(b"some_key").decode()
+            )
+
+        # Test invalid ephemeral key
+        with pytest.raises(PkDecodeException, match="Invalid symbol"):
+            Message.from_base64(
+                base64.b64encode(b"some_text").decode(),
+                base64.b64encode(b"some_mac").decode(),
+                "not-valid-base64!@#"  # Invalid base64 for ephemeral key
+            )