initial commit

Signed-off-by: Kamal Tufekcic <kamal@lo.sh>

soliton_py/src/call.rs

@@ -0,0 +1,84 @@
+//! Call key derivation for encrypted voice/video.
+
+use pyo3::prelude::*;
+use pyo3::types::PyBytes;
+
+use crate::errors::to_py_err;
+
+/// Call keys for encrypted voice/video media.
+///
+/// Derived from a ratchet session's root key and an ephemeral KEM shared secret.
+/// Keys are role-assigned by fingerprint order — both parties get the same
+/// send/recv assignment without coordination.
+///
+/// Use as a context manager for automatic zeroization::
+///
+///     with ratchet.derive_call_keys(kem_ss, call_id) as keys:
+///         send = keys.send_key()
+///         recv = keys.recv_key()
+///         keys.advance()  # derive next round
+#[pyclass]
+pub struct CallKeys {
+    inner: Option<soliton::call::CallKeys>,
+}
+
+#[pymethods]
+impl CallKeys {
+    /// Current send key (32 bytes).
+    fn send_key<'py>(&self, py: Python<'py>) -> PyResult<Py<PyBytes>> {
+        let inner = self
+            .inner
+            .as_ref()
+            .ok_or_else(|| crate::errors::InvalidDataError::new_err("call keys consumed"))?;
+        Ok(PyBytes::new(py, inner.send_key()).into())
+    }
+
+    /// Current recv key (32 bytes).
+    fn recv_key<'py>(&self, py: Python<'py>) -> PyResult<Py<PyBytes>> {
+        let inner = self
+            .inner
+            .as_ref()
+            .ok_or_else(|| crate::errors::InvalidDataError::new_err("call keys consumed"))?;
+        Ok(PyBytes::new(py, inner.recv_key()).into())
+    }
+
+    /// Advance the call chain — derives fresh keys, zeroizes old ones.
+    ///
+    /// Raises ``ChainExhaustedError`` after 2^24 advances.
+    fn advance(&mut self) -> PyResult<()> {
+        let inner = self
+            .inner
+            .as_mut()
+            .ok_or_else(|| crate::errors::InvalidDataError::new_err("call keys consumed"))?;
+        inner.advance().map_err(to_py_err)
+    }
+
+    /// Zeroize all key material.
+    fn close(&mut self) {
+        self.inner = None;
+    }
+
+    fn __enter__(slf: Py<Self>) -> Py<Self> {
+        slf
+    }
+
+    fn __exit__(
+        &mut self,
+        _exc_type: Option<&Bound<'_, PyAny>>,
+        _exc_val: Option<&Bound<'_, PyAny>>,
+        _exc_tb: Option<&Bound<'_, PyAny>>,
+    ) {
+        self.close();
+    }
+}
+
+impl CallKeys {
+    pub fn from_inner(inner: soliton::call::CallKeys) -> Self {
+        Self { inner: Some(inner) }
+    }
+}
+
+pub fn register(m: &Bound<'_, PyModule>) -> PyResult<()> {
+    m.add_class::<CallKeys>()?;
+    Ok(())
+}