In my last post I described how I implemented the signal-protocol Python library, which provides Python bindings using Pyo3 to an upstream maintained Rust cryptography crate implementing the Signal protocol. I created the the signal-protocol library in order to prototype end-to-end encrypted messaging between journalists and their sources through SecureDrop. In the SecureDrop ecosystem, journalists use a Python project, securedrop-client, hence the need for the Python bindings, and sources use Tor Browser.