A no-network-IO implementation of a state machine that handles E2EE for [Matrix] clients.

Usage

If you're just trying to write a Matrix client or bot in Rust, you're probably looking for [matrix-sdk] instead.

However, if you're looking to add E2EE to an existing Matrix client or library, read on.

The state machine works in a push/pull manner:

```rust,no_run use std::{collections::BTreeMap, convert::TryFrom};

use matrixsdkcrypto::{OlmMachine, OlmError}; use ruma::{ api::client::sync::syncevents::v3::{ToDevice, DeviceLists}, deviceid, user_id, };

[tokio::main]

async fn main() -> Result<(), OlmError> { let alice = userid!("@alice:example.org"); let machine = OlmMachine::new(&alice, deviceid!("DEVICEID")).await;

let to_device_events = ToDevice::default();
let changed_devices = DeviceLists::default();
let one_time_key_counts = BTreeMap::default();
let unused_fallback_keys = Some(Vec::new());

// Push changes that the server sent to us in a sync response.
let decrypted_to_device = machine.receive_sync_changes(
    to_device_events,
    &changed_devices,
    &one_time_key_counts,
    unused_fallback_keys.as_deref(),
).await?;

// Pull requests that we need to send out.
let outgoing_requests = machine.outgoing_requests().await?;

// Send the requests here out and call machine.mark_request_as_sent().

Ok(())

} ```

Room key sharing algorithm

The decision tree below visualizes the way this crate decides whether a room key will be shared with a requester upon a key request.

Crate Feature Flags

The following crate feature flags are available: