#async #tls #ssl #rustls


Asynchronous TLS/SSL streams using Rustls

8 releases (breaking)

0.11.0 Dec 9, 2020
0.10.0 Sep 9, 2020
0.9.0 Jul 15, 2020
0.7.0 Mar 30, 2020
0.1.0 May 31, 2019

#11 in Asynchronous

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Used in 60 crates (27 directly)


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Async TLS/SSL streams using Rustls.

Maintenance Notice

I, Florian Gilcher, am currently the main maintainer of async-tls. Due to general workload, I would like the hand the maintenance off to someone else carrying the general vision of async-tls:

  • Runtime-independence
  • Backend-independence (currently not implemented)
  • Focused on use-case based configuration rather then exposing all configurations

I expect applicants for maintainership to present a committment of at least 4h of time/week initially, so I recommend getting corporate backing first. The number isn't strict, but I want the process to improve maintenance. I'm happy with a group of multiple maintainers.

I commit to weekly feedback of 30 minutes for the first 2 months - more in the initial days of handover.

If interested, please reach out to me at through email.


async-tls can be used both in server and client programs. To save compilation times, you can switch off parts of this for faster compile times.

To only use async-tls on a client, deactivate default features and use the "client" feature.

version = "0.8"
default-features = false
features = ["client"]

To only use async-tls on for the server side, deactivate default features and use the "server" feature.

version = "0.8"
default-features = false
features = ["server"]

Simple Client

use async_tls::TlsConnector;
use async_std::net::TcpStream;

// ...

let tcp_stream = TcpStream::connect("rust-lang.org:443").await?;
let connector = TlsConnector::default();
let mut tls_stream = connector.connect("www.rust-lang.org", tcp_stream).await?;

// ...

Client Example Program

See examples/client. You can run it with:

cd examples/client
cargo run -- hsts.badssl.com

Server Example Program

See examples/server. You can run it with:

cd examples/server
cargo run -- --cert ../../tests/end.cert --key ../../tests/end.rsa

and point the client at it with:

cd examples/client
cargo run -- --port 8080 --domain localhost --cafile ../../tests/end.chain

NOTE: Don't ever use those certificate files anywhere but for testing!


This crate uses #![deny(unsafe_code)] to ensure everything is implemented in 100% Safe Rust.

License & Origin

This project is licensed under either of

at your option.

This started as a fork of tokio-rustls.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in async-tls by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.


~200K SLoC