Rustls is a modern TLS library written in Rust.

Rustls is used in production at many organizations and projects. We aim to maintain reasonable API surface stability but the API may evolve as we make changes to accomodate new features or performance improvements.

We have a roadmap for our future plans. We also have benchmarks to prevent performance regressions and to let you evaluate rustls on your target hardware.

If you'd like to help out, please see CONTRIBUTING.md.

The detailed list of changes in each release can be found at https://github.com/rustls/rustls/releases.

https://docs.rs/rustls/

Rustls is a TLS library that aims to provide a good level of cryptographic security, requires no configuration to achieve that security, and provides no unsafe features or obsolete cryptography by default.

• TLS1.2 and TLS1.3.
• ECDSA, Ed25519 or RSA server authentication by clients.
• ECDSA, Ed25519 or RSA server authentication by servers.
• Forward secrecy using ECDHE; with curve25519, nistp256 or nistp384 curves.
• AES128-GCM and AES256-GCM bulk encryption, with safe nonces.
• ChaCha20-Poly1305 bulk encryption (RFC7905).
• ALPN support.
• SNI support.
• Tunable fragment size to make TLS messages match size of underlying transport.
• Optional use of vectored IO to minimise system calls.
• TLS1.2 session resumption.
• TLS1.2 resumption via tickets (RFC5077).
• TLS1.3 resumption via tickets or session storage.
• TLS1.3 0-RTT data for clients.
• TLS1.3 0-RTT data for servers.
• Server and optional client authentication.
• Extended master secret support (RFC7627).
• Exporters (RFC5705).
• OCSP stapling by servers.

For reasons explained in the manual, rustls does not and will not support:

• SSL1, SSL2, SSL3, TLS1 or TLS1.1.
• RC4.
• DES or triple DES.
• EXPORT ciphersuites.
• MAC-then-encrypt ciphersuites.
• Ciphersuites without forward secrecy.
• Renegotiation.
• Kerberos.
• TLS 1.2 protocol compression.
• Discrete-log Diffie-Hellman.
• Automatic protocol version downgrade.
• Using CA certificates directly to authenticate a server/client (often called "self-signed certificates"). Rustls' default certificate verifier does not support using a trust anchor as both a CA certificate and an end-entity certificate in order to limit complexity and risk in path building. While dangerous, all authentication can be turned off if required -- see the example code.

There are plenty of other libraries that provide these features should you need them.

While Rustls itself is platform independent, by default it uses aws-lc-rs for implementing the cryptography in TLS. See the aws-lc-rs FAQ for more details of the platform/architecture support constraints in aws-lc-rs.

ring is also available via the ring crate feature: see the supported ring target platforms.

By providing a custom instance of the crypto::CryptoProvider struct, you can replace all cryptography dependencies of rustls. This is a route to being portable to a wider set of architectures and environments, or compliance requirements. See the crypto::CryptoProvider documentation for more details.

Specifying default-features = false when depending on rustls will remove the dependency on aws-lc-rs.

Rustls requires Rust 1.61 or later.

Since Rustls 0.22 it has been possible to choose the provider of the cryptographic primitives that Rustls uses. This may be appealing if you have specific platform, compliance or feature requirements that aren't met by the default provider, aws-lc-rs.

Users that wish to customize the provider in use can do so when constructing ClientConfig and ServerConfig instances using the with_crypto_provider method on the respective config builder types. See the crypto::CryptoProvider documentation for more details.

Rustls ships with two built-in providers controlled with associated feature flags:

• aws-lc-rs - enabled by default, available with the aws_lc_rs feature flag enabled.
• ring - available with the ring feature flag enabled.

See the documentation for crypto::CryptoProvider for details on how providers are selected.

The community has also started developing third-party providers for Rustls:

• rustls-mbedtls-provider - a provider that uses mbedtls for cryptography.
• boring-rustls-provider - a work-in-progress provider that uses boringssl for cryptography.
• rustls-rustcrypto - an experimental provider that uses the crypto primitives from RustCrypto for cryptography.

We also provide a simple example of writing your own provider in the custom-provider example. This example implements a minimal provider using parts of the RustCrypto ecosystem.

See the Making a custom CryptoProvider section of the documentation for more information on this topic.

Our examples directory contains demos that show how to handle I/O using the stream::Stream helper, as well as more complex asynchronous I/O using mio. If you're already using Tokio for an async runtime you may prefer to use tokio-rustls instead of interacting with rustls directly.

The mio based examples are the most complete, and discussed below. Users new to Rustls may prefer to look at the simple client/server examples before diving in to the more complex MIO examples.

The MIO client example program is named tlsclient-mio. The interface looks like:

Connects to the TLS server at hostname:PORT. The default PORT is 443. By default, this reads a request from stdin (to EOF) before making the connection. --http replaces this with a basic HTTP GET request for /. If --cafile is not supplied, a built-in set of CA certificates are used from the webpki-roots crate. Usage: tlsclient-mio [options] [--suite SUITE ...] [--proto PROTO ...] [--protover PROTOVER ...] <hostname> tlsclient-mio (--version | -v) tlsclient-mio (--help | -h) Options: -p, --port PORT Connect to PORT [default: 443]. --http Send a basic HTTP GET request for /. --cafile CAFILE Read root certificates from CAFILE. --auth-key KEY Read client authentication key from KEY. --auth-certs CERTS Read client authentication certificates from CERTS. CERTS must match up with KEY. --protover VERSION Disable default TLS version list, and use VERSION instead. May be used multiple times. --suite SUITE Disable default cipher suite list, and use SUITE instead. May be used multiple times. --proto PROTOCOL Send ALPN extension containing PROTOCOL. May be used multiple times to offer several protocols. --no-tickets Disable session ticket support. --no-sni Disable server name indication support. --insecure Disable certificate verification. --verbose Emit log output. --max-frag-size M Limit outgoing messages to M bytes. --version, -v Show tool version. --help, -h Show this screen. 

Some sample runs:

$ cargo run --bin tlsclient-mio -- --http mozilla-modern.badssl.com HTTP/1.1 200 OK Server: nginx/1.6.2 (Ubuntu) Date: Wed, 01 Jun 2016 18:44:00 GMT Content-Type: text/html Content-Length: 644 (...) 

or

$ cargo run --bin tlsclient-mio -- --http expired.badssl.com TLS error: InvalidCertificate(Expired) Connection closed 

The MIO server example program is named tlsserver-mio. The interface looks like:

Runs a TLS server on :PORT. The default PORT is 443. `echo' mode means the server echoes received data on each connection. `http' mode means the server blindly sends a HTTP response on each connection. `forward' means the server forwards plaintext to a connection made to localhost:fport. `--certs' names the full certificate chain, `--key' provides the RSA private key. Usage: tlsserver-mio --certs CERTFILE --key KEYFILE [--suite SUITE ...] [--proto PROTO ...] [--protover PROTOVER ...] [options] echo tlsserver-mio --certs CERTFILE --key KEYFILE [--suite SUITE ...] [--proto PROTO ...] [--protover PROTOVER ...] [options] http tlsserver-mio --certs CERTFILE --key KEYFILE [--suite SUITE ...] [--proto PROTO ...] [--protover PROTOVER ...] [options] forward <fport> tlsserver-mio (--version | -v) tlsserver-mio (--help | -h) Options: -p, --port PORT Listen on PORT [default: 443]. --certs CERTFILE Read server certificates from CERTFILE. This should contain PEM-format certificates in the right order (the first certificate should certify KEYFILE, the last should be a root CA). --key KEYFILE Read private key from KEYFILE. This should be a RSA private key or PKCS8-encoded private key, in PEM format. --ocsp OCSPFILE Read DER-encoded OCSP response from OCSPFILE and staple to certificate. Optional. --auth CERTFILE Enable client authentication, and accept certificates signed by those roots provided in CERTFILE. --crl CRLFILE ... Perform client certificate revocation checking using the DER-encoded CRLFILE. May be used multiple times. --require-auth Send a fatal alert if the client does not complete client authentication. --resumption Support session resumption. --tickets Support tickets. --protover VERSION Disable default TLS version list, and use VERSION instead. May be used multiple times. --suite SUITE Disable default cipher suite list, and use SUITE instead. May be used multiple times. --proto PROTOCOL Negotiate PROTOCOL using ALPN. May be used multiple times. --verbose Emit log output. --version, -v Show tool version. --help, -h Show this screen. 

Here's a sample run; we start a TLS echo server, then connect to it with openssl and tlsclient-mio:

$ cargo run --bin tlsserver-mio -- --certs test-ca/rsa/end.fullchain --key test-ca/rsa/end.rsa -p 8443 echo & $ echo hello world | openssl s_client -ign_eof -quiet -connect localhost:8443 depth=2 CN = ponytown RSA CA verify error:num=19:self signed certificate in certificate chain hello world ^C $ echo hello world | cargo run --bin tlsclient-mio -- --cafile test-ca/rsa/ca.cert -p 8443 localhost hello world ^C 

Rustls is distributed under the following three licenses:

• Apache License version 2.0.
• MIT license.
• ISC license.

These are included as LICENSE-APACHE, LICENSE-MIT and LICENSE-ISC respectively. You may use this software under the terms of any of these licenses, at your option.

• Joe Birr-Pixton (@ctz, Project Founder - full-time funded by Prossimo)
• Dirkjan Ochtman (@djc, Co-maintainer)
• Daniel McCarney (@cpu, Co-maintainer - full-time funded by Prossimo)
• Josh Aas (@bdaehlie, Project Management)

This project adopts the Rust Code of Conduct. Please email rustls-mod@googlegroups.com to report any instance of misconduct, or if you have any comments or questions on the Code of Conduct.