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.
If you'd like to help out, please see CONTRIBUTING.md.
Release history can be found on GitHub.
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.
- Client authentication by clients.
- Client authentication by servers.
- 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, it uses
ring for implementing the cryptography in
TLS. As a result, rustls only runs on platforms
supported by ring. At the time of writing, this means 32-bit ARM, Aarch64 (64-bit ARM),
x86, x86-64, LoongArch64, 32-bit & 64-bit Little Endian MIPS, 32-bit PowerPC (Big Endian),
64-bit PowerPC (Big and Little Endian), 64-bit RISC-V, and s390x. We do not presently
support WebAssembly.
For more information, see the supported ring target platforms.
Rustls requires Rust 1.61 or later.
There are two example programs which use mio to do asynchronous IO.
The 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 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 (GitHub: @ctz)
- Dirkjan Ochtman (GitHub: @djc)
- Daniel McCarney (GitHub: @cpu)
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.