# ChaCha20Poly1305: Authenticated Encryption Cipher
[![crate][crate-image]][crate-link]
[![Docs][docs-image]][docs-link]
![Apache2/MIT licensed][license-image]
![Rust Version][rustc-image]
![Maintenance Status: Experimental][maintenance-image]
[![Build Status][build-image]][build-link]
**ChaCha20Poly1305** ([RFC 8439][1]) is an [Authenticated Encryption with Associated Data (AEAD)][2]
cipher amenable to fast, constant-time implementations in software, based on
the [ChaCha20][3] stream cipher and [Poly1305][4] universal hash function.
This crate also contains an implementation of **XChaCha20Poly1305**: a variant
of ChaCha20Poly1305 with an extended 192-bit (24-byte) nonce.
[Documentation][docs-link]
## Security Warning
No security audits of this crate have ever been performed, and it has not been
thoroughly assessed to ensure its operation is constant-time on common CPU
architectures.
USE AT YOUR OWN RISK!
## License
Licensed under either of:
* [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0)
* [MIT license](http://opensource.org/licenses/MIT)
at your option.
### Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
dual licensed as above, without any additional terms or conditions.
[//]: # (badges)
[crate-image]: https://img.shields.io/crates/v/chacha20poly1305.svg
[crate-link]: https://crates.io/crates/chacha20poly1305
[docs-image]: https://docs.rs/chacha20poly1305/badge.svg
[docs-link]: https://docs.rs/chacha20poly1305/
[license-image]: https://img.shields.io/badge/license-Apache2.0/MIT-blue.svg
[rustc-image]: https://img.shields.io/badge/rustc-1.36+-blue.svg
[maintenance-image]: https://img.shields.io/badge/maintenance-experimental-blue.svg
[build-image]: https://travis-ci.com/RustCrypto/AEADs.svg?branch=master
[build-link]: https://travis-ci.com/RustCrypto/AEADs
[//]: # (general links)
[1]: https://tools.ietf.org/html/rfc8439
[2]: https://en.wikipedia.org/wiki/Authenticated_encryption
[3]: https://github.com/RustCrypto/stream-ciphers/tree/master/chacha20
[4]: https://github.com/RustCrypto/universal-hashes/tree/master/poly1305