# RustCrypto: XSalsa20Poly1305
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[![Docs][docs-image]][docs-link]
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## 🚨 DEPRECATED! 🚨
Please switch to the [`crypto_secretbox`] crate.
This crate is deprecated and will not receive further updates.
## About
**XSalsa20Poly1305** (a.k.a. NaCl [`crypto_secretbox`][1]) is an
[authenticated encryption][2] cipher amenable to fast, constant-time
implementations in software, based on the [Salsa20][3] stream cipher
(with [XSalsa20][4] 192-bit nonce extension) and the [Poly1305][5] universal
hash function, which acts as a message authentication code.
This algorithm has largely been replaced by the newer [ChaCha20Poly1305][6]
(and the associated [XChaCha20Poly1305][7]) AEAD ciphers ([RFC 8439][8]),
but is useful for interoperability with legacy NaCl-based protocols.
[Documentation][docs-link]
## Security Notes
This crate has received one [security audit by Cure53][9] (version 0.8.0), with
no significant findings. We would like to thank [Threema][10] for funding the
audit.
## 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://buildstats.info/crate/xsalsa20poly1305
[crate-link]: https://crates.io/crates/xsalsa20poly1305
[docs-image]: https://docs.rs/xsalsa20poly1305/badge.svg
[docs-link]: https://docs.rs/xsalsa20poly1305/
[license-image]: https://img.shields.io/badge/license-Apache2.0/MIT-blue.svg
[rustc-image]: https://img.shields.io/badge/rustc-1.56+-blue.svg
[chat-image]: https://img.shields.io/badge/zulip-join_chat-blue.svg
[chat-link]: https://rustcrypto.zulipchat.com/#narrow/stream/260038-AEADs
[build-image]: https://github.com/RustCrypto/AEADs/workflows/xsalsa20poly1305/badge.svg?branch=master&event=push
[build-link]: https://github.com/RustCrypto/AEADs/actions
[//]: # (general links)
[`crypto_secretbox`]: https://github.com/RustCrypto/nacl-compat/tree/master/crypto_secretbox
[1]: https://nacl.cr.yp.to/secretbox.html
[2]: https://en.wikipedia.org/wiki/Authenticated_encryption
[3]: https://github.com/RustCrypto/stream-ciphers/tree/master/salsa20
[4]: https://cr.yp.to/snuffle/xsalsa-20081128.pdf
[5]: https://github.com/RustCrypto/universal-hashes/tree/master/poly1305
[6]: https://github.com/RustCrypto/AEADs/tree/master/chacha20poly1305
[7]: https://docs.rs/chacha20poly1305/latest/chacha20poly1305/struct.XChaCha20Poly1305.html
[8]: https://tools.ietf.org/html/rfc8439
[9]: https://cure53.de/pentest-report_rust-libs_2022.pdf
[10]: https://threema.ch/