## The OPAQUE key exchange protocol
[OPAQUE](https://eprint.iacr.org/2018/163.pdf) is an augmented password-authenticated key exchange protocol. It allows a
client to authenticate to a server using a password, without ever having to expose the plaintext password to the server.
This implementation is based on [RFC 9807](https://datatracker.ietf.org/doc/rfc9807/).
This is a fork of [facebook/opaque-ke](https://github.com/facebook/opaque-ke) maintained
by [VexaHub](https://github.com/vexahub), targeting the latest **RustCrypto ecosystem**.
Background
----------
Augmented Password Authenticated Key Exchange (aPAKE) protocols are designed to provide password authentication and
mutually authenticated key exchange without relying on PKI (except during user/password registration) and without
disclosing passwords to servers or other entities other than the client machine.
OPAQUE is a PKI-free aPAKE that is secure against pre-computation attacks and capable of using a secret salt.
Documentation
-------------
The API can be found [here](https://docs.rs/opaque-vx/) along with an example for usage. More examples can be found
in
the [examples](./examples) directory.
Installation
------------
Add the following line to the dependencies of your `Cargo.toml`:
```
opaque-vx = "1.0.0-rc.0"
```
### Minimum Supported Rust Version
Rust **1.90** or higher.
Audit
-----
This library was audited by NCC Group in June of 2021. The audit was sponsored by WhatsApp for its use
in [enabling end-to-end encrypted backups](https://engineering.fb.com/2021/09/10/security/whatsapp-e2ee-backups/).
The audit found issues in release `v0.5.0`, and the fixes were subsequently incorporated into release `v1.2.0`. See
the [full audit report here](https://research.nccgroup.com/2021/12/13/public-report-whatsapp-opaque-ke-cryptographic-implementation-review/).
Resources
---------
- [OPAQUE academic publication](https://eprint.iacr.org/2018/163.pdf), including formal definitions and a proof of
security
- [RFC 9807](https://datatracker.ietf.org/doc/rfc9807/), containing a detailed (byte-level) specification for OPAQUE
- ["Let's talk about PAKE"](https://blog.cryptographyengineering.com/2018/10/19/lets-talk-about-pake/), an introductory
blog post written by Matthew Green that covers OPAQUE
- [@serenity-kit/opaque](https://github.com/serenity-kit/opaque), a WebAssembly package for this library
- [opaque-wasm](https://github.com/marucjmar/opaque-wasm), a WebAssembly package for this library. A comparison between
`@serenity-kit/opaque` and `opaque-wasm` can be
found [here](https://opaque-documentation.netlify.app/docs/faq#how-does-it-compare-to-opaque-wasm)
- [react-native-opaque](https://github.com/serenity-kit/react-native-opaque), a React Native package for this library
matching the API of `@serenity-kit/opaque`
Contributors
------------
This fork is maintained by [VexaHub](https://github.com/vexahub).
The original authors are Kevin Lewi ([@kevinlewi](https://github.com/kevinlewi)) and François
Garillot ([@huitseeker](https://github.com/huitseeker)).
To learn more about contributing to this project, [see this document](./CONTRIBUTING.md).
#### Acknowledgments
Special thanks go to Hugo Krawczyk and Chris Wood for helping to clarify discrepancies and making suggestions for
improving
this implementation. Additional credit goes to @daxpedda for adding no_std support, p256 support, and making other
general
improvements to the library.
License
-------
This project is dual-licensed under either the [MIT license](./LICENSE-MIT)
or the [Apache License, Version 2.0](./LICENSE-APACHE).
You may select, at your option, one of the above-listed licenses.