Webauthn is a modern approach to hardware based authentication, consisting of a user with an authenticator device, a browser or client that interacts with the device, and a server that is able to generate challenges and verify the authenticator's validity.
Users are able to enroll their own tokens through a registration process to be associated to their accounts, and then are able to login using the token which performas a cryptographic authentication.
This library aims to provide useful functions and frameworks allowing you to integrate webauthn into Rust web servers. This means the library implements the Relying Party component of the FIDO2 workflow. We provide template and example javascript and wasm bindings to demonstrate the browser interactions required.
This library consists of two major parts.
A safe, use-case driven api, which is defined in Webauthn-RS
The low level, protocol level interactions which is defined in Webauthn-Core-RS
We strongly recommend you use the safe api, as webauthn has many sharp edges and ways to hold it wrong!
You can test this library via our demonstration site
Or you can run the demonstration your self locally with:
cd demo_site/webauthn-rs-demo
cargo run
For additional configuration options:
cargo run -- --help
We have extensively tested a variety of keys and devices, not limited to:
- Yubico 5c / 5ci / FIPS / Bio
- TouchID / FaceID (iPhone, iPad, MacBook Pro)
- Android
- Windows Hello (TPM)
- Softtokens
If your key/browser combination don't work (generally due to missing crypto routines) please conduct a compatability test and then open an issue so that we can resolve the issue!
- Pixel 3a / Pixel 4 + Chrome - Does not send correct attestation certificates, and ignores requested algorithms. Not resolved.
- Windows Hello with Older TPMs - Often use RSA-SHA1 signatures over attestation which may allow credential compromise/falsification.
- Windows 10 / Windows 11 + Firefox 98 - When aaguid is meant to be 16 bytes of 0, it emits a single 0 byte. This should be resolved as of 2022-04-17
- BUG in Safari, NOT Apple Passkeys (was: passkeys do not identify themself as a transferable credential, and should be considered to be floating.)
This library has been carefully implemented to follow the w3c standard for webauthn level 3 processing to ensure secure and correct behaviour. We support most major extensions and key types, but we do not claim to be standards complaint because:
- We have enforced extra constraints in the library that go above and beyond the security guarantees the standard offers.
- We do not support certain esoteric options.
- We do not support all cryptographic primitive types (only limited to secure ones).
- A large number of advertised features in webauthn do not function in the real world.
This library has passed a security audit performed by SUSE product security. Other security reviews are welcome!
The current design of the library is open to feedback on how it can be improved - please use this library and contact the project on what can be improved!
A question I expect is why OpenSSL rather than some other pure-Rust cryptographic providers. There are two major justfications.
The first is that if this library will be used in corporate or major deployments, then cryptographic audits may have to be performed. It is much easier to point toward OpenSSL which has already undergone much more review and auditing than using a series of Rust crates which (while still great!) have not seen the same level of scrutiny.
The second is that OpenSSL is the only library I have found that allows us to reconstruct an EC public key from its X/Y points or an RSA public key from its n/e for use with signature verification. Without this, we are not able to parse authenticator credentials to perform authentication.
- Specification: https://www.w3.org/TR/webauthn-3
- JSON details: https://fidoalliance.org/specs/fido-v2.0-rd-20180702/fido-server-v2.0-rd-20180702.html
- Write up on interactions: https://medium.com/@herrjemand/introduction-to-webauthn-api-5fd1fb46c285