# \[ANN\] u2f - universal second factor **URL:** \ **Category:** Community\ **Tags:** security, announce\ **Created:** [June 30, 2021, 3:46pm UTC](https://discuss.ocaml.org/t/ann-u2f-universal-second-factor/8078 "2021-06-30T15:46:44Z")\ **Posts on this page:** 1\ **Showing post:** 1
**Author:** ![hannes](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/hannes/32/2302_2.png) [@hannes](https://discuss.ocaml.org/u/hannes)\ **Post date:** [June 30, 2021, 3:46pm UTC](https://discuss.ocaml.org/t/ann-u2f-universal-second-factor/8078/1 "2021-06-30T15:46:44Z")
Hello, it is our pleasure to announce the just released opam package u2f, which is a server side implementation of the FIDO standard for two-factor authentication using a special device (yubikey etc.). The device does challenge-response authentication with the server using public key cryptography. The implementation is stateless and does not use a specific IO library, but only achieves the logic for constructing a registration request, verifying a response thereof, and authorization requests with responses thereof. Please have a look at [GitHub - roburio/u2f: U2F (FIDO Universal 2nd Factor) in OCaml](https://github.com/roburio/u2f) if you’re interested. It is licensed under the permissive 2-clause BSD license. We use this library in an example server (in the `bin` directory) that uses dream. The live server is online at [https://u2f-demo.robur.coop](https://u2f-demo.robur.coop) – please let us know if you run into any trouble, or open an issue on the GitHub repository. One question though: we’re unable to generate the documentation from the mli – already asked on discord with no result. Anyone with a better understanding of odoc etc. can take a look why `dune build @doc` outputs a nearly empty file? Thanks a lot 🙂 The development was sponsored by skolem.tech. --- _[View the full topic](https://discuss.ocaml.org/t/ann-u2f-universal-second-factor/8078)._