## XMSS reference code

This repository contains the reference implementation that accompanies the Internet Draft _"XMSS: Extended Hash-Based Signatures"_, [`draft-irtf-cfrg-xmss-hash-based-signatures`](https://datatracker.ietf.org/doc/draft-irtf-cfrg-xmss-hash-based-signatures/).

This reference implementation supports all parameter sets as defined in the Draft at run-time (specified by prefixing the public and private keys with a 32-bit `oid`). Implementations that want to use compile-time parameter sets can remove the `struct xmss_params` function parameter.

_While the behavior of the code in this repository is supposed to be stable, the API is not yet fully complete. In particular, the wrapper for run-time parameters does not yet support the back-end functions that make use of BDS traversal (TODO). We will also add more extensive test functionality, making it easier to compare to other XMSS implementations (TODO)._

_When using the current code base, please be careful, expect changes and watch this document for further documentation._

### Dependencies

For the SHA-2 hash functions (i.e. SHA-256 and SHA-512), we rely on OpenSSL. Make sure to install the OpenSSL development headers. On Debian-based systems, this is achieved by installing the OpenSSL development package `libssl-dev`.

### License

This reference implementation was written by Andreas Hülsing and Joost Rijneveld. All included code is available under the CC0 1.0 Universal Public Domain Dedication.

## XMSS reference code

This repository contains the reference implementation that accompanies the Internet Draft _"XMSS: Extended Hash-Based Signatures"_, [`draft-irtf-cfrg-xmss-hash-based-signatures`](https://datatracker.ietf.org/doc/draft-irtf-cfrg-xmss-hash-based-signatures/).

This reference implementation supports all parameter sets as defined in the Draft at run-time (specified by prefixing the public and private keys with a 32-bit `oid`). Implementations that want to use compile-time parameter sets can remove the `struct xmss_params` function parameter.

_While the behavior of the code in this repository is supposed to be stable, the API is not yet fully complete. **In particular, the wrapper for run-time parameters does not yet support the back-end functions that make use of BDS traversal. This means that the `xmss_core_fast.c` back-end is somewhat hard to use. This is the most immediate open TODO, and will be resolved soon.**_

_When using the current code base, please be careful, expect changes and watch this document for further documentation._

### Dependencies

For the SHA-2 hash functions (i.e. SHA-256 and SHA-512), we rely on OpenSSL. Make sure to install the OpenSSL development headers. On Debian-based systems, this is achieved by installing the OpenSSL development package `libssl-dev`.

### License

This reference implementation was written by Andreas Hülsing and Joost Rijneveld. All included code is available under the CC0 1.0 Universal Public Domain Dedication.

Clarify current BDS traversal support
Clarify current BDS traversal support
