A new standard signature algorithm named "HSS/LMS" has been introduced. The HSS/LMS algorithm is defined in [RFC 8554: Leighton-Micali Hash-Based Signatures and NIST Special Publication 800-208](https://www.rfc-editor.org/rfc/rfc8554). New `KeyFactory` and `Signature` implementations are available for the algorithm. The `KeyFactory` only operates on public keys and the `Signature` only covers the verification part.