This repository contains the SPHINCS-256 reference code, modified to use SHAKE256 as a hash function rather than the BLAKE and ChaCha-based construction as originally proposed. All other parameters and constructions are kept the same. This positions it somewhere between SPHINCS-256 and the recent SPHINCS+ submission to NIST's post-quantum cryptography project.
The SPHINCS-256 code was placed in the public domain as per Section 1 of the SPHINCS paper. The FIPS202 code was placed in the public domain as part of the Keccak Code Package. All other modifications are available under the CC0 1.0 Universal Public Domain Dedication.