Hypericum: a post-quantum digital signature for standardization in Russia

In this work we describe Hypericum: a stateless hash-based digital signature scheme proposed for standardization in Russia. Hypericum is a post-quantum signature scheme based on meta-schemes SPHINCS \(^+\) ${}^{+}$ and SPHINCS \(^+\) ${}^{+}$ C. In the paper we describe the various adjustments and modifications considered during the development of the Hypericum scheme. Our modification covers the instantiations of hash function, new address compression and parameters evaluation.