Hash-based Digital Signatures- A tutorial review

There has been great interest currently in investigating various techniques for realizing public key encryption as well digital signatures. A promising techniques for digital signatures use well-investigated secure Hash functions. The state of the art has evolved from Lamport’s pioneering work of one tie signatures today’s few time signatures as well as stateless signatures. IETF has two RFCs on Extended Merkle signature system (XMSS) and Leighton-Micali Signature system (LMS). NIST competition on Post-Quantum Cryptography for KEM (Key Encapsulation Module) and digital signatures in the third round has considered SPHINCS+ as a potential candidate. In this tutorial paper, we describe from basics the digital signatures based on hash functions and trace the efforts made in hardware implementations as well.