SOTS: A Hash Function-Based Shorter Post-Quantum Digital Signature Scheme

In the post-quantum digital signature schemes, the Hash-based signature schemes are efficient and provably secure. However, one major drawback of Hash-based signature schemes is the large size of the key and the signature. In this study, based on existing digital signature schemes, a new One-Time Signature (OTS) scheme, which reduces both the number of the signatures and the size of each signature, has been proposed. Under the same post-quantum security level, the proposed scheme reduces the key and the signature sizes by 77% and 82.0% respectively as compared with the Winternitz OTS scheme. And it also reduces the key and the signature sizes by 60.7% and 60.5% respectively as compared with WOTS+. In terms of the signature size, compared with the NOTS, SDS-OTS and WOTS-S schemes proposed in the past two years, this proposed novel scheme has reduced by 17%, 24.5% and 48.1% respectively. Furthermore, this novel scheme is existentially unforgeable under the Chosen-Plaintext Attack (CPA) model. The security of this scheme is a security reduction of the onewayness of the underlying Hash function. Moreover, compared with WOTS+, the proposed signature scheme reduces the time of generating keys, creating signatures and verifying signatures by 71.4%, 47.7%, and 60.9% respectively.