Hybrid Cryptographic Protocols Providing Digital Signature

Yerzhan N. Seitkulov, R. M. Ospanov, B. B. Yergaliyeva +2 more

One of the modern directions in the field of information security is post-quantum cryptography. Its purpose is to develop new quantum-resistant cryptographic algorithms. An important section of post-quantum cryptography is electronic digital signature algorithms. There are a number of different approaches to designing post-quantum signatures. One of the main approaches to designing post-quantum cryptographic digital signature algorithms is hash-based post-quantum digital signature schemes. Hash-based post-quantum digital signature schemes are one of the main types of post-quantum cryptographic digital signature algorithms. They are quite efficient and provably secure. Their reliable security has been established against both classical and quantum attacks. There are many types of digital signatures for solving various information security problems, such as group signatures, ring signatures, blind signatures, verifiably encrypted signatures, etc. This paper proposes a new cryptographic protocol of verifiably encrypted signature with possibility of verification after a specified time based on the post-quantum cryptographic algorithm of hash-based digital signature, TANBA-SPHINCS+. The protocol is an efficient combination of the postquantum digital signature algorithm TANBA-SPHINCS+, the cryptographic protocol providing data encryption for a specified time, ECTLC, and the verifiably encrypted signature scheme.

Dinh Duc Nha Nguyen, Dang Hung Duong, Phi Long Nguyen

The rise of quantum computing poses significant risks to classical cryptographic algorithms, especially those used in digital signatures within Virtual Private Networks (VPNs). This paper proposes a hybrid cryptographic framework for IPsec VPNs that combines traditional digital signatures with post-quantum cryptographic (PQC) techniques to enhance security against both conventional and quantum threats. Our method introduces a dual-signature scheme integrated into the IKEv2 protocol, verified using formal methods via the Tamarin Prover to ensure robustness. We further evaluate performance using a modified StrongSwan implementation under realistic network conditions. Results show that while hybrid signatures introduce modest overhead, they provide a viable and forward-compatible solution for securing VPNs in the post-quantum era.

Hans Delfs, Helmut Knebl

Hans Delfs, Helmut Knebl

Shijun Yu

In order to meet the challenges brought by quantum computing, research on post-quantum cryptography has been carried out comprehensively. Among them, the most influential one is the post-quantum cryptography algorithm standardization project initiated by NIST. In July 2022, NIST announced that the Dilithium, Falcon, and SPHINCS+ algorithms were selected as candidate schemes for the standardization of post-quantum cryptographic digital signatures. The OQS project team is committed to promoting the transition of existing security protocols to standardized post-quantum algorithms and is currently the mainstream open-source post-quantum project. This paper improves the post-quantum hybrid digital signature scheme used by the OQS project team. Firstly, the hybrid digital signature scheme used in this project is studied, and it is found that there are security risks. Subsequently, an enhanced scheme is constructed and implemented using the hybrid algorithm combiner proposed by Nina Bindel et al., solving the security issues. The unforgeability and 2 -non-separability of the enhanced scheme are verified through formal analysis, and forward compatibility is achieved. The enhanced scheme shows obvious advantages in key generation efficiency and signature verification efficiency. Under some algorithms, the speed of signature verification of the improved scheme is 60 % of the original scheme. Meanwhile, the enhanced scheme also demonstrates stability in terms of time and storage overhead. Finally, the TLS1.3 protocol PSK mechanism is implemented using the enhanced scheme. This is the first implementation of post-quantum algorithm security protection in the PSK mechanism of the TLS protocol. This scheme can resist man-in-the-middle attacks while meeting the requirements of forward compatibility.