Blind signatures are fundamental cryptographic primitives enabling privacy-preserving authentication and have seen renewed interest in the post-quantum literature. Existing efficient constructions predominantly rely on Fischlin’s generic paradigm instantiated over lattice assumptions, while blinding techniques for Σ-protocol-based blind signatures remain sparse beyond lattices. Moreover, achieving provable concurrent security under polynomially many sessions has been a longstanding open challenge for this approach in the post-quantum literature as evidenced by the recent attacks in EC’24 and PKC’24. This work broadens the landscape of post-quantum blind signatures by introducing novel techniques and proposing four frameworks based on general cryptographic group actions, without requiring commutativity. Our constructions admit instantiations under diverse post-quantum assumptions, including CSIDH (isogeny-based), LESS (code-based, NIST round-two), and more. These frameworks offer flexible trade-offs in assumptions (from interactive one-more to the standard inversion problem) and key/signature sizes, and culminate in a construction that achieves security under polynomially many concurrent sessions. This enables the first efficient blind signatures from isogenies and codes with provable concurrent security with 4.5 and 64.7 KB respectively. We also outline several directions for optimization and further instantiations for future work.
The high pace of quantum computing development presents a serious risk to classical cryptographic systems like RSA and ECC in that quantum-resilient communication systems must be developed. The present paper will suggest Quantum Blind Signature-based Hybrid Quantum Key Distribution (QKD -QBS) to provide secure and authenticated quantum communication. The proposed architecture uses both BB84 and Decoy-State QKD protocols with Quantum Blind Signature (QBS) authentication layer in order to support quantum key generation and verification of entities in the same session. The framework is simulated and tested with IBM Qiskit Aer simulator in realistic channel noise situations. Quantum Bit Error Rate (QBER), Secret Key Retention (SKR), Quantum Entropy (H), Authentication Latency and Security Index (SI) are used as performance evaluation metrics. The experimental data show that the QBER is low (0.34%), SKR is high (92.4%), entropy is nearly ideal (
H=0.99) with the lowest authentication latency (0.17 ms), which proves the fact that the integration of QBS does not reduce the efficiency of the key generation but the reliability of authentication. The hybrid framework proposed has information-theoretic security using the principles of quantum mechanics and strong resistance to impersonation, re-play and man in the middle attacks. The findings show that QKDQBS model provides a scalable and solid platform of next generation secure communication systems, such as IoT,
5G/6Gnetworks, and cloud-based quantum systems.
We study the design of practical blind signatures in the universal composability (UC) setting against adaptive adversaries. We introduce a new property for blind signature schemes that is fundamental for managing adaptive adversaries: an equivocal blind signature is a blind signature protocol where a simulator can construct the internal state of the client so that it matches a simulated transcript even after a signature was released. We present a general construction methodology for building practical adaptively secure blind signatures: the starting point is a 2-move “lite blind signature”, a lightweight 2-party signature protocol that we formalize and implement both generically as well as number theoretically: formalizing a primitive as “lite ” means that the adversary is required to show all private tapes of adversarially controlled parties; this enables us to conveniently separate zero-knowledge (ZK) related security requirements from the remaining security properties in the primitive’s design methodology. We then focus on the exact ZK requirements for building blind signatures. To this effect, we formalize two special ZK ideal functionalities, single-verifier-ZK (SVZK) and single-prover-ZK (SPZK) and we investigate the requirements for realizing them in a commit-and-prove fashion as building blocks for adaptively secure UC blind signatures. SVZK can be realized without relying on a multi-session UC commitment; as