Cryptology ePrint Archive: Report 2017/279

Post-Quantum Zero-Knowledge and Signatures from Symmetric-Key Primitives

Melissa Chase and David Derler and Steven Goldfeder and Claudio Orlandi and Sebastian Ramacher and Christian Rechberger and Daniel Slamanig and Greg Zaverucha

Abstract: We propose a new class of post-quantum digital signature schemes that: (a) derive their security entirely from the security of symmetric-key primitives, believed to be quantum-secure, and (b) have extremely small keypairs, and, (c) are highly parameterizable.

In our signature constructions, the public key is an image y = f(x) of a one-way function f and secret key x. A signature is a non-interactive zero-knowledge proof of x, that incorporates a message to be signed. For this proof, we leverage recent progress of Giacomelli et al. (USENIX'16) in constructing an efficient Sigma-protocol for statements over general circuits. We improve this Sigma-protocol to reduce proof sizes by a factor of two, at no additional computational cost. While this is of independent interest as it yields more compact proofs for any circuit, it also decreases our signature sizes.

We consider two possibilities to make the proof non-interactive: the Fiat-Shamir transform and Unruh's transform (EUROCRYPT'12, '15,'16). The former has smaller signatures, while the latter has a security analysis in the quantum-accessible random oracle model. By customizing Unruh's transform to our application, the overhead is reduced to 1.6x when compared to the Fiat-Shamir transform, which does not have a rigorous post-quantum security analysis.

We implement and benchmark both approaches and explore the possible choice of f, taking advantage of the recent trend to strive for practical symmetric ciphers with a particularly low number of multiplications and end up using LowMC (EUROCRYPT'15).

Category / Keywords: public-key cryptography / post-quantum cryptography, zero-knowledge, signatures, block cipher, Fiat-Shamir, Unruh, implementation

Original Publication (with minor differences): ACM CCS'17

Date: received 27 Mar 2017, last revised 22 Mar 2018

Contact author: sebastian ramacher at iaik tugraz at

Available format(s): PDF | BibTeX Citation

Note: The performance figures presented here are somewhat outdated. For up to date figures see This paper is a merge of ePrint:2016/1085 and ePrint:2016/1110.

Version: 20180322:154234 (All versions of this report)

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