Cryptology ePrint Archive: Report 2012/213

Relation between Verifiable Random Functions and Convertible Undeniable Signatures, and New Constructions

Kaoru Kurosawa and Ryo Nojima and Le Trieu Phong

Abstract: Verifiable random functions (VRF) and selectively-convertible undeniable signature (SCUS) schemes were proposed independently in the literature. In this paper, we observe that they are tightly related. This directly yields several deterministic SCUS schemes based on existing VRF constructions. In addition, we create a new probabilistic SCUS scheme, which is very compact. The confirmation and disavowal protocols of these SCUS are efficient, and can be run either sequentially, concurrently, or arbitrarily. These protocols are based on what we call zero-knowledge protocols for generalized DDH and non-DDH, which are of independent interest.

Category / Keywords: public-key cryptography / Selectively convertible undeniable signatures, verifiable random function, standard model

Date: received 18 Apr 2012

Contact author: letrieu letrieuphong at gmail com

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Version: 20120422:224404 (All versions of this report)

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