Fuzzy Signature from Computational Diffie–Hellman Assumption in the Standard Model

Fuzzy signature (SIGF) is a type of digital signature that preserves the core functionalities of traditional signatures, while accommodating variations and non-uniformity in the signing key. This property enables the direct use of high-entropy fuzzy data, such as biometric information, as the signing key. In this paper, we define the m-existentially unforgeable under chosen message attack (m-EUF-CMA∗) security of fuzzy signature. Furthermore, we propose a generic construction of fuzzy signature, which is composed of a homomorphic secure sketch (SS) with an error-recoverable property, a homomorphic average-case strong extractor (Ext), and a homomorphic and key-shift* secure signature scheme (SIG). By instantiating the foundational components, we present a m-EUF-CMA∗ secure fuzzy signature instantiation based on the Computational Diffie–Hellman (CDH) assumption over bilinear groups in the standard model.