Registered Attribute-Based Signature

This paper introduces the notion of registered attribute-based signature (registered ABS). Distinctly different from classical attribute-based signature (ABS), registered ABS allows any user to generate their own public/secret key pair and register it with the system. The key curator is critical to keep the system flowing, which is a fully transparent entity that does not retain secrets. Our results can be summarized as follows. Technically, our registered ABS is inspired by the blueprint of Okamoto and Takashima [PKC'11]. We convert the prime-order registered attribute-based encryption (registered ABE) scheme of Zhu et al. [ASIACRYPT'23] via predicate encoding to registered ABS by employing the technique of re-randomization with specialized delegation, while we employ the different dual-system method considering the property of registration. Prior to our work, the work of solving the key-escrow issue was presented by Okamoto and Takashima [PKC'13] while their work considered the weak adversary in the random oracle model.