Paper 2026/022 Original: eprint.iacr.org/2026/022 ↗

FABS: Fast Attribute-Based Signatures

Abstract

Attribute-based signatures (ABS) provide fine-grained control over who can generate digital signatures and have many real-world applications. This paper presents a pair of fast ABS schemes: one for Key-Policy ABS (KP-ABS) and another for Signature-Policy ABS (SP-ABS). Both schemes support expressive policies using Monotone Span Programs (MSP), and offer practical features such as large universe, arbitrary attributes, and adaptive security. Most notably, we provide the first implementation of MSP-based ABS schemes and demonstrate that our schemes achieve the best-known asymptotic and concrete performance in this domain. Asymptotically, key generation, signing and verification time scale linearly with the number of attributes; verification requires only two pairing operations. In concrete terms, for 100 attributes, our KP-ABS scheme performs key generation, signing, and verification in 0.16s, 0.10s, and 0.13s, respectively; our SP-ABS scheme achieves times of 0.082s, 0.26s, and 0.21s for the same operations.