The electronic cash (or e-cash) technology based on the foundational work of Chaum [7] is emerging as a scalability and privacy layer atop of expensive and traceable blockchain-based currencies. Unlike trustless blockchains, e-cash designs inherently rely on a trusted party with full control over the currency supply. Since this trusted component cannot be eliminated from the system, we aim to minimize the trust it requires.

Threshold signatures are becoming an increasingly popular method of signing key protection, primarily due to their ability to produce signatures that require the cooperation of multiple parties yet appear indistinguishable from a regular signature. This unique feature allows for their easy integration with existing systems, making them highly desirable in applications like national identity systems and transaction authorization, where they are being gradually deployed; their growing importance is further attested by NIST’s recently initiated efforts to standardize threshold schemes [19].

19th International Conference on Security and Cryptography (SECRYPT), Lisbon, PORTUGAL, JUL 11-13, 2022