Security Analysis of the Unrestricted Identity-Based Aggregate Signature Scheme
This work is incremental as it exposes vulnerabilities in a specific cryptographic scheme, impacting researchers and practitioners in identity-based cryptography and digital security.
The paper identifies an efficient forgery attack and a serious flaw in the security proof of a recent identity-based aggregate signature scheme proposed by Yuan et al., which aimed to solve the open problem of constructing a secure IBAS scheme with full aggregation in bilinear maps.
Aggregate signatures allow anyone to combine different signatures signed by different signers on different messages into a single short signature. An ideal aggregate signature scheme is an identity-based aggregate signature (IBAS) scheme that supports full aggregation since it can reduce the total transmitted data by using an identity string as a public key and anyone can freely aggregate different signatures. Constructing a secure IBAS scheme that supports full aggregation in bilinear maps is an important open problem. Recently, Yuan {\it et al.} proposed an IBAS scheme with full aggregation in bilinear maps and claimed its security in the random oracle model under the computational Diffie-Hellman assumption. In this paper, we show that there exists an efficient forgery attacker on their IBAS scheme and their security proof has a serious flaw.