Attack on a concast signature scheme

Security Analysis of Concast and Anycast Digital Signature

“…Stinson [5] proposed a forgery attack where any user can forge a signature that could be validated and verified. Given a message, anyone can easily perform this attack.…”

Group Testing and Batch Verification

“…History shows that secure batch verification algorithms are tricky to construct; a number of schemes were presented and subsequently broken or shown to be otherwise flawed. One example is the scheme of Al-Ibrahim et al [1], which was broken by Stinson in [39]. Camenisch et al list and reference ten proposed schemes which were later broken [8, §1.2].…”