Cryptanalysis of Harn digital multisignaturescheme withdistinguished signing authorities
Zuoqing Li, Lijie Hui, K. P. Chow, C.F. Chong, W.W. Tsang, Hsiu‐Wen Chan · Electronics Letters · 2000
An insider attack on Harn's digital multisignature scheme with undistinguished signing authorities is presented. In this attack, any malicious insider attacker without any secret keys of the other signers can forge a valid multisignature for any message. The insider attack cannot be detected by an outsider or verifier. In other words, Harn multisignature is insecure.