Forgery attacks on two identity based signature schemes
Peng Xu · Journal of Communications · 2013
Li Ji-Guo et al.proposed an identity based signature scheme in the standard model in 2009,and a similar scheme was proposed by Gu Ke et al.in 2011.Three algorithms were constructed to attack these two schemes.In these attacks,attacker could forge a valid signature on any message on behalf of any user in polynomial time only by choosing random parameters without knowing the signing key of the user.The attacks showed that their signature schemes were insecure.The root causes of attacks were further analyzed and some possible improvements were given in the end.