Abstract
A (t, n) threshold proxy signature scheme allows t or more proxy signers from a designated group of n proxy signers to sign messages on behalf of an original signer. The authors review both Zhang's threshold proxy signature scheme and Kim's threshold proxy signature scheme. They show that Zhang's scheme suffers from some weaknesses and Kim's scheme suffers from a disadvantage. Based on Zhang's scheme, they propose a new threshold proxy signature scheme to defeat the weaknesses of Zhang's scheme and the disadvantage of Kim's scheme.