ID-based cryptosystems have several advantages over the traditional PKC (Public Key Cryptosystems), but how to obtain the private key anonymously from them is still an open problem. Sui et al. proposed an ID-based key issuing protocol addressed the anonymity issue recently. But in their scheme, the one time password must be strictly protected, and any adversary can pass the identity verification by replacing the legal user?s authentication parameters. An improved key issuing scheme is proposed to remove these limitations in this paper. Compared with Sui et al.?s scheme, the new scheme has illustrated higher security and better efficiency, and preserves all the other advantages of the original one. An extension of our scheme to remove key escrow problem is also presented.