In an anonymous credential system, when a credential has been shown for verification, none can identify the owner of the credential and link the relationship between any two credentials. The unlinkability is the crucial feature for any anonymous credential system. In 2002, Jan Camenisch and Anna Lysyanskaya proposed a signature scheme (CL signature) which allows users to demonstrate their credentials without revealing their identity information. However, CL signature is compounded of a lot of zero-knowledge proof technologies which cause inefficiency for CL signatures. Such heavy computation requirements may limit the scope which CL signatures can be applied to. In this thesis, we propose a new blind signature scheme based on ElGamal signatures and design an anonymous verification procedure which is more efficient than the CL signature scheme. Finally, we also implement our proposed protocols.