Digital signatures represent one of the most widely used security technologies for ensuring unforgeability and non-repudiation of digital data. The digital signature technique is generally used for validating or authenticating digital information. This paper presents two hardware ECDSA methods: synchronous and GALS based designs. A reduced power dissipation of hardware Elliptic Curve Digital Signature Algorithm (ECDSA) design has been developed. This ECDSA method can be used for low power computing. The authors’ proposed architecture is based on the Globally Asynchronous Locally Synchronous (GALSs) design methodology. In GALS system, modules that are not used frequently can be made to consume less power by pausing their local clocks until they are needed. Their design consists of using units that are clocked independently.