The Secure Electronic Transaction (SET) protocol has been proposed by a consortium of credit card companies and software corporations to guarantee the authenticity of e-commerce transactions and the confidentiality of data. When the customer makes a purchase, the SET dual signature keeps his account details secret from the merchant and his choice of goods secret from the bank. This paper describes Java implementation of a Dual Signature and then illustrates the working of signature with the help of GUI made in Java Net Beans 7.0.