Web Service Security (WSS) provides message level protection between two ends of clients and web services. This work proposes a WSS architecture whose security will be based on Data Encryption Standard (DES). It models a web service security based on DES, and evaluates the performance of the WSS using some standard metrics. To enable evaluation of the system, experiments were conducted in a Windows Vista Operating System environment using relevant tools. The evaluation result revealed that, deploying security alongside web services comes with additional overheads like Extra Central Processing Unit (XCPU) Time Cost for the message that is encrypted and to be transmitted, the server CPU Time to Process Request with Encryption (SCTPWE) increases along with the Request/Respond Time with Encryption (TRRWE), the Server CPU Time to Process Request with Encryption (SCTPWE) is greater than the Server CPU Time to Process Request without Encryption (SCTPWOE).