Owing to the ubiquitous nature, ease of deployment, and wide range of potential applications, wireless sensor networks (WSNs) have received a lot of attention recently. WSNs can be deployed in unattended environments; however, they have many challenges. It should be guaranteed that not only illegitimate users cannot login and access data in the network but also user privacy should be maintained. Since sensor nodes have limited computation power, storage, and energy, it is desirable for the authentication protocol to be simple and secure. In this paper, we propose two user authentication protocols that are variations of a recent strong-password-based solution. It uses one-way hash functions and XOR operations to achieve lower computational and communication overheads. We have analyzed the performance of both the proposed authentication schemes in terms of various metrics. We have also provided security evaluation of the proposed protocols. Comparing with the previous schemes, our proposed schemes are more robust and provide better security.