The security of data is a complex and ever-evolving research topic. This chapter aims to provide readers with a foundational understanding of data security. In Section 13.1, we will discuss the threats that can compromise the security of IoT device data and introduce the basic framework for data protection. Section 13.2 presents a scheme for verifying the integrity of IoT device firmware data. Section 13.3 introduces two encryption schemes - Flash Encryption and NVS Encryption - that ensure data confidentiality. Section 13.4 outlines the Secure Boot scheme, which safeguards the legitimacy of IoT device firmware data. Finally, Section 13.5 examines the effectiveness of combining the Flash Encryption and Secure Boot schemes and provides guidance on how to enable these schemes in device mass production.