The TEE is an insulated and secure area of the main processor providing security functionality for application integrity and confidentiality. The TEE differentiates between security functionality and operational functionality. It mainly consists of three parts: Trusted OS, internal micro-kernel, and APIs. Used for security check parallel to standard OS. Common security functions include isolated execution of security operations, the integrity of code loaded and data stored and confidentiality of data stored in the TEE. It protects data-at-rest and data-in-use within the TEE. It also provides higher performance and access to a large amount of memory.