The Trusted Execution Environment (TEE) is a secure area of a processor. The TEE provides security features such as isolated execution, integrity of Trusted Applications along with confidentiality of their assets. In general terms, the TEE offers an execution space that provides a higher level of security than a "rich" operating system and more functionality than a secure element. For example, implementations of the TEE concept have been developed by ARM, and Intel using the TrustZone and the SGX technology, respectively. To programmatically install, update, and delete applications in a TEE, this protocol runs between a service within the TEE, a relay application or service access point on the device's network stack and a server-side infrastructure that interacts with and optionally maintains the applications. Some tasks are security sensitive and the server side requires information about the device characteristics in the form of attestation and the device-side may require information about the server. Privacy considerations have to be taken into account with authentication features and attestation. This working group aims to develop an application layer protocol providing TEEs with a lifecycle management of trusted applications and security domain management. A security domain allows a service provider's applications to be isolated so that one security domain cannot be influenced by another, unless it exposes an API to allow it. The solution approach must take a wide range of TEE and relevant technologies into account and will focus on the use of public key cryptography. The group will produce the following deliverables. The first draft is an architecture document describing the involved entities, their relationships, assumptions, the keying framework and relevant use cases. Second, a solution document that describes the above-described functionality will be developed. The choice of encoding format(s) will be decided in the working group. The group may document several attestation technologies considering the different hardware capabilities, performance, privacy, and operational properties. The group will maintain a close relationship with the IETF SUIT working group, GlobalPlatform, Trusted Computing Group, and other relevant standards to ensure proper use of existing TEE-relevant application layer interfaces.