CA Mandatory APIs

Table 1 describes the mapping between the mandatory CA and TA APIs.

**Table 1** Mandatory APIs for CAs
Function Name	Description
TEEC_InitializeContext	Initializes a TEE context to establish a connection between the CA and TEE.
TEEC_FinalizeContext	Releases a TEE context to break the connection between the CA and TEE.
TEEC_OpenSession	Opens a session. After a CA calls this function, the secure OS calls the TA_OpenSessionEntryPoint function of the corresponding TA, or the TA_CreateEntryPoint function if a TA instance has not been created.
TEEC_InvokeTACommand	Uses the session and command ID to notify the specified TA of performing the operation matching the command ID.
TEEC_CloseSession	Closes a session. After a CA calls this function, the secure OS calls the TA_CloseSessionEntryPoint function of the corresponding TA. If the session that the CA closes is the last session of the TA, the secure OS calls the TA_DestroyEntryPoint function to delete the TA instance.

Parent topic: Communication Between a CA and a TA