A method of boot-loading an electronic device. The method comprises boot-loading a trusted execution environment (TEE) in a trusted security zone of a processor of the electronic device, where the TEE boot-loads before a rich execution environment (REE) boot-loads, launching a boot-loader authentication application by the TEE in the trusted security zone, determining a signature value of an REE boot-loader by the boot-loader authentication application over the instructions of the REE boot-loader, comparing the signature value of the REE boot-loader to an authentication signature value stored in the TEE, and, in response to the signature value of the REE boot-loader not matching the authentication signature value, taking action by the boot-loader authentication application.