In accordance with certain aspects, a chain of trust is established between a subscriber unit and a content provider. A request is submitted from the subscriber unit to the content provider. A challenge nonce is generated at the content provider and returned to the subscriber unit. At the subscriber unit, an operating system (OS) certificate containing an identity of the operating system from the software identity register, information describing the operating system, the challenge nonce, and a CPU public key is formed, and the OS certificate is signed using a CPU private key. The OS certificate and a CPU manufacturer certificate supplied by a manufacturer of the CPU are passed from the subscriber unit to the content provider, and are evaluated at the content provider to determine whether to reject or fulfill the request.