The presenting invention relates to techniques for implementing a secure operating environment for the execution of applications on a computing devices (e.g., a mobile phone). In The secure operating environment may provide a trusted environment with dedicated computing resources to manage security and integrity of processing and data for the applications. The applications may be provided with a variety of security services and/or functions to meet different levels of security demanded by an application. The secure operating environment may include a security engine that enumerates and/or determines the security capabilities of the secure operating environment and the computing device, e.g., the hardware, the software, and/or the firmware of the computing device. The security engine may provide security services desired by applications by choosing from the security capabilities that are supported by the secure operating environment and the computing device.