Disclosed is a trusted language runtime (TLR) architecture that provides abstractions for developing a runtime for executing trusted applications or portions thereof securely on a mobile device (e.g., a smartphone). TLR offers at least two abstractions to mobile developers: a trustbox and a trustlet. The trustbox is a runtime environment that offers code and data integrity, and confidentiality. Code and data running inside a trustbox cannot be read or modified by any code running outside the trustbox. A trustlet is the code portion of an application that runs inside a trustbox. With TLR, programmers can write applications in .NET and specify which parts of the application handle sensitive data, and thus, run inside the trustbox. With the TLR, the developer places these parts in a trustlet class, and the TLR provides all support needed to run the parts in the trustbox.