1. A system for secure execution of processor instructions, the system comprising: a first memory configured to store an encrypted instruction; and a secure processor system coupled to said first memory and configured to receive the encrypted instruction, said secure processor system comprising: a processor, and a security controller configured to decrypt said encrypted instruction according to a decryption algorithm, wherein the decryption algorithm uses a first key as a key input to the decryption algorithm and an address corresponding to a location in said first memory of said encrypted instruction as an initialization vector input to the decryption algorithm.