Embodiments of the present invention disclose a method and system for protecting the security of encrypted software. Specifically, the present invention pertains to a method of decrypting only those steps or portions of the software that are written to a processor's internal instruction cache. While in storage in non-volatile memory and in RAM, encrypted software remains in an encrypted state. The invention includes a decryption unit that may be located internal to the processor and performs decryption of the software as it enters the instruction cache. By use of this method, encrypted software is resistant to copying from RAM in a decrypted state for subsequent reverse engineering. Software that is protected by this method could be any intellectual property meant to processed by computer that is delivered to the user by internet, cable, direct satellite, packaged media, or any other means.