A method and apparatus for high assurance boot processing is disclosed. A trusted processor is used to authenticate a trusted boot program and in conjunction with a selector, to provide the authenticated boot program to a boot memory where it can be accessed by a main processor to execute the bootup sequence. The trusted processor also provides a command for the main processor to write a data sequence to a hard drive or similar device, and monitors the data written by the main processor to verify that the data has not been tampered with or otherwise compromised.