Patent attributes
Files essential to the boot sequence are validated as they are executed. As core boot files are loaded and executed by a computers a hash of the files is created and extended into configuration registers. Core operating system files are verified by the boot loader using a digital signature, and the public key used to verify the digital signature is recorded in a configuration register. Core operating system files verified by the boot loader include a list of hash values, which is used by the operating system to validate the other files as they are executed. User assurance that the system has booted correctly is achieved by comparing the state of configuration registers to previously stored values reflecting the expected state of the registers. Upon the state of the configuration registers matching what is expected, data previously selected by the user is retrieved and recognized by the user.
