US Patent 7805765 Execution validation using header containing validation data

Executable files are extended with a file signature containing a header containing validation data. This header may be added to an existing executable and linking format (ELF) header, added as a new section, or placed in a file's extended attribute store. The header contains results of all previous validation checks that have been performed. The file signature is inserted, with a date stamp, into the file attributes. On execution, the system checks the previously-created file signature against a current file signature, instead of creating the file signature for every file during the execution process. Checks to ensure that the file signature is secure, and is valid and up to date, are also implemented. Only if the file signature is not valid and up-to-date does the execution program create a new file signature at the time of execution.