Patent ID: 7805765

Claim:
A machine-implemented method, comprising: performing a validation check and creating a file signature for each execution process associated with a computer file; wherein said file signature comprises a header, a message authentication code, a hash value, a hash value time stamp corresponding to the time that the hash value was created, and a write time stamp corresponding to the time the validation check was completed; and wherein the header includes the results of the validation check; during a subsequent validation operation performed by the validation program on the computer file, comparing the hash value time stamp with the write time stamp; comparing the previously-created file signature with a validation signature during said validation operation in response to the write time stamp matching the hash value time stamp within a predetermined criterion and determining if the computer file is invalid or valid based on the comparison of the previously-created file signature with the validation signature; creating a new hash value and updating the previously-created file signature to include the new hash value only in response to the write time stamp not matching the hash value time stamp within the predetermined criterion, and retaining the hash value in the previously-created file signature only in response to the write time stamp matching the hash value time stamp within the predetermined criterion; and comparing the updated file signature with the validation signature during the validation operation in response to the write time stamp not matching the hash value time stamp within the predetermined criterion, and determining if the computer file is invalid or valid based on the comparison of the updated file signature with the validation signature.