By way of example only, in various embodiments, the present system and system is designed to reduce the size of data on a computer through compression, to improve hash, message digest, and checksum technology and their application to information and data storage, to improve uniqueness by using mutual exclusion in hash and checksum tests, to improve checksum tests providing better computer security, to create an XML compression format and to move binary compression formats to XML or other markup language, to utilize variable length hashes and message digests, and to create an XML based checksum that can be used to verify the integrity of files.