Authentication / Integrity Processes
Authentication of digital files is the process by which information is assured to be what it appears or claims to be. One method used to verify that a file has not changed over time is to create and verify checksums on a regular schedule.
A checksum is a unique number that is generated by running an algorithm against a file. If any part of the file changes, the original checksum value would no longer match demonstrating that the file is no longer authentic.
Tools that can assist in this process include:
- DROID: A multipurpose tool that can generate MD5 checksum values on files it is run against. The main purpose of DROID is to identify file formats and capture other file property information. Guides have been written by the Minnesota State Archives, the University of Hull, and the University of Minnesota Libraries.
- Exact File: A Windows based program that can create and verify checksums on individual files as well as files in a nested set of folders. Multiple checksum algorithms are available to use. The University of Minnesota Libraries has written a guide on how to use this program to create and verify checksums.
- Fixity: Developed by AVPreserve, this tool creates MD5 or SHA-256 checksums for files in chosen directories (up to seven). The tool then monitors file integrity through validation of checksums on a set schedule (determined by you). Generated reports document file validation; they also document if a file is new, missing, moved, or renamed. Reports can be emailed to up to seven individuals. AVPreserve has created an video tutorial as well as a user guide. The tool itself can be found here.
- Hash My Files: A Windows based program that calculates multiple checksum algorithms as well as captures file property information. Hash My Files also has the capability to identify duplicate file formats. The Minnesota State Archives and the University of Minnesota Libraries wrote a review and guide of this program.