All programs that offer the functionality work alike. They process a list of files, create checksums for each file and save those information to a list. The verification then takes place when the program is run again on the same set of files. Files that have not been modified in the meantime have the same checksum, modified files a different one.

I have reviewed several file verification programs in the past. This includes File Verifier++ and SVF Ninja as well as HashTab a Windows Explorer shell extension and the command line tool Checksum Integrity Verifier.

Checksum Control is a portable file verifier for the Windows operating system. Its portable nature makes it ideal for verification of backups on optical discs or external storage devices. Just create a file verification table of all files that you want to backup and put that list along with the Checksum Control program in the backup location.

The actual checksum creation process is straightforward. Selevted SFV/MD-5 Create from the task list when the program starts. You can then add files or folders via drag and drop, or by selecting a root folder for the creation. The application supports a skiplist which basically is a blacklist of files that will not be included in the checksum creation process.

Checksum Creation supports two types of checksums, SFV checksum files and MD-5 checksums. The latter are better suited for file verification purposes as it uses larger checksum values.

You select a file name for the verification file in the last step and may add a comment to the file as well. This completes the creation of the file verification table.

You select the file verification option on the start page if you want to verify a previously created file verification table. The program will check all file checksums and display a report to in the end. The report window displays files with correct and wrong checksums, as well as files that have been skipped during the test.

How does it compare against previously reviewed file verification programs? File Verifier++ supports additional algorithms and has the easier to use interface and the same is true for SVF Ninja. Checksum Control is a great alternative even though it takes longer to create the file verification table thanks to the applications paged layout.

Windows users can download Checksum Control from the developer website. The application is compatible with 32-bit and 64-bit editions of the Windows operating system.

But file integrity can be important on the local PC as well. A program like Exact File can tell you exactly if someone modified your Word or Excel document, or played your game just a little bit further.

Exact File is a free file integrity tool for the Windows operating system. It can process single files or batch process complete folders. The software supports all important hash methods including MD5, SHA512, CRC32 and about a dozen more.

Options to create checksums for single or multiple files, as well as to verify the integrity of already checked files are offered in the program’s interface.

A single-file check works by dragging and dropping a file into the interface, or selecting it in the file browser. ExactFile will compute all supported hashes and display a report in the end listing them all.

The generated information can be copied to the clipboard. More interesting is the ability to create a digest. A digest contains hash values of all files found in a selected folder and its subfolders.

It is again possible to drag and drop a folder into the program window, or to use the file browser to pick a folder from the system. Available options are to include subfolders, full paths in the output and to out the checksums to a file.

All supported hash methods are available, but only one can be selected for the process.

ExactFile will process all files in the selected folder structure and display a similar results window in the end.

The calculations are speedy and use all available cpu cores by default. The results are stored in the selected file and displayed to the user directly. It is here again possible to copy them to the clipboard.

The test digest menu is available to test a previously generated folder hash. All it takes is to select the digest file, click verbose report and then go to compare the previously generated hash values of the files with the current ones.

One interesting application for this would be to generate the hashes before sending the files to another user. The receiving user could then test the validity of the files by running the previously generated checksum file against the received files.

An option to create a test file applet is available to make this easier. Instead of having to use the file integrity software to check the files, it is possible to generate and use a standalone executable generated by the program to do the same. Ideal for putting it on burned CDs or DVDs, or sending it along with the files for the recipient to check.

Exact File is a sophisticated file verification tool for the Windows operating system. Especially the option to test and verify the integrity of all files in a folder is welcome, coupled with the option to create a standalone executable to verify the integrity at all times.

What the developer of Exact File says:

• A file integrity verification tool:

  Use it to make sure files copied to CD-ROM are bit-perfect copies,
  Use it to make sure backups copied from one drive to another are just right,
  Use it to make sure files haven’t been changed or damaged over time.

• Multi-threaded, so your extra CPU cores get used when scanning multiple files and work gets done faster.
• Happy with Unicode file names, so it doesn’t fail when you’re using it on files named in Japanese, Hebrew, Chinese, or any other language.
• Supports multiple checksum routines (hashes), like MD5, SHA1, CRC32, RIPEMD and others.
• Supports recursive directory scanning.
• Supports Very Big Files — If it’s on your hard drive, ExactFile can handle it.
• Does everything popular file summer utilities do, like fsum, md5sum, sha1sum, sfv, etc, but better!
• Compatible with popular file checksum digest formats.
• For Windows 2000, XP, and Vista.
• GUI. Easy to use to get checksums for individual files, create checksum digests, and test checksum digests. Does not require the console version or any external DLLs.

Interested users can download Exactfile from the developer homepage. The program is compatible with most 32-bit and 64-bit editions of the Windows operating system.

Let me first explain why it could be important to check the hash algorithm of downloaded files. Many software developers and download portals add hash information to their downloads. Those information clearly identify a file and the user can compare the hash of a downloaded file with the hash on a website to make sure that he got that file and that no one tampered with it in the meantime.

It obviously makes only sense if the hash information are published on the website that contains the download. MD5 Hasher makes use of the Firefox Download Manager which means that the downloads have to appear in there because it is currently the only way to check the hash of the file.

MD5 Hasher can check a variety of hash algorithms including MD5, SHA1 and SHA512. Just make sure you pick the right one when comparing the checksums. A right-click on a downloaded file and the selection of Check Digest opens the MD5 Hasher window that provides access to the checksum comparison.

It’s not as comfortable as it could be because of several reasons. A direct link to the functions of the add-on would be nice. It would also be great if the hashes would be displayed automatically and if previous downloads could be processed as well.