Files downloaded or sent over the Internet are always prone to corruption. This necessitates the checking of their integrity should such files provide their original information or work as intended. Most softwares are “self-checking” in that they will fail to execute indicating corruption.
Some files however have to be verified manually. The most common way to do this involves verifying a hash or checksum compiled from the original file that users can check against their files using a program. Microsoft unfortunately doesn’t include an essential function such as this in Windows.
Consequently, plenty of hash-checking programs exist however most don’t integrate into Windows Explorer in a convenient way that doesn’t demand constant launching. Lucky for us, we have two free ones can do just this.
Calculate and Verify Checksums using HashCheck
The first program is the free and open source HashCheck Shell Extension that is compatible with Windows XP and later. HashCheck weighs a paltry 85kb and works straight from the Window’s shell.
After you install it, the program will add a Tab called Checksums in the Properties Dialog of all files which you launch by right-clicking on a file then going to Properties.
|HashCheck Checksum Tab|
Every time you switch to Checksums tab the program will automatically calculate 4 types of checksums that include: CRC-32, MD4, MD5 and SHA-1. MD5 is typically what’s used by most across the web.
To verify you only need to paste the correct checksum (it doesn’t matter which type) in the text box and then hit the find button. If it finds a match, it will highlight it for you meaning the file will have passed the integrity test.
|HashCheck in Properties Window|
If you’re the publisher or the one sharing a file you can also easily create a checksum file using the same program. That option is automatically installed in the context menu. To create a checksum file, just right-click on the file, select Create Checksum File and in the Save dialog window select the checksum format you want and then Save.
|Creating Checksum File from the Context Menu|
After that, you only need to package the file together with the checksum file or provide it separately. If the recipient has this program installed they only have to double click the checksum and the program will do the rest by calculating and verifying the hashes.
If they don’t have the program, the checksum file is basically in plain text and as such can be opened by any text editor. From there they can get the checksum which they can proceed to verify with their program of choice.
If you don’t require this feature, you can easily remove this item from the context menu by turning it off by clicking the Options button found in the Checksums tab.
Compare Hashes of Two Files using HashTab
In certain cases you may want to compare two files to confirm if they’re exactly the same or are different. For that you may use HashTab from Implbits.
The software works in the same exact way as HashCheck only that it adds an option to compare two files against each other as well as offering.
|HashTab in Properties Window|
It doesn’t really matter which you should use, just pick what works best for you best. Both are freeware but HashTab is closed source and can only be used for personal use, students and for non-profit. So for commercial purposes I take it just stick to HashCheck.