All over the Internet you see things that say MD5, SHA-1, or even CRC. All of that jibber-jabber is in reference to hash values which verify the integrity of a download. Basically, if I wanted to send you a file I would calculate one of those values, send you the file, and then you would calculate the value for the same type of hash that I used. If it matches the value that I calculated then the odds are pretty good that there wasn’t a problem with the file transfer.
How do you go about calculating these values? I have no idea why Windows doesn’t have some sort of right-click menu to do this because they could just hide it like they do with the “Command Prompt Here” for Vista. Luckily there is plenty of software that will do the grunt work for us and the few that I tested even work in Vista (despite them being several years old). Here is a rundown of the solutions I found:
digestIT (Freeware Download)
This is my favorite program for calculating and comparing hash values. It works with MD5 and SHA-1 hashes by providing a simple-to-use right-click menu for any file(s) in Windows. The reason this is my favorite is because it will not only calculate the value but you can also input a hash value and see if it matches the file’s value. That way you don’t have to sit there comparing two long strings of letters and numbers. Here is a screenshot of what digestIT looks like for the whole comparison process:
The verification feature is pretty important to me because that is primarily what I need to do. This just makes the whole process a little easier and means I have to think less…which is always a good thing. ;)
HashOnClick (Freeware Download)
This one is pretty similar to the one above except that it doesn’t have the verification option. It will only generate the hash value for you and then you’ll have to manually compare it. HashOnClick works with MD5 and SHA-1 but also does CRC hash values. Here is a screenshot of the program being used:
MD5 Column Display (Freeware Download)
This one only does MD5 hash calculations but it is unique in the way it presents itself. You don’t ever have to make an extra click to see that MD5 value because you can set it up to display a column in Windows Explorer for it. Here is what it looks like:
MD5Sum Utility (Online Calculator)
That is a site that can calculate nearly all of the different has values: haval, MD2, MD4, MD5, ripemd128, ripemd160, SHA, SHA-160, SHA-256, SHA-384, SHA-512, tiger, and whirlpool. So why wouldn’t you use this? The first reason is that you have to upload the file to their site in order for it to calculate the hash value. It is required (for logical reasons) that the PC doing the calculation has the file on the computer…which brings up another point. If you are having to upload the file to them there is no guarantee that there wasn’t an error in that process. Therefore the file that you have on your PC might be completely intact but when you upload it there is an error which results in a miscalculated hash value. Online hash generators are convenient but not something you should completely trust.
There are all kinds of ways to calculate the hash values but hopefully you’ll find one of those alternatives to work well. There is also a Firefox extension, called MDHashTool, that hasn’t been updated in years that can do the verification of the hash values all from within the browser…but you won’t be able to install the extension in a version of Firefox greater than 1.0.6 without overriding the extension compatibility check. For some reason I thought that Opera had this feature built-into their transfer manager but I looked all over and couldn’t find it. If you have a better/easier alternative for doing this please let me know!
Nogg3r5 pointed out in the comments below that HashTab is also a great solution. It will put the MD5, SHA-1, and CRC comparison features in the properties tab of every file.