The best method of verifying if the integrity of a file has not been affected is to calculate its hash values and compare them to previously-specified ones. Calculating their hash values (also known as “check sums”) is also a reliable method of comparing files. HashTab is a very neat and simple tool that provides one of the fastest and easiest ways of calculating the hash values of files, as it comes as a shell extension for your Windows system.
You may view the hash values of a file by right-clicking it, selecting “Properties” from the Windows Explorer’s context menu (the right-click menu), and then checking the “File Hashes” tab.
A really nice thing about this application is the fact that it can calculate file check sums using multiple hash algorithms, such as Adler32, CRC32, HAVAL, MD4, MD5, SHA1, SHA2, SHA256, RipeMD, Tiger and Whirlpool. You can easily choose which ones of these will be used for the hash calculation from the application's "Settings" window. Furthermore, HashTab includes a simple, neat yet handy comparison function that lets you quickly compare the hashes of two files. Last but not least, this little tool is also completely free. As you can see, it truly represents a very fast and easy manner to quickly calculate the hash values of files.