A decades old and still working method for verifying the integrity of files is by comparing their checksums. A checksum or hash of a file is a calculated value using hashing algorithms such as MD5. If the content of the files change, their hashes also change. This way we can check whether the integrity of files have been compromised.
There are many tools for calculating the hash values using a number of hashing algorithms such as MD5, SHA1, RIPEMD and more. But if you want to create and later check the hashes of a number of files simultaneously then you can use EF Checksum Manager.
It is available in both installer and portable format. It has a user interface that looks similar to the File Explorer. We can navigate to any drive or folder through this interface. When we have opened a folder under which we want to calculate the checksums, we can select all the files/folders and then click on the Create Checksum icon in the toolbar.
It presents with a new window from where we can choose whether there should be just one file for all the hashes or a separate file for all the file hashes. We can also choose to recurse the sub-folders. It uses MD5 as the hash algorithm by default but we can choose CRC32, SHA1, SHA224, SHA256, SHA384, SHA512, SHA-3 224, SHA-3 256, SHA-3 384, SHA-3 512 etc.
Once you have created the checksum files, you can verify the integrity of these files by launching EF Checksum Manager, navigating to that folder and clicking on the Verify Checksums icon in the toolbar. The results of the verification will be shown in a smaller window. You can export these results to a file if needed.
EF Checksum Manager is a great way to ensure that none of your files have been modified in any way. It is able to create and verify the file checksums for a large number of files in a few seconds.
You can download EF Checksum Manager from http://www.efsoftware.com/cm/e.htm.