File checksums are calculates using special one-way encryption algorithms like SHA-1, MD5 or CRC which give a unique checksum value for a particular file. If you change even a single byte of that file, its file checksum value will be changed completely. This is why checksums can be used to verify the integrity of files – to know whether they have been modified or not.
File checksums are also called hashes and can be calculated easily in Windows using a third-party application like HashOnClick. It is a freeware program that integrates well in Windows File Explorer. After the installation of HashOnClick in Windows, you can right-click on any file or a group of files and choose to calculate the file hashes. There is a choice of three algorithms – MD5, CRC and SHA-1. Even though all of these hashing algorithms are now considered insecure, they are also very fast.
It displays a window where it will add all the files that you have selected in a list and continue to calculate their file hashes. If any files have a matching file hash, they will be displayed with an equal sign next to them. If you have copied a file hash to the clipboard prior to calculating the hashes, it attempts to find a matching file hash and informs you if it finds any. From the list of hashes, you can choose to save them to a file or copy them to the clipboard.
HashOnClick is a small but fast file checksum calculator and comparison tool. Using this tool, you can calculate file hashes for any file in Windows. It automatically compares the file hash in the clipboard with the ones it has calculated and display the matches if any. It can be used to find identical files from a group of files or folders.
You can download HashOnClick from https://www.2brightsparks.com/freeware/index.html.