File checksums are a special string of letters and numerals that are calculate.d using hash algorithms such as MD5, SHA1, SHA2, etc. These are essentially one-way encryption algorithms which means we can create the checksum string from the original data but we cannot create the data from the checksum. These checksums also called hashes are unique for the original source data. This is why checksums are used to check the integrity of the source data. We can use third party tools like DoubleCommander for calculating the file checksums.
Double Commander is a dual pane file manager for various platforms. It comes packed with many useful tools and one of them is to calculate the checksums of files, create the checksum files and verify the checksums later on. Here is how we can calculate the file checksums using the DoubleCommander:
- First of all download and install DoubleCommander on your computer from https://doublecmd.sourceforge.io/. It is available for various platforms such as Linux, Windows and FreeBSD.
- Launch DoubleCommander and in its explorer, select the files for which you want to calculate the checksums.
- From the menubar select Files and then Calculate Checksums.
- You will see a small window from where you can select the algorithm for the checksum. You can create a checkum file that contains checkums for all the select files or create a separate checksum file for each of these files. After selected the file hashing algorithm, you can click on the OK button.
- In the background, it will calculate the checksums and write them inside a checksum file. In our example, it created a file doublecmd.exe.sha256 which contains the SHA-256 hash for the file doublecmd.exe.
These hash files can be shared together with the original files inside an archive so that the end user can use them to verify the checksums. For verification of the checksums, we can use the DoubleCommander once again. The verification tool is available from the Files menubar just like the Checksums function is.