When downloading a large file — like an ISO file of a Linux distribution — and the download process is done, you need to make sure whether the file you downloaded is corrupted or not. The vast majority of Linux ISO file providers provide MD5 checksum for each ISO file which you can use to validate the downloaded ISO file.

If you use Windows, you don’t need to install additional app to validate a file integrity as Windows has a built-in tool do so. The tool is certutil. Certutil a command-line tool that becomes a part of the Certificate Services.

How to use certutil to validate a file integrity in Windows

Before validating your file integrity using MD5 algorithm, you need to make sure that the website where you downloaded the file from provides the MD5 checksum file. The content of this file is a line of random characters, something like encryption code. Some websites (like FileHippo), provide the MD5 checksum on the description page instead of a file. This is doesn’t matter, as long as you can copy it.

Here is how to validate the file integrity using MD5 in Windows.

• Copy the MD5 checksum of the file you want to validate to Notepad or your favorite text editor.
• Launch Command Prompt and navigate to the location of the file you want to validate using cd command. For instance, if the file is located in the Downloads folder then you should type cd Downloads

• Type certutil -hashfile followed by the file name and MD5.

• Check the generated code and compare it with the MD5 checksum on your Notepad and make sure they both are match.

If you find that code doesn’t match with the MD5 checksum then the file is not valid.