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WinMD5Sum - checking to make sure you have a good copy

Posted by ClifNotes, Oct 2008, permalink tag20tag|tagtagtag


Recently I read an article in Terry's Computer Tips newsletter that I'd like to pass on. He covers the ideas behind MD5 checksums and offers a review of a nice freeware that helps you use them. I can heartily recommend signing up for Terry's newsletters. They don't take long to read and you'll often learn something new.


I use MD5 at work fairly often. I use it to verify copies of files that I archive using an Excel worksheet. I wrote a macro that moves the files and then calls the md5sums command line tool which gives me a log of the MD5 checksums.


You may not need a tool to give you an MD5 checksum, but at least you'll know what these are if you keep reading.


Review from Terry:

Program: WinMD5Sum

Publisher: Nullriver Software, www.nullriver.com

Category: Utility to verify integrity of download

License: Short, custom user-friendly license

Price: Freeware


First, I need to explain what MD5 is. MD5 is a hashing algorithm (a number-crunching method) that is designed to read every byte of a file and generate a long, unique code based on its contents. md5Sum is a program in the Linux world that is used to generate verification codes for software files.


The most important features of an MD5 sum are that: (1) it is easy to use and (2) if a single character/byte changes in the file, the MD5 sum is dramatically different.


md5sum is often used when Linux programs are made available for downloading. Since most of the programs are open-source and free, and anyone can distribute them, the publisher often uses md5Sum to create the unique identifying sequence of characters for the file. That way, you can download from anywhere, but still use md5sum on your own computer to calculate the MD5 sum verification code, and compare it to the MD5 sum published by the originating site.


Tech Tip

By the way, the MD5 sum for the downloadable proggram Install-winMd5Sum.exe is 7d2b88b560095b9a59576fc75cdb1ef5.


So, what is WinMD5Sum? You guessed it — a Windows program to calculate an MD5 sum.


Sometimes, Windows programs are distributed with MD5Sums, or Linux programs may be downloaded to a Windows computer. By using WinMD5Sum, we can calculate the MD5 sum to make sure that we downloaded an unmodified file and also confirm that there was not a bad download.


What do I use it for? I often will download a Linux distribution in the ISO image format, so I can burn a CD of it. WinMD5Sum allows me to make sure that the file is the same as the original and that the download process did not corrupt the file (which sometimes happens).


What else does WinMD5Sum do? Nothing.


Terry Stockdale



Get WinMD5Sum