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MD5 checksumming: use it!

Posted: Sun May 03, 2020 3:27 pm
by Brutman
I'm not too sure if everybody knows about this technique, but it is great for detecting changes to files or corruption.

The short story: when you archive a disk or create something that you want to make sure doesn't change remember to generate an md5 checksum for the file(s) and store those in a text file with the files. That way you can come along later, rerun the md5 checksums, and compare it to the original ones that you generated. If the checksums are the same then nothing has changed. (Probably, but the odds are infinitesimally low of a hash collision.)

Concrete example: When I archive diskettes I create a diskette image that is a standard, 360KB raw sector dump of the diskette. I then use the md5 program on the image file to generate a checksum, which I store in md5sums.txt along with the disk image file. If I transfer the file to another machine or just want to verify that it hasn't been changed or corrupted I re-run md5 and compare the original result to the new result.

I just added an md5 program that runs on the Jr to . Under Linux it is called md5sum, and Windows implementions exist too.