 Hey guys, welcome back to my YouTube channel. This is Daniel Rosal here I want to talk today about the scintillating topic of checksums in Ubuntu and Linux, but this actually goes way beyond Ubuntu This is I use throughout computing, but the reason that I'm interested in checksums is because For backups, which is certainly a big interest. I've been doing a lot of videos about backups Checksums are super super important. The reason for that is that but checksums are exactly let me just jump to Definition here checksum is a small-sized block of data i.e. It's just a little string little alphanumeric string, but it's derived from another block of digital data And this uses an algorithm and it's for the purpose of detecting errors that may be introduced during its transmission or Storage so two distinct use cases there by themselves checksums are often used to verify data Integrity but are not relied upon to verify data authenticity. That stuff is actually super super important Let me just try break it down a little bit. Those two use cases firstly data storage I've talked in all my backup videos about cold storage recently in mDisks about the The menace of bit rot and data rot that basically if you store a file cold in a lot of media The file will basically end up becoming corrupted and then unreadable because to take hard drives for example there'll be depolarization and So there is checksums are a great way what you can calculate a checksum on the running original file you store Let's call it just for the for the sake of simplicity file a dot text So you calculate a checksum using one of these algorithms and that checksum is a unique series of letters and numbers That verifies that this was the when we created this file. This was a checksum. This is when it was not corrupt Right, we know that this was a good state Then let's say we want to create two backups of a dot text so we can look at their checksums and that and if all is good They should be the same if there's problems the checksums will be different and that's one way of detecting data Data rot now it says here as well introduced by transmission, so this is kind of referring to stuff like, you know and people are putting a Copies of files on the internet and sometimes they get corrupted in that process. This is another way so when you're downloading Linux distros, right? You'll typically see The download link and then a checksum link and I'd say most people including me up to very recently Never went into the checksum link the checksum link as you can see has a alphanumeric string and then it's got the file name So I've downloaded this file. I chose Puppy Linux. So it would be a quick quick download Now if you're in a bunch of there's two Checksum programs that you should be that I think are good to be aware of one is called quick hash GUI And then we also have if I can still find it Yes, we have a chat to five six now in Linux. You'll typically find a Cli a command line tool and a graphic interface Everyone has their own philosophy after many many years of using Linux. I love the power of CLIs, but if there is a GUI a GUI for a solution, I will just go with the GUI, but this is the CLI the Slee, I don't know Slee. Maybe as called chat to five six some it's super easy Once you've installed it, you just type the program and then the file that you want to run the checksum against And then you'll get your checksum And the cross-platform tool is quick hash So quick hash is also available for windows and Macs. So let me show you how Quick hash will do its business. I'm just gonna pop it open here so here's quick hash and Let's say that I want to I Want to put in my file. So I'll click on file and I'm gonna select my download from amongst all my recent thumbnails and whatever I've been working on And it is the Foss here we go the ISO file So you can see it takes a few seconds to run and then what we've got here and I'm highlighting it That's the checksum, right? So you can do this for any file doesn't need to be a bunch to download It can be a word document. It can be a it can be a video in fact Etc. Okay, and you can even use this to compare two files file a and file B Let's just stick with this, right? So we got our checksum here and what you're supposed to do. Whoops that I'm gonna have to clear that. Ah, okay. It's just on my clipboard six a four five e seven eight three sixty five b Seven d thirty one seventy two ebd nine e eight five c a four sixty e four and I'm sure there's some clever way of doing this You know manually, but that looks fine to me if I just zoom in I'm gonna make that big and then I look here and you can see six a four five e seven a thirty five b seventy three one seventy two ebd ebd nine e a b five c a Four six zero e four. That's perfect. So those checksums are exactly aligned And that's basically how you can use checksums in a bunch to Verify not just the case of downloading, you know installation programs off the internet You can also use them to compare a original backup with a Subsequent backup copy and very very useful thing to know how to do