Hey everybody welcome to the next video.
So in this video we're going to briefly go over the difference between lossless and lossy.
Now what is a lossy compression.
This is a compression which may or may not be lost during one's compressed so there might be some bits
of data that are changed damaged or modified entirely or just missing.
Now this is very bad for things like executable is where one bit being changed depending on where it's
change can either cause the application to not run not be built correctly in the memory it could break
a lot of things in for text files as an example.
You want to have all the text intact so when you go to sift through the logs you don't have some random
bits of data missing but lossy does have its uses.
It's used for graphics videos and images where one or two bits changing doesn't affect the whole structure.
So the graphics and images relatively the same losing one or two bits isn't going to change the image
you would have to go down a bit bit by bit level to under to see a change in the image.
But in most cases one or two bits across the whole image you're never going to see the difference.
Same thing with the video.
It might be one frame one bit in one frame of a ten minute video that might have gotten changed doesn't
affect the video it just means that that one bit is gonna be a different color than what it was expected
to be so is that noticeable.
Not really.
So in this in these particular cases a lossy compression or lossy type of compression is not a bad idea.
It's quick but dirty at the same time.
So just understand where its uses are now a lossless compression is the exact opposite.
We don't where we want data to be in the exact original state that we had it in before we compressed
it.
This is perfect for executable text spreadsheets.
Anything that we want the data to be exactly the same.
There's no room for error.
So this is not a quick and dirty.
This is just a quick sometimes not so much quick depends on what you're doing and how much you're compressing
and what you're compressing.
However know that you don't lose any data with this because it can change the functionality of everything's
like I that executable using one or two bits in the wrong places.
Means the whole thing doesn't work.
Go ahead and open up on our windows machine.
Grab a copy of an executable copy it onto the desktop open it and a notepad.
Change one value in there save it and then try to run.
Chances are I'm gonna break or not gonna do anything or Windows is gonna throw an error saying it can't
load it or anything like that.
Now some of the common lossless algorithms that we're going to go over in this video is LV 77 and LCD
78 again lossless tends to be used for logs and it's the most common compression that you're going to
see on a daily basis from a red team's perspective.