Hey everybody welcome to the next video.
So in this video we're gonna going Oh we're gonna be going over symmetric encryption.
Now what is symmetric encryption.
It uses the same cryptographic key for encryption and decryption.
Now this is a very important concept that I if anything you take out of this particular video is that
symmetric encryption or any algorithm that uses symmetric based encryption uses the same key for encryption
as well as decryption.
That is a very important concept here.
Now in normal cases this key is shared between two or more parties so they can encrypt and decrypt messages
that they send back and forth.
Now what are some of the drawbacks.
Every party member in the conversation will have the same key if one gets compromised they're all compromised
and that is a problem whereas asymmetric only one key one key depending on which key gets compromised
Popeye's the whole thing.
Or it might not compromise it at all.
So it's important to understand this concept.
Now this symmetric encryption uses pseudo random generators and this is used for generating the keys
that are never used.
Now the problem with this is there isn't a thing is true random at the moment and in some cases when
certain applications use symmetric based encryption there generation of the keys they're pseudo random
key generators aren't using enough random or they use the same seed as an example so they use the same
base value to generate their keys and stuff like that is how attacks have happened in the past.
On symmetric encryption algorithms now there are two different types of symmetric algorithms or symmetric
encryption.
There are stream ciphers and block ciphers.
What you're going to be most familiar with and what you're going to be mostly seeing in the real world
is block ciphers.
How Roman a touch on stream ciphers now stream ciphers will encrypts digits letters etc. One at a time
in a string.
So it goes in a row goes through the whole block of data and encrypts everything one at a time.
This is also used in substitution based cryptos as well.
And the opposite of that is a block cipher.
So blocks ciphers use a set number of bits such as 60 for 128 or 248.
They use a certain amount of bits and encrypt them all as one entity.
So you're not encrypting one digit or value at a time or one character at a time you're encrypting a
whole block at a time.
Again just a quick note on block ciphers if the plain text does not fit the amount of space.
So if you if you're trying to do you have an algorithm that's using a 64 bit block cipher as a symmetric
encryption you're going to end use like a four digit code as an example.
It will pad in the rest of the data with different data to make sure that it meets the required length.
Now some of the common ones that you'll see using symmetric encryption is a s three D s and RC four.
Now in this particular course we're going to be going over briefly on a yes in 3D.
Yes.
So that's it for symmetric encryption.
Again just keep in mind that it uses the same key for encryption and decryption.
So in the next video we're going to be going over is asymmetric encryption.