The first incorruption that we'll learn how to rake is called Then you epee or Wired Equivalent Privacy.
This is an all day encryption that can be easily broken.
The reason why I'm still covering it in this chorus is first of all because like I said it's very simple
Also it's a good starting point also.
It's still used sometimes in some networks.
Therefore you can't really call yourself a hacker and then if you see a network that uses Web you'll
get stuck and you won't even be able to break into it.
So in this lecture I'm going to explain how web works and what's the weakness that we can use to break
it.
And in the next lecture you'll see how we can use this weakness in order to break web and get the key
for any network that uses them.
Epee So basically there's a new epee uses an algorithm called oracy for to encrypt its data so the way
this works is basically if a client wanted to send something to their outer and let's say it was to
send this text they are sent to the rafter it'll first encrypt this using a key.
Therefore this normal text will be converted into gibberish as you can see here.
This encrypted packet will be sent into the air.
So for heico captures this packet as we seen before if we opened this packet we'll see that it's full
of gibberish even though it actually contains useful information we want to be able to read it because
it's encrypted.
The access point will they receive this encrypted packet it'll be able to transform it back to its original
form because it has the key.
Therefore it'll actually be able to read the contents which is that at the centre of the rafter.
The same happens if the rafter was to send something back to the client at first encrypted use in a
key send it to the client.
The client will be able to decrypt it because it has the key.
So the concept is always the same.
The transmitter encrypted data using a key sends it to the receiver.
The receiver is able to decrypt it because it also has the key.
Therefore anybody who captures the packet in the middle they will get the packet but they want to be
able to see the contents because they do not have the key.
So the algorithm and the way or issue for works is actually fine.
The problem is with the way that W epee implement this algorithm and to understand this let's zoom in
a little bit more on each step.
So go back to the first step.
We have the client tried to send data to the router and the data that it wants to send is that to send
to the outer.
So in order to encrypt this new epee tries to generate a unique key for each packet so literally each
package that's sent into the air it tries to create any you unique key forehead.
To do that it generates a random 24 bit initialization vector the initialization vector is then added
to the password of the network to the actual key that people use to connect to the network.
This generates a key stream and then this key stream is used to encrypt this backward and transform
it in to gibberish.
So basically we have the key stream Plus the data that we need to encrypt gives us the gibberish and
then the gibberish is sent into the air.
But before sending this into the air.
W E P will also append the initialization vector.
This is the 24 bit random number that I said it creates in order to make sure that each packet has a
unique key.
The reason why it is the initialization vector to the packet is because once the writer receives this
packet it needs to be able to decrypted and to decrypt it.
It needs the key and the i.v.
What they're after already has the key So there is no need to send that.
Therefore we just need to send it the ivy.
So when the writer receives the packet it has the Ivy it has the password or the key so it can generate
a key stream and then use that key stream to transform this gibberish into its original form and read
the packet.
So if you think about why I said you can probably guess what the weakness is.
Basically the I.V. is sent in plain text so if you look at this you can see the packet content is encrypted.
So if someone captures this packet they won't be able to read this but they will be able to read the
i.v in plain text.
Also the size of the i.v is only 24 bits.
No considering the huge amount of traffic that can be generated on a wife network.
This number is not big enough and the ivie's will start getting repeated in a busy network.
This makes them.
Epee vulnerable to statistical attacks so we can use a tool called aircraft engine to determine the
key stream.
Once we have enough repeated ivie's and from that it'll also be able to crack w epee and give us the
key to the network.