In the last lesson he discussed that cell and TLS create a tunnel which protects your data so you can
transfer it securely.
But what does that actually mean?
What must be done to data in order to consider it protected?
That's what we'll be discussing in this lesson.
Here are two users.
These users can be referred to as a client and a server, but we'll provide more formal definitions
for the term clients and server later on in this module.
This blue user or the client wants to send a message securely to the green user or the server.
The problem is that anything sent on a wire can be captured by anybody in the middle.
So if the blue user sends this message, this red user can easily capture the message while it's in
transit.
This is what SSL and TLS are trying to protect you from.
But contrary to popular belief, as tiles cannot prevent the capture of data.
Once data is on the wire, it is in somebody else's hands.
Instead, the purpose of SSL TLS are to protect what can be captured on the wire, and it'll do so in
three ways.
First, it will provide confidentiality to that data.
Confidentiality means that the data should only be accessible by the client and the server.
Meaning on the wire it should be encrypted.
So if someone in the middle captures it, they won't be able to make sense of what they captured.
Next S.E.A.L.s are going to provide integrity to that data.
And what that does is it makes it so that data cannot be modified between the client and the server.
Now, to be clear, it doesn't actually prevent the modification of data, but it does enable detection
if the data was modified.
It's one thing to not be able to understand what is sent on the wire because of confidentiality.
But it's another thing entirely to not be able to change what was sent on the wire with integrity.
If this read user modifies some of the text in this message.
The green user will be able to detect it and know that that message has been tampered with.
Finally, the last thing that SSL and TLS will do to data is going to validate the authentication of
that data, meaning they're going to make sure that the client and the server are indeed who they say
they are.
SSL TLS will do this by validating the identities of the two parties in communication.
So these three items are the main purposes of cell and TLS, and each of these are provided via different
cryptographic functions.
Confidentiality is provided via encryption, integrity is provided via hashing, and authentication
is provided via the public key infrastructure.
And to truly understand SSL and TLS, we must first discuss the cryptographic tools which make SSL until
as possible.
In the next module, we'll be picking apart encryption, hashing and the public key infrastructure and
showing you how those tools will provide confidentiality, integrity and authentication.
Before I close this lesson, there is one more idea I want to leave you with.
Notice, at no point in our discussion did we mention that there was a tunnel between the client and
the server.
You see, the idea behind an SSL tunnel is merely conceptual.
In reality, an actual tunnel is not literally built across the internet.
It's simply a way to visualize what SSL and TLS are doing.
To be clear, it is a useful visualization.
In fact, it is one we'll use again throughout this course.
But in reality, the data you put on the wire is still passing through someone else's network.
The only difference is with SSL and TLS, the data will be protected using confidentiality, integrity
and authentication.
Meaning if someone does capture your data, they won't be able to read it because of confidentiality.
They won't be able to modify it because of integrity, and they won't be able to pretend to be you because
of authentication.
That is what SSL and TLS are doing.
And with that said, we bring this lesson to a close.
The main takeaway is understanding the terms confidentiality, integrity and authentication.
We'll be using these terms again and again throughout this course.
So it's very important to have a very clear understanding of what each of them are and why you need
all three of them in order to consider data set to cross a wire as secure.
In the next lesson, we'll describe two other terms that are often described, along with confidentiality,
integrity and authentication.
But that's it for this lesson.
I hope you enjoy this video.
I want to thank you for watching and we'll see you in the next one.