In today's computer
network environments
we're using two major
methods of encrypting data.
We have symmetric encryption
and asymmetric encryption.
Symmetric encryption
is a method where
we are using
exactly the same key
to encrypt information and
decrypt the information.
They're both using exactly
the same information.
So we know that if we
need to encrypt data,
and somebody on the other
side needs to decrypt it,
we need to somehow get that
key to them so that they
will be able to
decrypt that data.
And because it is exactly the
same information on both sides,
it's the same key on both sides,
you have to keep it secret.
If somebody was to get that
key somewhere in the middle,
they would be able to look
at all of the information
that we had encrypted.
They'd be able to
see everything.
And that means if the key
gets out, or if it's lost
or if it's stolen,
you're going to need
to create another secret
key and get that secret key
to the person who
will be receiving
the information that we're
sending out in encrypted form.
So obviously this
doesn't scale very well.
If you give a secret
key to one person,
you might think that that key's
going to be relatively safe.
What if you give that
secret key to 100 people?
Is that key still
going to remain safe?
And since you have
to have that key
to be able to decrypt
the information,
anybody can get their hands
on it and look at information.
Now we've got a bit of a
security challenge ahead of us.
Even so, we are still
using symmetric encryption
in many ways today, and that's
because symmetric encryption
is so fast to use.
It uses so few resources
when you compare it
to asymmetric encryption.
Because of that, you'll
often see these combined.
You'll see asymmetric
encryption combined
with symmetric encryption, to be
able to have not only a secure
environment where
data is protected,
but also have one
that works very,
very quickly and very,
very efficiently.
The other type of encryption
that you'll commonly see
is asymmetric encryption.
You'll also hear this referred
to as public key cryptography,
and you'll understand
why in just a moment.
This type of encryption
method has really only
been around since the 1970s.
So in the world
of encryption it's
a relatively new
capability, and it
has allowed us to do
quite a number of things
in our technologies.
There are two keys needed
in asymmetric encryption.
If you recall, in
symmetric encryption
you had exactly the same key.
But in asymmetric encryption,
as the name implies,
you have two keys.
You have a private key,
and this private key
is something as also
this name implies you,
want to keep private.
Nobody gets their hands on the
private key except for you.
You would not share this
private key with someone else.
You would not give
it to someone else.
Nobody else needs
this private key.
The key that you're going
to give to everyone else
is one called a public key.
Give it to everybody.
Put it on a public server.
Post it on your website.
Stick it on your Facebook page.
Everybody should have
access to this public key.
Nobody but you should have
access to the private key,
and that's because
the public key is
one that allows people
to send you information
in an encrypted form,
but the private key
is the only key that
can decrypt that data.
And that makes this a
very interesting method
of storing and
encrypting information,
because if somebody
was to encrypt data
with your public key, they
would not be able to decrypt it.
Nobody would be
able to decrypt it.
Even if somebody got their hands
on it somewhere along the way,
the only way to decrypt it
is with that private key,
and that's why it
is so important
to keep that key private.
Not only is it
private, we usually
will put a pass phrase
associated with it.
We make sure that that
key is very, very secure
and nobody gets
their hands on it.
And in that way you
can be relatively
public with the information
that you're sending.
You don't have to worry about
it so much because nobody could
take that encrypted data and
use your public key in some way
to decrypt it.
It doesn't work that way.
You have to have the private
key to decrypt that information.
So you can see, using this
asymmetric encryption really
gives us some new ways of
encrypting data, keeping
that data safe, and making
sure that nobody can get
their hands on that information.
And when you combine
asymmetric encryption
with the symmetric
encryption, you really
have a lot of
flexibility with how
you're going to encrypt the
data, send it to someone else,
and be able to decrypt
it on the other side.
