We've talked a lot about symmetric and asymmetric algorithms
already and how they work
but we haven't really about
the specific asymmetric algorithms yet.
So in this lesson,
we're going to cover the three asymmetric algorithms
that you have to know for the security plus exam.
They are Diffie-Hellman, RSA and the ECC
or Elliptic curve cryptography.
The first asymmetric algorithm we're going to talk about
is known as Diffie-Hellman.
Diffie-Hellman is named for it's two inventors.
The Diffie-Hellman algorithm is used
to conduct key exchanges and secure key distribution.
It's used widely when you're setting up VPN tunnels
and other encryption tunnels,
that require asymmetric algorithm's shared secret key
that private key, to be exchanged first
before setting up that symmetric tunnel
and by using this asymmetric Diffie-Hellman,
we can do that.
Diffie-Hellman is susceptible to
man in the middle attacks though,
so, if you want to secure it you need to make sure you have
some form of authentication,
such as requiring a password,
or a digital certificate,
at the beginning of the exchange process.
When you see Diffie-Hellman on the exam,
I want you to remember two big things.
First, it's an asymmetric algorithm
and second it's used for the key exchange inside of
creating a VPN tunnel establishment as part of IPSec.
Our second asymmetric algorithm is known as RSA.
It's also named for it's creators,
Ron Rivest, Adi Shamir and Leonard Adleman.
RSA is widely used for key exchange,
encryption and digital signatures.
The algorithm relies on the difficulty of
mathematically factoring large prime numbers
and this protects its public and private key pairs.
RSA can support key sizes between 1024-bits and 4096-bits.
RSA is widely used in organizations around the globe,
if you happen to have one of those secure tokens
on your key chain, where every 30 to 60 seconds
the six digit number changes
and you use that as part of your log in
and multi factor authentication,
well guess what?
You're using RSA!
Because that token stores RSA asymmetric one time use keys.
When we cover PKI in depth
in the next section of this course,
you can be assured that I'm going to be discussing,
all of the ins and outs of how RSA is used
to secure our networks.
The final type of asymmetric algorithm
that we're going to cover in this section is known as ECC,
or Elliptic Curve Cryptography.
ECC is heavily used in mobile devices
and it's based on the algebraic structure
of elliptical curves over finite fields to define its keys.
ECC is very efficient and provides better security
than an equivalent RSA key of the same size.
In fact, ECC's algorithm is six times more efficient
than an RSA algorithm.
So if you're going to have a 256-bit key with ECC,
you'd require a 2048-bit key with RSA to be just as secure.
For this reason, you're going to see ECC
used in a lot of things like tablets, smartphones
and other mobile based implementations
because these devices have much less processing power
available than does a standard desktop or laptop.
There are a few variations of ECC as well
and you might come across these in the field.
The first is ECDH,
which is the Elliptic Curve Diffie-Hellman.
Which you might have guessed
is an ECC version of our popular,
Diffie-Hellman key exchange protocol.
Another variant is known as the ECDHE
which is the,
Elliptic Curve Diffie-Hellman Ephemeral protocol.
Which uses a different key for each portion
of the key establishment process
inside, the Diffie-Hellman key exchange.
The final one you might come across,
is known as the ECDSA, which is the
Elliptic Curve Digital Signature Algorithm
which is used as a public key encryption algorithm
by the US Government in their digital signatures,
for the exam remember that ECC
and all of it's variants are most commonly used
for mobile devices and low-power computing devices
because it gives you equivalent protection
to other asymmetric algorithms with a lower key size.