# Common Asymmetric Algorithms

Video Activity

Join over 3 million cybersecurity professionals advancing their career

Sign up with

Required fields are marked with an *

or

Already have an account? Sign In »

Time

15 hours 43 minutes

Difficulty

Advanced

CEU/CPE

16

Video Transcription

00:00

>> Now that we've talked about

00:00

how asymmetric algorithms work,

00:00

let's talk a little bit more about some of

00:00

the specific asymmetric algorithms

00:00

and how we're going to use them.

00:00

I had mentioned earlier we'd seen

00:00

a list of the common symmetric algorithms.

00:00

Certainly, those are not

00:00

the only symmetric algorithms in the world,

00:00

and these are not the only

00:00

asymmetric algorithms in the world.

00:00

But these would be the ones that I would

00:00

expect would come up on the exam.

00:00

We have DSA, RSA,

00:00

ECC, El Gamal,

00:00

Diffie-Hellman, and Knapsack.

00:00

What I would expect you to be able to

00:00

do is to look at a list of

00:00

algorithms and pick these six

00:00

out and say those are asymmetric.

00:00

That can be tricky because they were like 10,

00:00

15 symmetric algorithms to memorize.

00:00

Here, an additional six that are asymmetric.

00:00

Let me show you just a little trick.

00:00

What I would do is I would

00:00

memorize the algorithms that are asymmetric.

00:00

If they're not asymmetric,

00:00

then they're probably symmetric.

00:00

Don't forget, you still have

00:00

to know your hashing algorithms

00:00

like MD5 and SHA1, but that's okay.

00:00

Those are Message Digest 5,

00:00

Secure Hash Algorithm, SHA1.

00:00

Those are okay, you can remember those as hashing.

00:00

But if you'll remember the list of

00:00

asymmetric algorithms and the algorithm

00:00

you're being quizzed with isn't there,

00:00

then assume it's symmetric.

00:00

The way I would remember

00:00

which algorithms are asymmetric,

00:00

and this is totally ridiculous,

00:00

but I would use the buddy system.

00:00

Here's what I mean by that.

00:00

Before you start your test,

00:00

one of the things that I would recommend you just

00:00

jotting down on a sheet of scrap paper is,

00:00

which algorithms are asymmetric?

00:00

Then again, if it's not there, it's symmetric.

00:00

To remember which algorithms are symmetric,

00:00

each algorithm has a buddy,

00:00

each algorithm has a friend.

00:00

The first two buddies are the SA brothers, RSA and DSA.

00:00

Those are your first two buddies,

00:00

RSA, DSA, SA brothers.

00:00

Your next two buddies both start with E. You

00:00

have ECC and El Gamal.

00:00

El Gamal and ECC,

00:00

they both start with E. That's my second group.

00:00

The last two asymmetric algorithms

00:00

you need to remember, are Diffie-Hellman and Knapsack.

00:00

It may seem a little odd that those two are buddies.

00:00

But Diffie-Hellman is frequently abbreviated DH.

00:00

When you see DH, it's almost

00:00

assuredly talking about the Diffie-Hellman algorithm.

00:00

An old friend of mine used to refer to

00:00

that algorithm as the Doogie Howser algorithm.

00:00

For those of you that have missed this fine piece of

00:00

quality American television programming,

00:00

Doogie Howser was a series in the,

00:00

I can't remember, '80s or '90s,

00:00

something where Neil Patrick Harris

00:00

starred as a 13-year-old brain surgeon.

00:00

His name was Doogie Howser.

00:00

I don't know which would be more offensive to

00:00

me as having a 13-year-old surgeon,

00:00

come in and introduce himself

00:00

or him telling me his name is Doogie.

00:00

I think that would be a problem also.

00:00

But anyway, so Neil Patrick Harris,

00:00

13-year-old brain surgeon's name was Doogie Howser.

00:00

At the beginning of each show,

00:00

during the opening credits,

00:00

he would come in and he would have his backpack or

00:00

his knapsack that he put into his locker.

00:00

Doogie Howser has knapsack and

00:00

that's how you remember those two are buddies.

00:00

As ridiculous as it is, just close your eyes.

00:00

Humor me. Close your eyes.

00:00

Who are my first two buddies?

00:00

They are the SA brothers,

00:00

RSA and DSA. Who are the next two?

00:00

ECC and El Gamal,

00:00

they both start with Es.

00:00

Who are my last two buddies?

00:00

You will never forget,

00:00

Doogie Howser and his knapsack,

00:00

also known as Diffie-Hellman and his Knapsack.

00:00

Now we're going to talk about what

00:00

these algorithms do because

00:00

each one has a different function, in just a second.

00:00

But for now, just being

00:00

able to put those on a sheet of paper.

00:00

Let me ask you, once you do that,

00:00

is AES symmetric or asymmetric?

00:00

Once not on this list,

00:00

it must be symmetric.

00:00

What about IDEA?

00:00

Not on this list, must be symmetric.

00:00

What about ECC? That's on this list.

00:00

That's an asymmetric algorithm.

00:00

What about Skipjack?

00:00

Symmetric. What about Blowfish?

00:00

Symmetric. What about Twofish?

00:00

Symmetric. What about Triple DES?

00:00

Symmetric. If you can just

00:00

get down on a sheet of paper

00:00

these six asymmetric algorithms,

00:00

well, then you're going to have a leg

00:00

up on questions that are

00:00

going to require you to know whether

00:00

an algorithm is symmetric or asymmetric.

00:00

If it's not in this list, then it's symmetric.

00:00

But let's just talk about a couple of these

00:00

because they have specific interest for us.

00:00

RSA is the first one that we're going to talk about.

00:00

It's named for the gentlemen

00:00

that worked together to create this algorithm.

00:00

Ron Rivest, and we have Adleman and

00:00

Shamir and they came together

00:00

to develop this algorithm called RSA.

00:00

It replaced an older algorithm called DSA,

00:00

which was the Digital Signature Algorithm.

00:00

For today,

00:00

the current standard for digital signatures is RSA.

00:00

When we talk about that piece of a digital signature,

00:00

where the hash is encrypted with

00:00

the sender's private key,

00:00

it's RSA that's providing that encryption.

00:00

Really important. RSA is your guy

00:00

>> for digital signatures.

00:00

>> The other thing that's important or

00:00

relevant to us about RSA is,

00:00

it uses a unique trap-door

00:00

>> feature called factorization.

00:00

>> The relationship between the public

00:00

>> and private keys with

00:00

>> RSA is based on the idea that

00:00

it's very easy to take

00:00

two huge prime numbers and multiply them together.

00:00

If I gave you a calculator right now,

00:00

you can take those numbers and multiply them together.

00:00

However, when you look at the result,

00:00

it is incredibly difficult to figure out what

00:00

two prime numbers were multiplied

00:00

together to get that result.

00:00

It's easy to multiply them together,

00:00

but to look at the result and

00:00

factor out the possibilities,

00:00

that is incredibly time-consuming.

00:00

That's the secret of the relationship between the keys.

00:00

The big things to remember for RSA,

00:00

digital signatures and that it uses factorization.

00:00

Diffie-Hellman, a.k.a, Doogie Howser,

00:00

is important because it was

00:00

our first asymmetric algorithm and

00:00

came out in the late '70s, I believe.

00:00

Here's the phrase about Diffie-Hellman;

00:00

secure key-agreement without pre-shared secrets.

00:00

What is Diffie-Hellman for?

00:00

Diffie-Hellman helps two communicating parties

00:00

agree upon a key.

00:00

The key that they agree upon will

00:00

be their symmetric key that

00:00

>> they use for data encryption.

00:00

>> What's actually going to happen here is

00:00

Diffie-Hellman is going to come out

00:00

and do asymmetric key-agreement,

00:00

once the key's agreed upon,

00:00

then symmetric data encryption can happen.

00:00

That's a little spoiler for

00:00

later because that's what we want.

00:00

We're going to use asymmetric cryptography to make sure

00:00

both communicating parties have the same symmetric key.

00:00

Because remember, with symmetric cryptography,

00:00

key exchange is the hard part.

00:00

If we use an asymmetric algorithm

00:00

to go out and get the keys distributed,

00:00

then we can communicate with

00:00

that good fast symmetric cryptography

00:00

that we want to use in the first place.

00:00

Diffie-Hellman was the first algorithm

00:00

that did that for us.

00:00

It gives us secure key-agreement

00:00

without having to send anything

00:00

sensitive across the network.

00:00

We also have our friend, ECC,

00:00

which stands for Elliptical Curve Cryptography.

00:00

Its math is based on plotting points along the curve.

00:00

It is a really efficient algorithm

00:00

and it can provide good,

00:00

strong security, but only for

00:00

>> very small amounts of data.

00:00

>> This might be used for encryption of keys.

00:00

Just like we saw, Diffie-Hellman can be used

00:00

for key exchange or key-agreement,

00:00

this can be used for key exchange,

00:00

can be used for digital signatures as well.

00:00

But I want you to primarily focus on using ECC as being

00:00

the algorithm for use with

00:00

handheld devices like our smart phones,

00:00

our smart watches,

00:00

these devices that need encryption,

00:00

but don't have the same degree of

00:00

processing capability that you would have on a desktop,

00:00

or a server, or a larger scale computer.

00:00

That's the big testable piece about ECC,

00:00

is elliptical curve cryptography algorithms

00:00

are used for devices that don't

00:00

have a lot of power capabilities.

00:00

We talked about asymmetric cryptography

00:00

and figured out how all the pieces work together,

00:00

and then we talked about how we get privacy,

00:00

authenticity, integrity, and non-repudiation.

00:00

Last but not least,

00:00

we looked at some of the common asymmetric algorithms,

00:00

and just wrapped up with the function of each of those.

Up Next

Instructed By

Similar Content