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Is everybody having a good day?

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That's awesome, I'm so glad to hear that.

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I had no idea how cool Roots Asylum was,

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but you people have drone wars in here.

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That's amazing.

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Encrypted relay race, that's wonderful.

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I'm here to talk to especially the kids today

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about how to tell your friends about crypto.

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I would love it if each and every one of you

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had the chance to teach one other person about encryption,

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about how you communicate with somebody else

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and feel safe doing it.

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Who wants to learn about that today?

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That is amazing, I'm so glad to see it.

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Can we get especially the little kids

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up a little closer to the front?

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You're gonna get a chance in the next 10 minutes

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to solve your own small crypto puzzle

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and learn how to teach your friends about cryptography, okay?

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Come on up, there you go.

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Just sit down right here, we're good.

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All right, come on on up.

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I have a faithful assistant today,

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my own friend,

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my awesome brand new husband, Deviant,

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and he's gonna do us a favor

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and pass out crypto puzzles to the kids up in the front.

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Does that mean, there you are.

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So hi, I'm Tara.

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I do stuff here at DEF CON

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and I'm gonna show you how to use a game

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I learned when I was in elementary school

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to teach other people about cryptography.

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I was kind of a nerd and I like to play games too,

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so this is my natural home, folks.

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All right.

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All right.

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I like games of every kind, every stripe.

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I love poker, which makes Vegas pretty fun and happy for me.

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And I learned about six or seven years ago

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more about cryptography than I thought I'd ever have to.

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I don't do crypto normally.

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Actually, most of the time,

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I run a security operations center

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or I do incident response.

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And in security, that's about doing stuff fast.

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Sometimes crypto is about doing stuff fun and slow.

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So let's learn a little bit more about it.

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Who knows what cryptography is?

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Best guess with one word.

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Best guess?

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What is it?

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Wonderful.

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It is the study of coded messages.

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That is fabulous.

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What does crypto mean?

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It means a secret, right?

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It means something that you don't know.

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Cryptography is just a secret

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that you and someone else have put together

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so you can hide a message and then unhide it, right?

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Good.

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Does anybody up here know what this crypto is right here?

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You ever seen it before?

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Come on, I know you know.

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Caesar's cipher.

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It's one of the, oh, I heard a kid's voice back there

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shouting Caesar's cipher.

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Come on up here and sit down.

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You're gonna get a crypto puzzle in a minute.

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All right, this is a Caesar's cipher.

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The easiest way to explain to your friends

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what cryptography is is a substitution cipher, right?

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When one letter of the alphabet means a different,

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different letter of the alphabet.

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It's really easy to understand,

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and it's something I'm gonna show you how to do today, okay?

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Does anybody in here know what rot or rotate 13 means?

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If a Caesar's cipher, oh, go, bring it.

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Yep.

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And you add 13 to it, that's wonderful.

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So in rot or rotate 13, what is the letter A equal?

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Does anybody know?

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M. M, awesome.

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I heard a little girl back there.

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Come on and sit up at the front if you'd like to.

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That's right, an A equals an M in rot 13,

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and you're all gonna get a chance

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to do this kind of puzzle in just a minute.

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This is what it looks like.

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It's why we call it rot or rotate.

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It's just a wheel of letters just like this.

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And if you want to, you can look those up

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on your phones right now or any machine you have

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in front of you and pull up a rot 13 alphabet, okay?

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If you wanna play along, and I highly advise it,

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Does anybody know why people at crypto parties

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who are kinda nerds like to joke about rot 26?

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What is A in rot 26?

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The little girl back here.

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It's A, bravo, awesome, I'm so glad you said that.

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That's why it's funny, right?

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If you encrypt something with rot 26,

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it's just the alphabet again, and it's really funny.

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Very good.

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You can come to my next party.

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Does anybody know what this is?

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It's a box.

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It's a box you can open, and it's called a,

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anybody know?

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Adults are allowed to guess on, cryptex, awesome, yes.

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Didn't even require an adult on that one.

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A cryptex, it's a box you can open

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by understanding a substitution cipher, just like this one.

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That's just what your locks are on your lockers

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at school, by the way.

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Not that I'm giving you any hints.

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That's my husband's job.

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He'll teach you about locks and breaking into things

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in a little bit.

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Does anybody know what this is?

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The secret to cryptography is never being scared of it.

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This is called a Vigenere cipher, and this is just where

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cryptography went over the last several hundred years.

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But the basis of all of these secrets is just knowing

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that one letter is gonna stand for another letter, okay?

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Sometimes you need a secret in crypto to be really,

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really strong.

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So if all you have for information is just one letter

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and another letter, sometimes you add in something,

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that gives your cryptography a little bit of randomness.

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What is that little bit of chaos called?

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Does anybody know?

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You use it with pepper.

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Salt, exactly.

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You add a little bit of randomness,

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and then you get something that only you

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and somebody else can unlock.

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Who's played this game before?

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Mansion, apartment, shack, house.

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This is so great.

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I did this talk yesterday for crypto and privacy,

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Village, and almost none of the boys got it there.

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All the girls played Mansion, apartment, shack, house

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when they were in elementary school.

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And if you were like me, you counted in advance

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backward in your head to make sure you ended up

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with Bobby from the third grade.

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So this is a game that lets you show people

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how cryptography works.

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It rotates in a circle, and you pick out and eliminate

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the different choices that you have after you set yourself

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up with Porsches and mansions and fun stuff like that.

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You do it by drawing a spiral circle until someone else

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who's not looking says stop, and you count the rings.

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The number of rings outward is how many times

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you go around the circle, right?

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So you have your randomness, you're going around

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in a circle, and you're eliminating choices

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until you end up with a final sentence.

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I live in a mansion with Bobby, and I drive a Porsche.

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And I still have student loans, which most

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of the adults would get, all right?

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So here's the question.

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This right here is the opposite of a Caesar cipher, okay?

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It's A, X plus three.

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A equals the letter that you're going for, plus three.

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If A plus three is our crypto, what does X equal?

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What is the letter you're gonna get?

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Best guess?

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It's the opposite.

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So if a D is an A in a Caesar cipher,

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what is an A in the opposite?

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It's a D, good, exactly.

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Now we understand.

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What cryptography is is just adding stuff to this equation

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until it gets so complex that people can't guess it

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really easily.

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Then you add the randomness in so that computers

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can't guess it really easily, right?

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Exactly.

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Now we have a secret one person has and another person has.

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In just a second, you're gonna do your own

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ROT 13 translation, but I want you all to realize

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the only thing cryptography is when you explain it

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to your friends, and please, explain it to your parents too,

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because it's an equation that lets you translate

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numbers and letters, okay?

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Sound pretty fair?

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Not scary at all.

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In fact, it's a lot of fun for puzzles and games.

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So as you're sitting at your computers,

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I want you to recognize that all you're doing

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is just letting your computer translate a secret for you.

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So for all the kids up here who wanna try their own puzzle,

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I'm gonna ask Debian over here to pass out

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the small slips of paper.

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You already got, does everybody have a slip of paper

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that wants one?

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Everybody's got one that wants one?

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Okay.

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I would like you, if you don't have a ROT 13 alphabet

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pulled up on your phone or your computer

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to share with a friend and translate the secret

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that I gave you, all right?

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I don't know you, but I know what code you need to use

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and so do you.

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So give it a shot.

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The first person that calls out what their secret is

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and do it by yourself without your parents

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or with your friends, the first person that calls that out

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gets the raspberry pie I just won for knowing comic book

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stuff.

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What is it?

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Road trip.

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We have a winner of an apple pie.

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Let's bring it.

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Apple pie.

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Wait, no, that's a raspberry pie.

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I'm hungry.

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I need apple pie really badly.

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Congratulations.

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Keep translating.

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Now, there's more prizes, all right?

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Come and talk to me later on if you want to try to translate

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a random rotation.

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What is something that a random rotation might be?

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Right?

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If it was the, you know, a rocket that was flying.

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Rot 5. What do you think A would be in Rot 5? E, exactly. That's the answer. So I would love it if

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you come up and get more advanced puzzles and try it out. For those of you that haven't tried

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crypto puzzles before, try a site called rumkin.com and try translating it in all the different

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rotations you can find. This is all cryptography is. It's how you keep those messages safe and

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secure. Yes, I'm sure. And the thing I want you to remember is that when you get the chance,

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explain to everybody that you know, crypto's not magic. It's just a little bit of math and a whole

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lot of trust and the ability to talk to people and feel safe doing it. Y'all get the idea? Yes?

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Awesome. I am so proud. Ask me anything you want to know. I don't do this for a living. I just

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kind of get it. And if you want to know these puzzles, it's a great idea if you want to grow

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up to be a hacker.

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A little bit about crypto too. Thanks, kids.