Hey everybody, welcome back to explain back on five the podcast where we take the questions you always want to ask and talk about In a way that's easy to understand we are your hosts. I'm Tim and I'm Kevin So Kevin today we're talking about where's Waldo? So first of all, I know this book series as wears Wally since I grew up in a British English system But I think you know it as where's Waldo. Oh, yeah He is only called Waldo I believe in the US and Canada and that's because the book was originally published as a British series of children's puzzle books created by the English illustrator Martin Hanford back in 1987 It's been a huge success It sold over 70 million books But actually not always as where's Wally since he has regional specific names like Waldo This series of pictorial puzzle books has been translated over, you know 26 languages and it's published in over 50 countries.
It is so distinctive So how did Hanford come up with the idea for where's Waldo? Ah, yeah So Martin Hanford was a graduate of the University of the Creative Arts and Kent at the time And he was asked by his art director to develop a book of detailed crowd scenes for the children's book publisher Walker Books And while the book was being prepared for an abalone of book fare Apparently someone at Walker Books suggested the idea of adding a pretty distinctive looking character whom the reader could search for in all the big crowd scenes And this led to Hanford coming up with an idea of Wally, you know This world traveler and even time travel of fiction Otto who always dresses and very distinctive red and white stripes Apparently it will sometimes take Hanford up to eight weeks to draw a two-page sketch of the elusive Wally and the characters surrounding him And one interesting fact to what is that the subsequent books in the series as they've been released Wally or Waldo gets harder and harder to find Oh, yeah, indeed They have as the book series has gone on Wally progressively has become harder to find and this is quite quite a fact And how do you measure this hard to find fact? What they've been doing is they've been reducing his size on the page and also surrounding him with a lot more characters Hmm. So in the first book Wally was on average maybe about one square centimeter and over time He reduced to point eight square centimeters and then point three square centimeters And now between point two or even point one seven square centimeters in the subsequent books He's also been surrounded by just more characters, you know from the very first book if there was about 225 characters on the page now to about 850 Oh, wow And there are a number of other characters and people in these illustrations too if the illustrations always spread across the two pages of the book That's right.
There are all these you know beautifully drawn double-page spread illustrations painting dozens or more characters doing a variety of Amusing tasks and things and a given location and readers are challenged to go find a character named Wally or Waldo hidden somewhere in that group He's identified by this very distinctive red and white striped shirt a bubble hat and glasses But the clever thing is that they also do is that in many illustrations that contain red herrings Evolving deceptive use of you know red and white striped objects that might look like it's Wally was not I see now We talk about Wally and Waldo in British English and in America, but what are some other names that we have for Wally around the world? Yeah, here's a whole list so you got Waldo in the United States, Canada He's known as Charlie in France Walter in Germany Ali and Turkey F.E. in Israel You baldow in Italy Hugo in Sweden and Willie in Norway. Oh, wow, that's quite a variety now The creators did not intend for this but it turns out that where's Waldo or where's Wally is actually now a well-known example in cryptography Oh, yes, it has a funny a very important use as an example in cryptography in something called zero knowledge proofs in Eli five terms The idea with zero knowledge proof is to try and demonstrate that you know a thing without actually revealing that thing Mmm technically defined it's basically a method by which one party can prove to another party that a given statement is true While avoiding conveying to verify any information beyond the mere fact of the statement's truth interesting So how does where's Wally come into all of this so one well-known example of a zero knowledge proof is using where's Waldo?
Let's say that the prover wants to prove to the verify that they know where Waldo is in one of the illustrations without revealing the actual Location to the verifier. Oh, that's an interesting use case. Okay, that brings zero knowledge proof to life So how do they do it? It's pretty clever the prover basically starts by taking a large blackboard with a small hole in it Besides Waldo and the board is also twice the size of the book in both directions So the verifier cannot really kind of see where on the page the prover is placing it the prover then places the board or the page So that basically Waldo is visible in the hole now the verifier right can look through a hole and see wow you did find Waldo But they cannot see any other part of the page.
Oh, I see so the prover has demonstrated to the verifier that they do in fact Know where Waldo is without revealing any other information about Waldo's location Exactly and so that's why where's Waldo is actually commonly used in cryptography lectures around the world for this very topic very interesting But unfortunately, it's not completely perfect a zero knowledge proof, right? Yeah. Yeah, if you want to be a picky about it It's not exactly perfect because the prover does reveal some information about Waldo's location Such as maybe his body language. However, you know, it's a decent illustration of the basic concept of a zero knowledge proof It definitely is did you let something new if you did send us an email?
We are at ELI 5 the podcast at gmail.com We love hearing from you Especially when you have comments and suggestions for us if you are a regular listener for podcast Please take the time to leave us a review or rating on Apple podcasts because it does help other listeners to discover our show As always thanks to the community at our slash explain them five and we will see you all next week