captcha

Breakthroughs in generative AI have created enormous opportunities for humans to learn from computers. We can use them to explain the news, understand historical concepts, fix our coding errors, and so forth. But of course, AI also has to learn from human. The technology digests enormous amounts of written text, and often relies on human feedback to calibrate its models. Luis von Ahn has been at the forefront of these back and forth interactions for years. He is currently the CEO and co-founder of Duolingo, the language learning app, but prior to that, he was one of the original developers of CAPTCHAs, the little puzzles you solve to log into websites and prove that you're a human. And of course, in the process of proving your humanity, you're also training computers to get better at identifying red lights, cross walks, bicycles and wavy letters. On this episode, we discuss the history of his work, the future of CAPTCHAs, the success of Duolingo and how he is using today's advanced AI models in aid of language learnings.

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In 2000, Luis von Ahn was starting his PhD in computer science when he attended a talk and happened to learn about one of Yahoo's biggest problems: automated bots were signing up for millions of free Yahoo email accounts, and generating tons of spam. Luis' idea to solve this problem became CAPTCHA, the squiggly letters we type into a website to prove we're human. He gave away that idea for free, but years later, that same idea had evolved into a new way to monetize language learning on the web, and became Duolingo. Today, Duolingo is a publicly-traded company with a market cap of $9 billion.

This episode was produced by Casey Herman, with music composed by Ramtin Arablouei. It was edited by Neva Grant.

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In this Hasty Treat, Scott and Wes talk about ways to prevent malicious people from using or abusing your app.

Linode - Sponsor

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Show Notes

• 00:26 Welcome
• 01:04 Sponsor: Linode
• 02:06 Sponsor: Sentry
• 02:59 What kind of bad things can happen to your application?
• 06:24 How do you stop bad actors?
• 12:20 Nonce tokens
• 14:10 CSRF
• CSRF Explained
• 14:50 Captcha
• hCaptcha
• 17:06 DDOS
• Cloudlfare DDOS
• 17:38 Ban known bad ASNS

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• Scott’s Instagram
• LevelUpTutorials Instagram
• Wes’ Instagram
• Wes’ Twitter
• Wes’ Facebook
• Scott’s Twitter
• Make sure to include @SyntaxFM in your tweets

In this Hasty Treat, Scott and Wes talk about forms, captchas, dealing with malicious users, and more!

LogRocket - Sponsor

LogRocket lets you replay what users do on your site, helping you reproduce bugs and fix issues faster. It’s an exception tracker, a session re-player and a performance monitor. Get 14 days free at logrocket.com/syntax.

Show Notes

02:00 - So you made a form:

1. Contact form
2. Sales form
3. Email signup for newsletter
4. Bug report
5. Sign up for an account
6. Password reset

03:00 - Now someone is going to:

1. Have a bot that submits it
2. Maliciously write a bot that submits thousands

04:14 - So what can you do?

4:54 - Honey pot

• This is a field that is either hidden or you tell the user not to fill in
• Can goof up autofill
• Works in many cases

07:37 - IP Throttle

• Only allow each IP to do an action a certain number or times inside a window
• You may only try signing up once per 10 mins

09:48 Block known ASN

12:37 - Captcha

• Soft captcha: “What is 1 plus 1?”
• Annoying captcha: Type these letters
• Google captcha: Train our self driving cars
• Hidden captcha
• Cloudflare hCaptcha

Links

• Cloudflare
• Digital Ocean
• Google reCaptcha
• Cloudflare hCaptcha
• Cloudinary

Tweet us your tasty treats!

• Scott’s Instagram
• LevelUpTutorials Instagram
• Wes’ Instagram
• Wes’ Twitter
• Wes’ Facebook
• Scott’s Twitter
• Make sure to include @SyntaxFM in your tweets

Also: is there such a thing as too much science? With special guest Luis von Ahn.