Martin Kleppmann and I created a children's book about cryptography (youtube.com)

I owe a huge thank you to Hacker News for encouraging me to make more books like last year's Gently Down the Stream (https://www.gentlydownthe.stream/). If I can answer any questions, please let me know. Martin and I will be hosting an AMA on Reddit (https://www.reddit.com/r/IAmA/) today, as well :)