T-Rex: Oh goodness, cryptography. It's really interesting!
T-Rex: Specifically, trapdoor functions are SUPER interesting! Times two!
T-Rex: These are functions that are easy to compute but difficult to reverse-engineer - unless you have the secret 'trapdoor' information. For example, the product of two prime numbers (p and q) is not hard to figure out if you know their values (it's just multiplication!), but if all you have is the answer, n, guessing what p and q are can take a really long time.
T-Rex: And yeah, functions like this are a basis of cryptography!
Utahraptor: How's that?
T-Rex: Well, say I send n to you, and you know what the secret value of p is. There's a chance my message might be intercepted by a bad guy. But this dude will only know n, not p!
Utahraptor: So I'll be able to figure out q easily, knowing what n and p are, but this guy will be totally stumped!
T-Rex: Yep! Of course, all this lets us do is communicate a prime number q in secret to each other. But you can probably do even more things with trapdoor functions!
Off panel: Probably?
T-Rex: I'm almost certain!