We are also finally ready for applications. This lecture introduces cryptography, and the next few will see the prototype for a cool mathematical encryption system and other similar topics. We will also later discuss practical issues in implementing these – namely, finding HUGE primes and factoring HUGE composite numbers.

By huge I mean something substantially bigger than this:

Those are peanuts by today's standards. But with the tools we've developed up to this point, we are ready for them.