A specific fun example: I learned the insight that you can make a cryptosystem (stream cipher) out of a PRNG by using your secret key as PRNG seed, and then XOR

A specific fun example: I learned the insight that you can make a cryptosystem (stream cipher) out of a PRNG by using your secret key as PRNG seed, and then XORing your data with the PRNG output stream. The Coursera cryptography course was quite good in general. More in depth: I definitely picked up some concepts in the lectures that I watched. I thought they were better than normal university lectures, mostly because you could skip ahead through them. But in general I think that for me, long assignments are a much more valuable teaching method, and most of the courses I followed/looked at had much too simple multiple choice fact-based questions for the practical part.