Kristina Šekrst completed this course and found the course difficulty to be very hard.
This was a difficult course, and it requires some previous experience with mathematics, otherwise you'll get stuck. The teaching style was fun, the examples were great, and the quizzes were sometimes a bit too difficult, but worth the trouble. The only flaw in this course is that the Cryptography II is, I quote a certain MOOC fellow colleague, "Duke Nukem among the MOOCs", since we're all waiting for the second part, and it's being moved to another starting date every couple of months, so... give us Crypto II! Please!