Amazing.

perfect

perfect

awesome

so good

希望有中文字幕

thanks

Great！

感觉收获很大

great！

讲得非常好！

nitido

Great!

good

kaif

good

good

none

Nice

god

:)

This is an excellent and challenging course that covers the basics of symmetric key cryptography, authenticated encryption, and public key cryptography. These topics are covered from both mathematical (notions and proofs of security) and computational (algorithmic running times, attacks) perspectives. The material is well-selected and progresses in a logical manner. Many of the key ideas are reinforced through their recurrence throughout the course in different contexts. The individual lectures also have a very natural flow: I would find myself wondering something about the topic under discussion, only to have my precise question answered moments later. Mathematical proofs are often given in a somewhat high-level, intuitive way but without truly sacrificing rigour. The in-lecture questions are well-chosen to force you to really think about the material under discussion and the quizzes, although sometimes challenging, are interesting and help teach material left out or only brushed over in the lectures.

There are also optional programming problems, which were quite instructive. A couple of these involve implementing attacks on insecure cryptographic protocols; a successful implementation would lead to the decryption of an encrypted message, which I found to be not only extremely rewarding, but also especially instructive (much more so than simply implementing a cryptographic protocol, which was the goal of at least one assignment). I found it a bit strange that these highly relevant assignments were optional, however. I suppose this is perhaps so that a programming language is not a prerequisite for the course. However, I think several ideas in lectures would be rather difficult to understand without programming knowledge and in any case the level of mathematical maturity demanded for this course is much more of a requirement than some basic programming ability.

My main complaint really regards the speed at which most lectures are given. It seems to me quite unfortunate that so many hours of excellent lectures were recorded at such a speed that you're basically forced to slow the lectures down (which sounds strange) or pause every few seconds in order to digest the material properly. In a university classroom, you have a fixed amount of time to deliver material, but there's simply no reason to go so fast in an online course.

Overall, a great course! There's always room for improvement. Certain complex and critical concepts were glossed over way too fast in the lectures (with speech compression in the recordings to boot), while other introductory material was gone over too slowly. There is an answer string evaluation problem in the Q's & A's where the required answer must contain a bullet dot to represent multiplication (an 'x' is not accepted) but the standard computer keyboard does not contain a bullet symbol, you have to be in a word processor to create that. Also, there are correct alternative answers for Q#'s 6,9, &12 in the Week 5 Quiz that need to be re-evaluated.

A very good course. The pace is quite high and the material is challenging. I think to get the best out of it you need to spend considerably more time than the course suggests each week and I was not able to do this. However, I have come out of the course with a good understanding of the basic concepts of cryptography and my interest in the subject has been piqued sufficiently to want to find out more!

Course was very fun to learn, and the instructor was very clear and concise with the lecture. I was slightly unprepared for the difficulty level and math involved, but reviewing the videos and discussion group cleared things up. Do not attempt this course without prior knowledge of some discrete math, otherwise it was a very in-depth course which covered many topics, and I would recommend it to peers.