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Learner Reviews & Feedback for Number Theory and Cryptography by University of California San Diego

446 ratings
91 reviews

About the Course

We all learn numbers from the childhood. Some of us like to count, others hate it, but any person uses numbers everyday to buy things, pay for services, estimated time and necessary resources. People have been wondering about numbers’ properties for thousands of years. And for thousands of years it was more or less just a game that was only interesting for pure mathematicians. Famous 20th century mathematician G.H. Hardy once said “The Theory of Numbers has always been regarded as one of the most obviously useless branches of Pure Mathematics”. Just 30 years after his death, an algorithm for encryption of secret messages was developed using achievements of number theory. It was called RSA after the names of its authors, and its implementation is probably the most frequently used computer program in the word nowadays. Without it, nobody would be able to make secure payments over the internet, or even log in securely to e-mail and other personal services. In this short course, we will make the whole journey from the foundation to RSA in 4 weeks. By the end, you will be able to apply the basics of the number theory to encrypt and decrypt messages, and to break the code if one applies RSA carelessly. You will even pass a cryptographic quest! As prerequisites we assume only basic math (e.g., we expect you to know what is a square or how to add fractions), basic programming in python (functions, loops, recursion), common sense and curiosity. Our intended audience are all people that work or plan to work in IT, starting from motivated high school students. Do you have technical problems? Write to us:

Top reviews

Jul 31, 2020

I loved this course! It is unlike any I have taken before. All courses in this specialization have always included fun activities to make the taught content fun and understandable.

Nov 21, 2018

I was really impressed especially with the RSA portion of the course. It was really well explained, and the programming exercise was cleverly designed and implemented. Well done.

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51 - 75 of 91 Reviews for Number Theory and Cryptography


Nov 29, 2020

One of the best courses I have taken so far!!

By Zhen X

Jun 24, 2020

The last week of this course is very amazing!

By Gaoge Z

Jul 31, 2020

Great RSA Quest. Fun and engaging!

By Hans D E H

Sep 18, 2020

I loved the quest, was very fun!

By Snehalkumar D P

Jul 13, 2020

Excellent Course and Very Useful

By Chandrakala P

May 3, 2020

Faculty gave good explaination

By Angel G

Jul 27, 2020

Excellent (Excelente)

By Afnan A

Aug 15, 2020

It was awesome!!

By V. Y

Jul 10, 2020


By Dhruv P

May 3, 2020

The best!

By Preetam K S

Aug 3, 2020

Good one

By Satyam K M

Jun 1, 2020


By Luis M V F

Jan 11, 2020

In general, this course is much better than the previous 3, and I enjoyed all weeks but Week 4. I think Michael Levin should improve his explanations, and also try to give further examples about the algorithms he is talking about. I would say that it is worthy taking this course, but I really hope Week 4 can be improved.

By Greg L

Dec 11, 2017

Generally pretty good. Pretty easy level, and the maths is undemanding. Some imprecision in the wording of the tests, and a little too easy on the programming side, but well worthwhile if you still have some holes in your understanding of the principles of RSA encryption.

By Stephen L

May 11, 2018

The class was interesting but I felt it was difficult and not explained do the modules I had to constantly go back and re-read the slides, re-watch the lectures. There weren't any examples, I feel it would have been helpful in order to grasp the material.

By Md. A K

May 7, 2020

The instructor tried their best to explain difficult topics like cryptography to make as easy as possible. For this, they really deserve great appreciation. It can be improved if they did not just read out the slides but explain them in some places.

By Aren T

Nov 19, 2019

Final week is a bit rushed, think it would have benefited from being one week longer.

Nevertheless, an excellent introduction to an extremely difficult and complex subject.

By Stephen S

Apr 18, 2020

Great introduction to number theory, with little to no assumed knowledge. Proceeds quite quickly, but remains relatively simple and introduces concepts well.

By Gautham A N

Dec 9, 2018

Amazing course, learnt a lot. The assignments were a bit difficult [ and time consuming ] but they helped me gain a better understanding of the concepts.

By Ivan L F

Apr 8, 2018

Good material and presentation from the professors. Programming exercises were a bit confusing at times. Overall, short but mathematically solid course.


Jul 6, 2020

It was a great course which helped me learn number theory and introduced me to Cryptography.

The teaching assistants could have been more active.

By Mariam M

Nov 8, 2020

It was good, one needs an advanced level of python coding to get through howecer the final assignment I enjoyed quite a lot.

By Alex Y

Jan 17, 2019

Sometimes material is very dense. Watching in 1x speed multiple times advisable for some modules later in the course.


Aug 4, 2020

The last week of the course makes everything else in the course so worth it! Had a great time doing this course!

By Rick B

Aug 14, 2020

Slide and instruction could use more concrete examples, but final project was excellent.