Cryptopals can be found on https://cryptopals.com/.
Please do not look at the code if you ever plan to do the cryptopals challenges. It is much more fun figuring it out yourself.
I am just using this as a code repo for myself, to be able to work on it from different computers, and to offer people who are entirely lost a look into mine.
I do not guarantee that the code is working, much less optimal / safe. There are no tests, no serious validation, it's just hacked together to make it work in the constraints of the challenge.