"The Cryptopals Crypto Challenges" (a.k.a. Matasano Crypto Challenge) https://cryptopals.com/ https://cryptopals.com/ "This is a different way to learn about

"The Cryptopals Crypto Challenges" (a.k.a. Matasano Crypto Challenge) https://cryptopals.com/ https://cryptopals.com/ "This is a different way to learn about crypto than taking a class or reading a book. We give you problems to solve. They're derived from weaknesses in real-world systems and modern cryptographic constructions. We give you enough info to learn about the underlying crypto concepts yourself. When you're finished, you'll not only have learned a good deal about how cryptosystems are built, but you'll also understand how they're attacked."