Lately, I’ve been working through the challenges at Cryptopals.com. The problems are organized for learn-as-you-solve method supplying the groundwork for later challenges. Cryptography is relevant given increasing number of actors involved in data theft from business competition to overreaching government agents. Even if cryptography isn’t your field, the problems are good practice for beginners or advanced programmers keeping skills in shape. Solve problems in your preferred language, or to help learn a new language. I’ve been working through the challenges in C# to round out some areas I haven’t had as much practice with, and also in Swift since it’s still new to me. It’s a good bit of fun.
Go ahead, give Cryptopals a try.