I maintain a set of cryptography algorithm implementations. They are written from scratch following the relevant official standards. Some of them originated many years ago in my late teens when I was writing them primarily to learn the standards myself.
These implementations are hobbyist implementations. They are not optimized for speed or code size, and they do not have preventative measures for side channel attacks. They are published for educational value and to provide reference, restriction-free code that implements these popular standards.
The project, with more details about the licensing and such, is hosted here: Cryptography Implementations on GitHub.