The SHA-256 Project: learn how hash functions work by implementing one yourself
I really like this. Cryptography is obviously very hard to get right and complex, and for that reason people have said "don't roll your own crypto" - but really, that's stupid. What we need is accessible information to explain cryptography to people, so they know how to make smart crypto decisions, know what pitfalls exist, etc.I think crypto has done a particularly bad job of providing accessible materials, historically, and has had a terrible attitude towards doing so. Things are changing, and that's nice.