I am terrified that I do not consider myself competent enough to write a crypto library, and yet there isn't a single mention - in this article, nor at the time of writing the comments here on Hacker News - of many of the pitfalls I know to avoid when undertaking such an endeavour. There is even a list of "you have to do A, B, C, and that's about it" that is missing some major - well known, even! - items.
I know "don't roll your own crypto" comes across as dismissive or patronising. I'm not a huge fan of the phrasing. But as a first-order approximation, it is correct. If you want to roll your own crypto, that needs to be your _thing_. It's very unlikely you're going to be a fantastic full-stack web developer _and_ be able to do that. If it's really what you want to do then awesome! Go study it, learn it, practice it. But if you're doing it as a side-hobby, never put it into production.
I know "don't roll your own crypto" comes across as dismissive or patronising. I'm not a huge fan of the phrasing. But as a first-order approximation, it is correct. If you want to roll your own crypto, that needs to be your _thing_. It's very unlikely you're going to be a fantastic full-stack web developer _and_ be able to do that. If it's really what you want to do then awesome! Go study it, learn it, practice it. But if you're doing it as a side-hobby, never put it into production.