Implement Symmetric and Asymmetric APIs

[alanssitis]

Hi @lpil!

I want to contribute and add encryption support to the standard library. I am still new to gleam and would appreciate some guidance as it seems to be a pretty big undertaking. I will use this issue to track my progress and write down how I build this API.

Before I start, here are a few questions I had:

• One main issue, is there a proper way to handle algorithms that are supported by one platform (erlang crypto) and not by the other (WebCrypto)?
• Should we separate asymmetric and symmetric encrypt?

[lpil]

Hello!

If we're unable to support both platforms then we'll have to defer that addition until we can.

I don't have any particular opinions on the scope on this library beyond wanting to cover the most generally useful crypto bits and bobs one might want in a typical application.

Thank you.

[alanssitis]

Sorry, I wasn't clear in my question, but if one platform supports only RSA encryption while the other supports many more, should I just implement RSA?

[lpil]

All functionality must support both targets, aye

[chiroptical]

@lpil I'm able to generate chacha20-poly1305 ciphers in both runtimes. Would you like me to try to add those?