In particular, SubtleCrypto [0] seems to be what you're looking for. It's in the latest versions of FF/Chrome/Edge/Safari (and according to MDN, shipped with Edge last year and has been supported by Chrome/FF/Safari for roughly 2 years* [1]).
I can't find any support for Opera / IE, unfortunately, although Opera's been based on Chromium since 2013, so... presumably it's been supported for years, as well?
* Cross-referencing against browser release dates, that is.
