[vengefulduck]

The math used in AES (Rijndael) utilize operations in GF(2^8) tho, so you're doing operations using Galois fields whether your utilizing GCM or CBC. I don't really see how adding the GCM mode utilizing GF(2^128) on top is significantly more difficult or error prone than implementing the AES block cipher itself. You should still be familiar with operations over Galois fields regardless if you've for some reason (foolishly imo) decided you want to implement AES cryptographic primitives on your own.

Regardless there's no good reason not to use a vetted open source implementation instead, preferably with an even higher level of abstraction so your not having to worry about ciphers or modes of operation at all[1].

[1] https://doc.libsodium.org/secret-key_cryptography/secretbox

[dragontamer]

The library used in this Javascript widget has AES already implemented, but not GCM mode.

> Regardless there's no good reason not to use a vetted open source implementation instead, preferably with an even higher level of abstraction so your not having to worry about ciphers or modes of operation at all[1].

I think that's generally the preferred solution, yes.