On which API are you using this?
The answer is Yes. Just have created an Etsy plugin recently that use this.
I also have to use this in another plugin in the past. Not sure if this is the same library, but needed to SHA-1 HMAC (or 256) signature.
A link to API doc?
There’s some plugin that might help that can create some encoding. But actually without API Doc it’s hard to tell you if this can help. ZQ have an oAuth1 plugin that can help. There’s also some plugin for SHA1 HMAC.
I’ve created plugin because this is very complex to use this kind of authentication and most plugin actually cannot handle this.
So, I think I understand their doc and how they use the jsSHA (and yes this is the library I use actually).
I think that the ZQ plugin should work with API Connector for you case. (The Encrypt HMAC one, not oAuth1)