Please add a non-standard `crypto.KeyedDigestStream` (or future-standard `crypto.subtle.sign` iterator input) for computing streaming HMACs

[johnspurlock]

Web crypto doesn't support streaming hashes, and the current non-standard crypto.DigestStream is hash only (no keys), so it is impossible to compute a streaming HMAC without pulling in a JS implementation (which is more costly and less efficient).

Would love to have a similar crypto.KeyedDigestStream or even crypto.HmacStream since this is a very common signature in practice.

Thanks!
- John

Update: crypto.subtle.sign('HMAC', cryptoKey, bytesIter) would be even better (see below)

[kentonv]

It looks like there is a node crypto API for this -- any reason not to use that instead?

In retrospect I think the right way to handle streams in WebCrypto really would have been to make all the operations support specifying a ReadableStream for data...

[jasnell]

the current direction the standard is heading is to support async/sync iterators as input to some of the operations.

[johnspurlock]

that's good news - in that case, no new non-standard api surface

then perhaps a cf early implementation for crypto.subtle.sign('HMAC', cryptoKey, bytesIter) and just a note in the docs is all that is required?

[jasnell]

Yep, already on the radar :-) ... it's been a lower priority for me so far as we've been focusing on some other areas but I'm wanting to get back to this later this year (likely closer to the end of 2Q)

[johnspurlock]

nice, so glad to hear that - will keep a keen eye on the workers changelog