Support digest with SHA-256 and SHA-512/256 as per RFC 7616

[spaskalev]

RFC 7616 defines a new algorithm header field and specifies SHA-256 and SHA-512/256 as valid options. It still supports MD5 for backwards compatibility, but explicitly recommends against it.

[creeble]

Curious about this pull request and/or alternatives.

It seems like this particular PR includes SHA-256 and SHA-512/256, and uses standard libraries. But I can't tell if it's actually complete?

Is there any movement on this? Has anyone tested @spaskalev 's PR?

[spaskalev]

IIRC it worked but it has been nearly five years since I used it :)

[rojer]

fwiw, popular browsers now support it too, including chrome - https://bugs.chromium.org/p/chromium/issues/detail?id=1160478