x/crypto/acme: implement ACME RFC 8555

[x1ddos]

RFC 8555: https://tools.ietf.org/html/rfc8555

---

Let's Encrypt is planning to roll out the next version of ACME which they call API v2 endpoint:
https://letsencrypt.org/2017/06/14/acme-v2-api.html

It isn't clear yet what v2 will actually look like because the latest ACME draft v07 has not been standardized yet:

We refer to "V2" as whatever will be standardized by the IETF as an RFC.
The ACME specification hasn't become an RFC yet - draft-07 is the current document
being worked on. It's likely very close to what will be the RFC and the "V2" that we implement.

(from https://community.letsencrypt.org/t/request-whats-new-in-acme-v2-post/37042/6)

Here's the diff between the currently implemented protocol and the latest draft version:
https://tools.ietf.org/rfcdiff?url1=https://tools.ietf.org/id/draft-ietf-acme-acme-01.txt&url2=https://tools.ietf.org/id/draft-ietf-acme-acme-07.txt

The issue is to track that work. Just want to get a head start.
@bradfitz please, assign this to me.

[x1ddos]

A set of testing-focused packages implementing the upcoming Let's Encrypt endpoint: https://github.com/letsencrypt/pebble.
Could be useful.

[mdlayher]

Sorry for the noise, trying to edit the issue on mobile.

[mavimo]

@x1ddos @mdlayher a new draft is available https://datatracker.ietf.org/doc/draft-ietf-acme-acme/
I'm start looking on it and seems there are infos needed to start work on it, do you already implement some part of specs? I'm considering to start work on it...

[x1ddos]

@mavimo I haven't read it yet. Do you know if that's the closest to what v2 will be based on or will there be more iterations?

[mavimo]

@x1ddos tech spec seems stable (endpoint naming, response payload, ...) but spec are not closed. I suppose should possible starting a WIP implementation (using pebble) to test client implementation.

https://github.com/ietf-wg-acme/acme/
https://tools.ietf.org/wg/acme/agenda
https://datatracker.ietf.org/meeting/100/materials/slides-100-acme-acme-acme/

[kf6nux]

From Let's Encrypt,
"We are planning to have a public test API endpoint up by January 4, and we’ve set a date for the full launch: Tuesday, February 27."
https://letsencrypt.org/2017/12/07/looking-forward-to-2018.html

[x1ddos]

Would've been nice if they actually referred to some documentation, unless it's going to be exactly the latest IETF draft but I have some doubts.

[cpu]

@x1ddos any observed divergences from draft-09 would be welcome as issues on the Boulder repo.

[x1ddos]

@cpu yeah I saw the announcement not long ago. This is great! Will make sure to file issues if I notice anything.