Is there a way to tell the acme protocol version from a directory url?

[Neilpang]

For example: a custom directory url: https://myacmeserver.org/directory

How to tell it’s acme version 1 or version 2 ?

Is there a version negotiation ?

[schoen]

I don’t know if there is a more official in-band way, but if you see camelCase directory entries instead of hyphen-ated directory entries, it’s going to be version 2.

A minor wrinkle is that the entries that are randomly added to the directory in either protocol version could randomly happen to match simple regular expressions that aim to detect either form (for instance, the random directory entry might contain a hyphen in version 2 or might start with a lowercase letter followed by an uppercase letter in version 1).

[Neilpang]

@schoen

I don’t know if there is a more official in-band way,

Thanks for your quick response.

Is there any reason that the ACME protocol doesn't have a version negotiation/announcement part ?

I'm just a little worried about the future versions, how about v3, v4, v5 and ......

[jsha]

I would recommend specifically checking for newAccount vs new-acct. The question of explicit versioning came up on the list a couple of times, but we never really reached consensus. The current approach is good enough for now, and we can always add explicit versioning later.