Field separators

Brad Fitzpatrick brad at
Sun Jun 5 15:47:16 PDT 2005

On Sun, 5 Jun 2005, Paul Crowley wrote:

> OK.  What format do we use for the replies from servers to consumers
> about server secrets?  We should probably use the same format as that
> for the signatures.  I was thinking x-www-form-urlencoded there, but as
> you say that might be hard for consumers to parse when it's part of the
> reply rather than part of the request.

You'll hear every debate.  Some people will say text/line-based protocol
is easiest.  Some will want x-www-form-urlencoded encoding, and some will
actually prefer XML, as it's built into their language/envifornemnt.

I'd say in the interest of consistency we go with x-www-form-urlencoded.
It's not that hard to parse, and it's usually possible to coerce a web
framework's API to do most the heavy lifting of decoding it anyway.

> I'm keeping a Wiki page up to date with the latest proposed specification:



* What format is p, g, and gx/gy?  Hex, decimal?

* What is dh.q (order)?

* You don't have the check_auth mode for dumb consumers on there?

* We're really using SHA-256 instead of SHA-1?  I thought we agreed
  the point of using a shared secret / HMAC approach over DSA is
  that the uniquity of sha1 functions made implementation easier
  than DSA would.  I just checked 4 or 5 hosts, and it's not available
  on any of them (including any of LJ's).  The Perl package isn't
  in Debian.  SHA-256 isn't in PHP.  etc, etc.

* I don't think the "assert_identity" literal in token_contents needs
  to be there.  It'll just hinder us going forward when it's already
  implied by openid.mode='id_res' and token_content's "assert_identity"
  actual field.

* In the interest of URL space savings, let's cut down the verbosity
  where obvious:
     - encryption -> enc
     - generate -> gen
     - ... eh, can discuss it later.
  Not that we're in trouble now, but for layers later, maybe.  (though
  I imagine the big data will be out-of-band and/or referred to by
  other URLs)

- Brad

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