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Subject Re: Auth - how much legacy to preserve ?
Date Thu, 11 Jul 2002 14:34:20 GMT

On Wed, 10 Jul 2002, William A. Rowe, Jr. wrote:
> On Wed, 10 Jul 2002, Pier wrote:
>> ...
> Very cool.
> Are you also considering multiple 'user' identities?  E.g., If I'm using client
> cert ssl auth [one identity], with basic encryption [a different identity], it
> would be nice to walk the 'identities' list.
> In that, you could have several types of 'identities' in a list, e.g. 'user',
> 'group', 'role', etc.  The IP and DNS of the client themselves are also
> 'identities', although they are addresses.

I've done some commercial systems in the past which used a token based
evidence scheme. Which worked very well with apache and whcih allowed very
quick integration with apache/per-user-custimization and so on. I.e. along
the lines of:

connection->request->	[ token1 ]
                	[ token2 ]

where the list of tokens would a) increase as the request was more and
more authenticated and b) where the list of tokens collected could
be cached across requests under certain conditions.

	tokenX -> value (*)
		  [ fact1 ]
		  [ fact2 ]

	fact1 -> Username 'foo'
		...more key valye pairs
		 evidence -> evidence3 (*)

	fact2 -> Password '123'
		...more key valye pairs
		 evidence -> evidence3 (*)

	fact3 -> Group 'admins'
		..more key valye pairs
		evidence -> evidence3 (*)
		         -> evidence4

	fact4 -> Group 'plumbers'
		..more key valye pairs
		evidence -> evidence3 (*)
		         -> evidence4

	fact5 -> address, contract number

	fact6 -> SIM card # of WAP-ing phone

	fact7 -> background colour preference

	fact8 -> 1200 airmiles and a gold pass

	evidence3 ->	Source	BasicAuth (*)
			Date	(int) (*)
			Expires (int) (*)
			Use	(flags) (*)

	evidence4 ->	Source	/etc/group (*)
			Date	(int) (*)
			Expires (int) (*)
			Use	(flags) (*)
			key1	value1
			key2	value2
			key3	value3
			key4	value4
			key5	value5

Note:	evidence is not recursive; i.e. evidence itself
	is not based on evidence. Which may have been
	a mistake. But instead something like a GroupAuther
	would insist of evidence from BasicAuth (or other
	constrained vocabulaire Source values) to be
	present before it would run (another problem with
	ordering here!).
Note:	The entries marked '*' are mandatory and have
	a controlled vocabulare/value set. The
	rest are simply ascii-key and UTF8 value pairs.
Note:	The USE flag was not really used - see below.

It worked quite well from the side of the admins and the folks who had to
configure the webserver/radius/tacacs and the systems which integrated
with SS7 telephony layer and the API into the communication with SIM
cards. I.e. they could express what sort of controls they wanted for a
specific directory or something (and some of those where time/resource
consumption depended) and found it easy to extract audit data. Or map out
who was responsible for bad data/deceisions when, say, a complaint came
in that some unwarranted transfer was done.

But... though easy - it was a very 'inefficient' to program modules
against. And occasionaly let to 'storms' of requests to auth backends for
something as silly as fetching a transparent gif spacer.

I.e. when you had to check a 'require' this-and-this property then you had
to go through the whole token->fact (if it is my type)->value sequence for
all the tokens collected.

It was found hard to optimize with, say, a per user property table due to
lot of overlap in KEY values but with different meanings and/or evidence.

Often one set of evidence was required before another set could be based
upon it. E.g. IP address -> Dail-in modem bank slot -> CallerID of calling
line -> entity-which-has-the-phone contract for that physical line.

This lead ultimately to a scheme where one would check for the presence of
a top level token (i.e. has this request got the 'foobar' token) and with
that in handl allow access into the over-18-only gambling site or collect
your airmiles site.

The use flag indicated if evidence could be kept cross request or even
across different servers based on a crypto cookie, SSL info, etc. But over
time the 'use' style flag was used less and less; and rather evidence was
simply destroyed or made inaccessible itself - and the code would detect a
dangling reference and not follow it (at the cost of a cheap in memory
berkely db lookup). I.e. rather than say 'this evidence can only be used
on properly SSL authed connections' one would say - only provide this
evidence to this webserver instance or this set of directories which we
know only allow SSL authed connections in.

There are some paralels with SAML as it is beeing proposed now - and I see
similar problems.

But it sure would be nice to have a ->notes table which is a bit more
fancifull and an apache which has a bit more of a registry behavour when
it comes to registering and coordinating controlled values (or per module
namespaces, etc).


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