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Subject: Comments on SAML 2.0 Core draft-19...
- From: "Conor P. Cahill" <firstname.lastname@example.org>
- To: SAML <email@example.com>
- Date: Sun, 8 Aug 2004 22:40:35 -0400
So, I've been spending some time reading through the latest core spec
(yes, Jeff, it's about time) and have the following
feedback/commnets/question (line numbers from the *NON* diff pdf file):
It would be really helpful to one reading the spec to have some
examples showing implementation of the various schemas (i.e. a sample
NameIdentifier element). This is especially helpful to one who is not
an XML Schema expert.
Timestamps are treated with different prose in different places
throughout the document (Lines 634, 636, 688, 691, 755-758, etc.).
Suggest that we have one definition of timestamp values (as we do in
section 1.2.2) and the remaining places all refer to that section. So
line 634 (and 688) would be along the lines of "A time instant (see
Section 1.2.2)...." and the prose on lines 755-758 would be deleted.
Why do we have separate attributes for MajorVersion and MinorVersion?
Can't we have a single attribute called version with a fixed decimal
format (2.0). Also, can't we make MinorVersion optional so that if it
isn't present it defaults to zero. This applies to the assertion
itself, as well as the RequestAbstractType.
407 & 470 - if no Format valie us provided the *identifier* is in
effect. I suggest changing the word identifier to be "value" since we
are talking about a value here and this is in the "Name Identifiers"
section which makes the word identifier a bit confusing.
560-565: The way this is laid out in the schema, I can have 0 or more
of the 4 statements in a random order. I would rather see this done by
removing the choice and then having the 4 statements listed with min=0,
max=unbounded. That way the statements of the same type all come
573-603: I'm a bit confused here. Lines 575 says that the Subject
"contains a name identifier, a series of one or more subject
confirmations or both". The schema says that you either have a name
identifier with zero or more confirmations or you have one or more
confirmations (in other words, you could have just a name identifier,
or you could have just a confirmation or you can have both).
573-603: What's really confusing to me is what the heck is a Subject
without an identifier but which has a confirmation? That should be
explained in here somewhere.
722-731: These make statements as to the validity of the assertion
based upon the conditions. I think that it should refer to the
condition check step in the validation process rather than saying that
the assertion is valid. So, if the condition is not met, the
condition check step fails. If the conditions are not specified, empty
or all are met, the condition check step is passed. I don't like the
current statement on line 724-5 that says 'the assertion is considered
to be Valid". Similarly, I would say that conditions are met
or not met (as opposed to valid or invalid -- the conditions themselves
are (almost) always valid, it's just whether or not they are met that
is of interest here).
188.8.131.52.4 (One Time Use): I think we should have some prose in here
about the fact that the consuming entity should only accept such an
assertion once (e.g. if the same assertion is presented again, even
within the validity window, it should be refused). It would probably
also be interesting to have some form of a recommended timeframe to
keep track of these (perhaps twice the validity period or something
949-950: "That is, it MUST NOT be used in subsequent assertions about
the same principal" probably should be clarified to be "That is, it
MUST NOT be used in subsequent assertions given to different relying
parties about the same principal".
1083: "then the" at the end of the line should be just "the"
1430: Status should not be required. If not present, it should be
that I think this awful lot of stuff to just say "OK".)
1483: Do we really mean "permissible" or do we mean something along
the lines of pre-defined. I don't think we should limit the status
codes to the ones we can think of right now.
1484-1536: Do we really need these to be urn's? Can't we just reserve
unqualified strings as our own and let people who want to extend this
list to define qualified strings? It's not like we expect our internal
status codes to collide.
1832: Suggest changing "it" to "the Identity Provider" to make it clear
what "it" is.
1831-1836: This reads like the subject must authenticate and then
submit the AuthnRequest. That isn't the case. The security
context/Authentication can be established *after* the AuthnRequest is
received by the IdP.
1873: Strongly recommend that IsPassive default to "false" not True.
The passive request is the exception to the rule and the default should
be set accordingly.
1918-1919: The ForceAuthn and IsPassive attributes don't have defaults
specified in the schema. Is this on purpose? I would think if we set
a default we should define it in the schema.
1937-1941: I can't tell what's supposed to go in this attribute. I
presume it specifies the namespace of the name identifier in the
resulting assertion, but that isn't clear here.
1942-1946: I thing this is a bit watered down from what it should be.
Essentially this is specifying that the Requesting Entity is asking
the Identity Provider to establish a new relationship identifier
(federation identifier) for the subject at the relying party. I also
think the default should be "False". Suggested wording:
boolean value used to indicate that the requesting party would like the
Identity provider to create a new federated name identifier (if one
doesn't already exist) for the subject at the relying party. Defaults
to "false". When "false" the AuthnRequest should fail unles an
existing federated name identifier exists for the user at the relying
1955-1956: I found the current wording confusing. Suggested
of the Format in the <AuthnRequest>, the IdP may return an
<EncryptedID> in the resulting assertion if the policies in
effect at the IdP or the SP require <EncryptedID>s.
- Line 2010:
Where is GetComplete defined? I presume section 184.108.40.206.2.
- Line 2014: I
presume this should be 220.127.116.11.1 as it is a sub-element of IdPList.
2047-2048: Suggest adding "or if prevented from providing an assertion
by policies in effect at the IdP (such as the Subject has prohibited
providing assertions to the relying parti)" as a condition resulting in
2064-2066: This makes me think that the relying party and the request
issuer must be the same entity. I would think that only the Relying
party MUST be included.
2138-2139: There are other very reasonable reasons for using
artificacts other than size. For example it allows one to use
non-signed assertions if they are presented on a secure channel between
the IdP and the Relying party.
2177-2178: This makes it look like the response must be signed (at
least it could be read that way by an uncareful reader). Suggest that
we add something that says it's OK if the message is not signed when it
is presented over a secure channel (yes, the current prose covers this
with the "otherwise" clause, it's just not clear to someone who hasn't
been working on this stuff for a while).
2194-2196: If the status must be present and it MUST have a specific
value, why require it at all. It doesn't add any semantic value
here. I would rather see it just absent.
- Line 2195:
There's no code value "Success" (although I think there should be).
2242-2263: Suggest making "terminate" an optional boolean attribute and
not an element. If we're gonna keep it as an element, we need to
define the type (right now on line 2263 it's an empty complex type).
- Line 2272:
There's no guidance as to whether or not it's ok to mix a NameID with
an NewEncryptedID or an EncryptedID with a NewID. If it is OK, we need
to mention it so that both parties can prepare for that case. If it's
not OK, we should document it as such.
2331-2333, 2396-2397, and 2427-2428: what does it mean to have a logout
request expire? Does that mean that the SP shoud not log the user out
any further? This makes no sense to me. I think that this is supposed
to refer to the original NotOnOrAfter that was in the original
assertion in order to handle the possible race condition where the
assertion hadn't gotten to the SP yet so the SP should remember the
logout (which is an assertion cancellation) until that time so that if
the assertion is subsequently presented, it should be refused.
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