Re: [Ace] WGLC for draft-ietf-ace-authz
Just one minor note -- this is a great discussion to see happening! On Tue, Oct 23, 2018 at 04:43:14PM +0200, Ludwig Seitz wrote: > > On 22/10/2018 21:09, Jim Schaad wrote: > > * Section 5.8.2 - If the RS is going to do introspection, can it send some > > type of "Server Busy - try again in xxx" while it does the introspection > > rather than just doing an ack of the request and possibly waiting a long > > time? > > This is probably transport protocol specific, and we were asked not to > link the framework to a specific protocol, thus I don't know if we can > provide guidance here. I think it would be okay to say something like "some transport protocols may provide a way to indicate that the server is busy and the client should retry after an interval; this type of status update would be appropriate while the server is waiting for an introspection response". Which does provide guidance, but in a non-normative fashion that does not require or prohibit any given transport protocol. -Ben ___ Ace mailing list Ace@ietf.org https://www.ietf.org/mailman/listinfo/ace
[Ace] FW: draft-ietf-oauth-pop-key-distribution-04
I submitted an update of the PoP key distribution document to get it in sync with what is happening with the ACE OAuth framework. Ciao Hannes From: Hannes Tschofenig Sent: Tuesday, October 23, 2018 2:19 PM To: oauth Subject: draft-ietf-oauth-pop-key-distribution-04 Hi all, I refreshed the PoP key distribution document today, see https://tools.ietf..org/html/draft-ietf-oauth-pop-key-distribution-04, in an attempt to get the document inline with the agreements we made at the Montreal IETF meeting, the Resource Indicators draft, and the work happening in ACE. Thanks to Mike for going through the draft with me and for spotting several copy-and-paste mistakes. Ciao Hannes IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. ___ Ace mailing list Ace@ietf.org https://www.ietf.org/mailman/listinfo/ace
Re: [Ace] WGLC for draft-ietf-ace-authz
> -Original Message-
> From: Ludwig Seitz
> Sent: Tuesday, October 23, 2018 7:43 AM
> To: Jim Schaad ; draft-ietf-ace-oauth-
> au...@ietf.org
> Cc: ace@ietf.org
> Subject: Re: [Ace] WGLC for draft-ietf-ace-authz
>
> Hallo Jim,
>
> thank you for the review! Comments inline.
>
> /Ludwig
>
> On 22/10/2018 21:09, Jim Schaad wrote:
> > * Section 5.8.1 - What is the purpose of creating an identifier for a token?
> > Is this supposed to be used rather than the one from the AS for
> > something like shared secret TLS? Note that this is an unprotected value.
> >
> AFAIK cti is not a mandatory claim of an access token, thus a RS might want
> to create an identifier for tokens that do not have a cti.
Ok - so the client has this cti - what could it use it for?
> > * Section 5.8.1 - If the token is "not valid" is the RS required (i.e. MUST)
> > to try introspection before returning a response if the RS does
> > introspection? The text currently says MAY. If this is really MAY then the
> > text should say that the token is always successfully accepted by the RS.
> >
> I'm not sure I understand the issue. Introspection is optional in
> general, and may be required in specific use cases. If the RS determines
> that the token is not valid on its own, why would it want to do
> introspection on top of this?
The RS has just received a token. The RS wants to validate said token. It can
do it on its own or it can do it with introspection. If it is going to do it
with introspection can it defer this validation until first use or does it need
to do it immediately so it is not going to store an invalid token? It is
possible that an RS is going to both support some tokens and require
introspection on others. In that case it would decide the token was not valid,
but would not necessarily know if it was a legal introspection token.
>
>
> > * Section 5.8.2 - If the RS is going to do introspection, can it send some
> > type of "Server Busy - try again in xxx" while it does the introspection
> > rather than just doing an ack of the request and possibly waiting a long
> > time?
>
> This is probably transport protocol specific, and we were asked not to
> link the framework to a specific protocol, thus I don't know if we can
> provide guidance here.
> > * Section 6 - I am not sure that I agree with the SHOULD NOT in the last
> > paragraph. Think multicast.
> Any suggestions on how to mitigate the issue then? If I issue a token
> bound to a symmetric key for audience {R1, R2, R3}, as soon as R1 got
> this token it can impersonate the client and gain access to R2 and R3.
I am not sure that I think this is an issue that needs to be mitigated. It
needs to be acknowledged, but the assumption would be that if you have three
resource servers that are hosting the same audience they are going to be run by
the same RO and already be coupled. After all it should not matter which of
them you do a GET from, you should get the same answer. Similarly a PUT to one
should propagate to the others so that it is available to all clients.
>
> > * Section 8.6.1 - Is pop still this document or is it Mike's document?
>
> The token type pop is currently not part of
> draft-ietf-ace-cwt-proof-of-possession. I wouldn't argue against putting
> it there.
I would only because it would delay that document. I just could not remember
where if it was there and was too lazy to look.
>
> >
> > * Section 8.9 - The description of reference is wrong.
>
> Can you explain how? I'm not seeing the issue (assuming you mean the
> reference to RFC8126).
Reference This contains a pointer to the public specification of the
grant type abbreviation, if one exists.
This is not about grant types.
>
> >
> > * Section 8.12 - some of these should move to the OAuth parameters
> document?
> >
> These are new claims. We could move them to the params draft, which
> would then become the params and claims draft. I have not strong opinion
> either way.
I have no opinion either way - was just asking.
> > * Registries - I am wondering if we should think about re-writing a couple
> > of the registries. As things stand it appears that the application/ace+cbor
> > content type is being used in 5 or 6 places. It might make more sense to
> > have a registry for all of the CBOR abbreviations that are being used in a
> > single table and have multiple columns for each of the different places
> were
> > the content format is being used. This would make it easier to keep
> > everything constant and can make re-use of integer values easier to see.
> >
> > * Comments on protection of CWT/Token: I am wondering if there needs
> to be
> > any comments on how a CWT is going to be protected. While it is ok to
> use
> > either a symmetric key or a direct key agreement operation for a single
> > recipient without forcing a signature operation to occur. If the token is
> > going to be targeted a single audience hosted on multiple RSs then a
Re: [Ace] WGLC for draft-ietf-ace-authz
Hallo Jim,
thank you for the review! Comments inline.
/Ludwig
On 22/10/2018 21:09, Jim Schaad wrote:
* Section 3.1 - Refresh Token - I don't think that refresh tokens are going
to be strings because binary is more efficient.
This refers to the way it is defined in OAuth. I'll add a word to clarify.
* Section 3.2 - we need to reference TLS 1.3 even if DTLS 1.3 is not yet
available.
Agree.
* Description for Figure 6 - Should the example somehow indicate in the
message that it is going to be an application/ace+cbor content. Also, I
don't know that this is a good example in some ways because this is not a
currently documented profile anywhere.
True. I'll change this to OSCORE.
* Section 5.6.3 - Should the content type for an error response be
application/ace+cbor ?
That makes sense. I'll add a sentence to that effect.
* Section 5.7.1 - Is the content format for a request application/ace+cbor?
I assume it is but that is not documented in this section.I'll add that.
Section 5.8 - bytes arrays or byte strings? I think CBOR uses the latter
Right that slipped through. I'll replace it.
* Section 5.8.1 - What is the purpose of creating an identifier for a token?
Is this supposed to be used rather than the one from the AS for something
like shared secret TLS? Note that this is an unprotected value.
AFAIK cti is not a mandatory claim of an access token, thus a RS might
want to create an identifier for tokens that do not have a cti.
* Section 5.8.1 - Given the change in the OSCORE profile, you might want to
make this an application/ace+cbor structure as well.
Right
* Section 5.8.1 - If the token is "not valid" is the RS required (i.e. MUST)
to try introspection before returning a response if the RS does
introspection? The text currently says MAY. If this is really MAY then the
text should say that the token is always successfully accepted by the RS.
I'm not sure I understand the issue. Introspection is optional in
general, and may be required in specific use cases. If the RS determines
that the token is not valid on its own, why would it want to do
introspection on top of this?
* Section 5.8.2 - If the RS is going to do introspection, can it send some
type of "Server Busy - try again in xxx" while it does the introspection
rather than just doing an ack of the request and possibly waiting a long
time?
This is probably transport protocol specific, and we were asked not to
link the framework to a specific protocol, thus I don't know if we can
provide guidance here.
* Section 5.8.3 - third point - I think that the correct text would be "The
method does not provide timely expiration, but it makes sure that older
tokens will cease to be valid after newer issued tokens are registered with
the RS." My problem is that just issuing tokens is not enough as they may
be going to a different RS for use. This may also need to have some type of
rate limit to issued tokens or making the sequence number be on an
RS/audience basis.
I think the sentence here: "The AS increments this number for each
access token it issues" needs to be ammended to "... for each access
token it issues for this RS".
* Section 6. - The recommendation not to use a shared secret for an audience
which is hosted by multiple servers is interesting. This does require that
a multiple recipient COSE structure be used and it may be worth calling that
out. Also the size of the CWT is going to grow for that. You are also now
losing the low-level authentication and thus a signature wrapping is now
also needed.
Right, I'll extend the paragraph to add this information.
* Section 6 - "Developers MUST" para - May want to add that this can also be
mitigated to some extent by making sure that keys roll over more frequently.
Ok
* Section 6 - I am not sure that I agree with the SHOULD NOT in the last
paragraph. Think multicast.
Any suggestions on how to mitigate the issue then? If I issue a token
bound to a symmetric key for audience {R1, R2, R3}, as soon as R1 got
this token it can impersonate the client and gain access to R2 and R3.
* Section 6.4 - This also applies to sending back some type of identifier
from the RS->C when a token is registered.
That is correct, however the token identifier should be just as opaque
to attackers as the token itself.
* Section 8.6.1 - Is pop still this document or is it Mike's document?
The token type pop is currently not part of
draft-ietf-ace-cwt-proof-of-possession. I wouldn't argue against putting
it there.
* Section 8.9 - The description of reference is wrong.
Can you explain how? I'm not seeing the issue (assuming you mean the
reference to RFC8126).
* Section 8.12 - some of these should move to the OAuth parameters document?
These are new claims. We could move them to the params draft, which
would then become the params and claims draft. I have not strong opinion
either way.
* Section 8.13 - ditto
* Appendix A - para
Re: [Ace] WGLC for draft-ietf-ace-oauth-params
On 22/10/2018 21:09, Jim Schaad wrote:
Here are my WGLC comments:
* I am not sure that I understand what the protocol flow is when JAR is
being used. Is there a potential case where a JWT would be used as the
structure of an OAuth response? If so then is there a problem with defining
cnf in section 4.1?
I wouldn't think so, all the other possible parameters in the
introspection response are defined to be the claims of the token in RFC
7662, cnf is a claim of the token, so I don't see why it shouldn't go
unchanged into the introspection response.
* We need to have a OAuth CBOR integer mapping registry - the items in
section 6 need to be registered into that registry.
That was an oversight. Issue created.
* Review - is the 'cnf' parameter in section 3.2 ok with the OAuth group or
does it need to be renamed as well?
I don't see how this could collide with another meaning. The AS is
responding with the token and additional information about the token
here. This parameter was called 'key' in
draft-ietf-oauth-pop-key-distribution, which felt more phrone to
misunderstandings to me ("what key?").
* Check that cnf in 4.1 is going to be ok with
draft-ietf-oauth-jwt-introspection-response
If I understood it correctly draft only proposes to replace the whole
introspection response with a JWT. I don't see why this shouldn't work
with a CWT as well. No additional data but the JWT/CWT would be sent in
the introspection response, so there should not be any issue with the
cnf claim here.
--
Ludwig Seitz, PhD
Security Lab, RISE
Phone +46(0)70-349 92 51
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