We've been discussing making the following change to the language The AS SHOULD validate the request in the same way as at the authorization > endpoint. The AS MUST ensure that all parameters to the authorization > request are still valid at the time when the request URI is used. >
This would allow the PAR endpoint to simply stash the encrypted request object instead of decrypting and validating it. All within the bounds of "SHOULD - We’d like you to do this, but we can’t always require it". This supports "light weight PAR" implementation rather than introducing the unnecessary complexity in the form of a second JWKS. Best, *Filip* On Mon, 6 Jan 2020 at 23:00, Richard Backman, Annabelle <richanna= 40amazon....@dmarc.ietf.org> wrote: > The issue isn’t that the PAR endpoint needs access to one specific request > object decryption key that could reasonably be shared across AS endpoints, > but that it actually needs access to the private keys for all encryption > public keys in the JWK set pointed to by the AS’s jwks_uri metadata > property. Since there is no way to designate one particular key as the one > to use for encrypting request objects, clients may reasonably use any > encryption public key in the JWK set to encrypt a request object. As one > example of how this could expose sensitive data to the PAR endpoint, if the > PAR endpoint has all the decryption keys for the keys in the AS’s JWK set, > it would be able to decrypt ID Tokens sent in id_token_hint request > parameters. As more and more use cases develop for encrypting blobs for the > AS, this issue will only get worse. > > > > The PAR endpoint can’t simply stash the encrypted request object, as it is > required to verify the request, according to §2.1: > > > > The AS MUST process the request as follows: > > > > ... > > > > 3. The AS MUST validate the request in the same way as at the > > authorization endpoint. ... > > > > This language needs to be more flexible, IMHO, to allow for lightweight > PAR endpoints that may not have the information or authority needed to > perform all the validation that happens at the authorization endpoint. I > need to think about this more before I can say if it would adequately > address my concerns, but it’d be a good start and makes sense in its own > right. > > > > I think it’s pretty risky for us to base decision on an assumption that no > one is going to need or want to encrypt pushed request objects, > particularly when they’re JWTs, and JWTs have well established support for > encryption, and encrypted JWTs are supported by pass-by-value in OIDC and > draft-ietf-oauth-jwsreq. But if you insist, here are a few examples for why > someone might want to do this: > > 1. The request object is passed by reference, and accessible on the > public Internet. > 2. The request object contains sensitive transaction-related data in > RAR parameters that the client’s authN/authZ stack doesn’t need to have > access to. > 3. The AS requires request object encryption to minimize exposure to > the hosted PAR endpoint service it uses. > 4. #2, but the threat vector is gaps in end-to-end TLS. > 5. Any of the above, but the concern is message integrity, and the AS > requires requested objects to be encrypted for confidentiality and > integrity protection and does not support signed request objects. > > > > – > > Annabelle Richard Backman > > AWS Identity > > > > > > *From: *Neil Madden <neil.mad...@forgerock.com> > *Date: *Monday, January 6, 2020 at 6:29 AM > *To: *Brian Campbell <bcampb...@pingidentity.com> > *Cc: *"Richard Backman, Annabelle" <richa...@amazon.com>, Nat Sakimura < > n...@sakimura.org>, Dave Tonge <dave.to...@moneyhub.com>, Torsten > Lodderstedt <tors...@lodderstedt.net>, oauth <oauth@ietf.org> > *Subject: *[UNVERIFIED SENDER] Re: [OAUTH-WG] PAR metadata > > > > Agreed. > > > > In addition, I'm not sure why the PAR endpoint would need access to the > decryption keys at all. If you're using encrypted request objects then the > PAR endpoint receives an encrypted JWT and then later makes the same (still > encrypted) JWT available to the authorization endpoint. If the PAR endpoint > is doing any kind of decryption or validation on behalf of the > authorization endpoint then they are clearly not in separate trust > boundaries. > > > > -- Neil > > > > > > On 6 Jan 2020, at 13:57, Brian Campbell < > bcampbell=40pingidentity....@dmarc.ietf.org> wrote: > > > > I really struggle to see the assumption that an entity be able to use the > same key to decrypt the same type of message ultimately intended for the > same purpose as an artificial limit. The same general assumption > underlies everything else in OAuth/OIDC (Vladimir's post points to some but > not all examples of such). There's no reason for PAR to make a one-off > exception. And should there be some deployment specific reason that truly > requires that kind of isolation, there are certainly implementation options > that aren't compatibility-breaking. And having said all that, I'm honestly > a little surprised anyone is thinking much about encrypted request objects > with PAR as, at least with my limited imagination, there's not really a > need for it. > > > > > > > > > > > > > > > > > > On Fri, Jan 3, 2020 at 2:43 PM Richard Backman, Annabelle <richanna= > 40amazon....@dmarc.ietf.org> wrote: > > PAR introduces an added wrinkle for encrypted request objects: the PAR > endpoint and authorization endpoint may not have access to the same > cryptographic keys, even though they're both part of the "authorization > server." Since they're different endpoints with different roles, it's > reasonable to put them in separate trust boundaries. There is no way to > support this isolation with just a single "jwks_uri" metadata property. > > The two options that I see are: > > 1. Define a new par_jwks_uri metadata property. > 2. Explicitly state that this separation is not supported. > > I strongly perfer #1 as it has a very minor impact on deployments that > don't care (i.e., they just set par_jwks_uri and jwks_uri to the same > value) and failing to support this trust boundary creates an artificial > limit on implementation architecture and could lead to > compatibility-breaking workarounds. > > – > Annabelle Richard Backman > AWS Identity > > > On 12/31/19, 8:07 AM, "OAuth on behalf of Torsten Lodderstedt" < > oauth-boun...@ietf.org on behalf of torsten= > 40lodderstedt....@dmarc.ietf.org> wrote: > > Hi Filip, > > > On 31. Dec 2019, at 16:22, Filip Skokan <panva...@gmail.com> wrote: > > > > I don't think we need a *_auth_method_* metadata for every endpoint > the client calls directly, none of the new specs defined these (e.g. device > authorization endpoint or CIBA), meaning they also didn't follow the scheme > from RFC 8414 where introspection and revocation got its own metadata. In > most cases the unfortunately named `token_endpoint_auth_method` and its > related metadata is what's used by clients for all direct calls anyway. > > > > The same principle could be applied to signing (and encryption) > algorithms as well. > > > > This I do not follow, auth methods and their signing is dealt with > by using `token_endpoint_auth_methods_supported` and > `token_endpoint_auth_signing_alg_values_supported` - there's no encryption > for the `_jwt` client auth methods. > > Unless it was meant to address the Request Object signing and > encryption metadata, which is defined and IANA registered by OIDC. PAR only > references JAR section 6.1 and 6.2 for decryption/signature validation and > these do not mention the metadata (e.g. request_object_signing_alg) anymore > since draft 07. > > Dammed! You are so right. Sorry, I got confused somehow. > > > > > PS: I also found this comment related to the same question about > auth metadata but for CIBA. > > Thanks for sharing. > > > > > Best, > > Filip > > thanks, > Torsten. > > > > > > > On Tue, 31 Dec 2019 at 15:38, Torsten Lodderstedt < > tors...@lodderstedt.net> wrote: > > Hi all, > > > > Ronald just sent me an email asking whether we will define metadata > for > > > > pushed_authorization_endpoint_auth_methods_supported and > > pushed_authorization_endpoint_auth_signing_alg_values_supported. > > > > The draft right now utilises the existing token endpoint > authentication methods so there is basically no need to define another > parameter. The same principle could be applied to signing (and encryption) > algorithms as well. > > > > What’s your opinion? > > > > best regards, > > Torsten. > > > > _______________________________________________ > OAuth mailing list > OAuth@ietf.org > https://www.ietf.org/mailman/listinfo/oauth > > > *CONFIDENTIALITY NOTICE: This email may contain confidential and > privileged material for the sole use of the intended recipient(s). Any > review, use, distribution or disclosure by others is strictly prohibited... > If you have received this communication in error, please notify the sender > immediately by e-mail and delete the message and any file attachments from > your computer. Thank you.*_______________________________________________ > OAuth mailing list > OAuth@ietf.org > https://www.ietf.org/mailman/listinfo/oauth > > > _______________________________________________ > OAuth mailing list > OAuth@ietf.org > https://www.ietf.org/mailman/listinfo/oauth >
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