On 07/01/2020 00:22, Filip Skokan wrote: > 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. > Could you expand a bit on the second sentence?
Alternative suggestion: The AS MUST validate the request in the same way as at the authorization endpoint, or complete the request validation at the authorization endpoint. Vladimir > 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 > <mailto: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 > <mailto:neil.mad...@forgerock.com>> > *Date: *Monday, January 6, 2020 at 6:29 AM > *To: *Brian Campbell <bcampb...@pingidentity.com > <mailto:bcampb...@pingidentity.com>> > *Cc: *"Richard Backman, Annabelle" <richa...@amazon.com > <mailto:richa...@amazon.com>>, Nat Sakimura <n...@sakimura.org > <mailto:n...@sakimura.org>>, Dave Tonge <dave.to...@moneyhub.com > <mailto:dave.to...@moneyhub.com>>, Torsten Lodderstedt > <tors...@lodderstedt..net <mailto:tors...@lodderstedt.net>>, oauth > <oauth@ietf.org <mailto: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 > <mailto: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 > <mailto: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 > <mailto:oauth-boun...@ietf.org> on behalf of > torsten=40lodderstedt....@dmarc.ietf.org > <mailto:40lodderstedt....@dmarc.ietf.org>> wrote: > > Hi Filip, > > > On 31. Dec 2019, at 16:22, Filip Skokan > <panva...@gmail.com <mailto: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 <mailto: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 <mailto:OAuth@ietf.org> > https://www.ietf.org/mailman/listinfo/oauth >
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