Hi Tarun, As Aaron mentioned there are less tightly profiled variations of this general flow, like oauth-identity-chaining <https://datatracker.ietf.org/doc/draft-ietf-oauth-identity-chaining/>or rfc8693 <https://datatracker.ietf.org/doc/html/rfc8693> + rfc7523 <https://datatracker.ietf.org/doc/html/rfc7523> together directly, that don't have the same constraint regarding the IDP not issuing access tokens in response to an ID-JAG it issued itself. Perhaps that might meet your needs? Although those are intended for cross domain as well. Honestly, much of this seems like more than is needed for a same idp / same domain case.
On Tue, Feb 3, 2026 at 8:13 PM Tarun Nanduri <[email protected]> wrote: > Dear Aaron, > > I am awaiting your feedback on this. To summarize, > > When an Identity Provider (IdP) does not support Single Sign-On (SSO) due > to the nature of the systems involved, and a user needs to transfer their > session to another application without re-logging in, I feel ID-JAG offers > a secure and seamless solution, providing a smooth user experience. > > The RFC, as stated in previous emails, explicitly prohibits using the > specification within the same IdP. Considering the zero-trust model > typically applied within the same IdP, are we open to modifying the > specification to allow its implementation within such environments? > > Best Regards, > Tarun Nanduri. > > On Fri, Dec 5, 2025 at 8:46 AM Tarun Nanduri <[email protected]> > wrote: > >> Hi Aaron, >> >> Thanks for the response, and pointing me to the Identity Chaining draft. >> However, after looking at it, I don't think it applies to the use-case I >> shared above (please feel free to correct here). It looks like it's >> designed for cross-domain scenarios* whereas the use-case I shared above >> has*, >> >> - Both the clients are in same trust domain >> - We have single authorization server (it's the IdP too) >> >> The challenge we are trying to solve is, >> >> - Client A needs to transfer user session to client B >> - WITHOUT Client A sharing its access token with client B (security >> risk due to token exposure, invalid audience, unnecessary privileges etc.) >> - Both clients trust the same IdP >> >> This is why we're intending to use RFC8693, but it still requires client >> A to send access token (after token exchange) to client B which creates >> exposure we're trying to avoid. The ID-JAG pattern (cryptographic proof of >> identity, not a usable token) would be perfect, except the prohibition >> defined in section 8.3 of Identity Assertion draft: >> 8.3. >> <https://www.ietf.org/archive/id/draft-parecki-oauth-identity-assertion-authz-grant-05.html#section-8.3>Cross-Domain >> Use >> <https://www.ietf.org/archive/id/draft-parecki-oauth-identity-assertion-authz-grant-05.html#name-cross-domain-use> >> >> This specification is intended for cross-domain uses where the Client, >> Resource App, and Identity Provider are all in different trust domains. In >> particular, the Identity Provider MUST NOT issue access tokens in >> response to an ID-JAG it issued itself. Doing so could lead to >> unintentional broadening of the scope of authorization. >> My question remains, Can the section 8.3 prohibition be satisfied with >> enough security controls (scope validation, replay prevention etc.) for >> same IdP scenarios, or is it a hard limitation? >> >> Thanks and Regards, >> Tarun Nanduri. >> >> >> On Fri, Dec 5, 2025 at 1:53 AM Aaron Parecki <[email protected]> wrote: >> >>> Hi Tarun, >>> >>> It sounds like what you are looking for is the parent draft of this >>> draft, Identity and Authorization Chaining Across Domains: >>> https://datatracker.ietf.org/doc/draft-ietf-oauth-identity-chaining/ >>> >>> The document that defines the ID-JAG, Identity Assertion Authorization >>> Grant, is a special case of Identity Chaining where both the client and >>> resource have a pre-existing relationship with the same IdP. So I don't >>> view it as a limitation, it's actually an optimization when there is a >>> common IdP. The Identity Chaining draft is the same as this draft except it >>> doesn't specify the input token format or the reason why the client and >>> resource trust the cross-domain JWT issuer. >>> >>> Aaron >>> >>> >>> >>> On Mon, Dec 1, 2025 at 8:11 AM Tarun Nanduri <[email protected]> >>> wrote: >>> >>>> Dear OAuth Working Group & Aaron, >>>> >>>> I would like to provide feedback on the OAuth Identity Assertion >>>> Authorization Grant (ID-JAG) specification, specifically regarding >>>> the prohibition against same-IdP usage. >>>> >>>> Use Case: >>>> >>>> In microservices architectures using the same IdP, there is a >>>> legitimate need for service-to-service identity delegation WITHOUT >>>> sharing access tokens directly: >>>> >>>> - Application A has a user-scoped token >>>> - Application A needs to invoke Application B on behalf of user >>>> - Sharing Token A with Application B creates security risks: >>>> * Token exposure between services >>>> * Replay attacks >>>> * Over-privileged access >>>> * Audience mismatch >>>> >>>> The Gap: >>>> >>>> ID-JAG's assertion pattern solves this perfectly: >>>> - Application A creates a cryptographic identity assertion >>>> - Assertion is audience-bound to Application B >>>> - Application B exchanges assertion for its own token >>>> - No credential sharing between services >>>> >>>> However, the same-IdP prohibition prevents this legitimate use case. >>>> >>>> Suggestion: >>>> >>>> Consider either: >>>> 1. Removing the same-IdP prohibition with appropriate security guidance >>>> 2. Adding an exception for service-to-service delegation scenarios >>>> 3. Providing guidance on how to achieve this pattern within the same IdP >>>> >>>> RFC 8693 (Token Exchange) doesn't fully address this use case as it >>>> requires sending the actual token (subject_token), which is what we're >>>> trying to avoid. >>>> >>>> Security Considerations: >>>> >>>> With zero-trust validation, same-IdP assertions can be just as secure >>>> as cross-IdP: >>>> - Validate assertion issuer is authorized >>>> - Apply fresh authorization policy evaluation >>>> - Enforce audience restrictions >>>> - Use short-lived assertions >>>> - Implement scope intersection, not broadening >>>> >>>> Would appreciate the working group's consideration of this use case. >>>> >>>> Best regards, >>>> Tarun Nanduri. >>>> >>> _______________________________________________ > OAuth mailing list -- [email protected] > To unsubscribe send an email to [email protected] > -- _CONFIDENTIALITY NOTICE: This email may contain confidential and privileged material for the sole use of the intended recipient(s). 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