Authorization Server: DPoP Support (SEP-1932) - #396
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This was referenced Jul 7, 2026
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…l#370) Follow-up on the DPoP client PR (shared foundation: createAuthServer DPoP core + dpopProof/dpopToken helpers). Adds an authorization-server scenario testing DPoP (SEP-1932 / RFC 9449): metadata (dpop_signing_alg_values_supported present, asymmetric-only), token binding (cnf.jkt + token_type=DPoP), and no-proof enforcement when dpop_bound_access_tokens is advertised. Probes a live AS via authorization_code + PKCE (auto-follows a direct redirect, falls back to an interactive callback) and returns four sep-1932-as-* checks (compliant run + four one-defect-isolation misbehaving configs). - authorization-server/dpop.ts (+ acceptance test, spec-references). - dpopToken: adds readTokenBinding() (reads token_type + cnf.jkt back out of a token response) — introduced here because this scenario is its only consumer. Depends only on the shared DPoP foundation; independent of the server PR. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
negotiateProofAlg fell back to ES256 for a present-but-non-array dpop_signing_alg_values_supported (e.g. the string "RS256"), contradicting its docstring and risking a token-binding mis-score for that malformed shape. Treat a present-but-non-array value as null (SKIP), like a non-empty list with no supported alg; only an absent/empty list still falls back to ES256. Defensive against malformed metadata; not independently exercised by a fixture (would need a malformed-metadata AS option), consistent with the htu-strip defensive fixes. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The round-4 non-array guard carved out `null` (advertised !== null), so metadata with "dpop_signing_alg_values_supported": null passed the support gate (which only tests === undefined), skipped the guard, and fell through to the ES256 fallback — the exact binding mis-score the fix targeted. Extract the negotiation to an exported pure function negotiateProofAlg(advertised) and treat ANY present-but-non-array shape (string, null, number, object) as malformed → null (SKIP). Only an empty array still falls back to ES256. Correct the docstring (an absent field never reaches here — the support gate SKIPs upstream). Add unit tests for every shape (array / empty / no-overlap / string / null / number / object), pinning the fix against a silent refactor regression. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Broaden the negotiateProofAlg fallback test to also assert undefined → ES256
and correct its title ("empty array or absent field") — the contract covers
both, though absent is gated upstream in the scenario.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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@Michito-Okai - I believe the conflicts are resolved. |
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Overview
Conformance tests for DPoP support (SEP-1932 / RFC 9449) on the authorization server side.
Builds on the shared DPoP test helpers introduced in the client PR (#394, merged).
Closes #370.
What it tests
That an authorization server correctly advertises and implements DPoP. The scenario drives a real authorization-code + PKCE flow and checks the server:
dpop_signing_alg_values_supportedin its metadata (RFC 9449 §5.1).none, no symmetric algorithms.cnf.jktmatches the presented proof,token_type: DPoP).The scenario is support-gated: an authorization server that doesn't advertise DPoP is not a DPoP server, so it's skipped rather than failed.
Each check is proven to pass (compliant example authorization server) and to fail (misbehaving configurations), with an automated acceptance suite.
Scope
Authorization-server behaviour only — metadata and token issuance. Proof validation at the resource is covered by the MCP-server PR (#369); client presentation by the client PR (#394).
Notes