Cryptographically Verifiable Actor Chains for OAuth 2.0 Token Exchange#

A Prasad, Ramki Krishnan, Diego Lopez (Telefónica), Srinivasa Addepalli (individual, SPICE WG)

• Why: Multi-hop service-to-service and agentic workflows need delegation-path continuity: RFC 8693 allows nested act claims but prior actors are informational only — nothing today cryptographically proves the chain of token exchanges that produced a token. That's the auditability gap for agent-driven API access.
• What: Six actor-chain profiles for RFC 8693 token exchange — Declared vs Verified, each in Full/Subset/Actor-Only disclosure variants — trading off visible chain-based authorization, cryptographic accountability, auditability, privacy, and long-running workflow support. sub, act, may_act semantics are preserved; plain RFC 8693 impersonation-shaped outputs remain valid but sit outside the profile family (from abstract only).
• How: Profiling of token-exchange outputs such that the delegation path is preserved and validated across successive exchanges, with per-profile processing rules (from abstract only).
• Where applicable: Same-domain and cross-domain delegation chains in service meshes and agentic workflows. Status caveat: presented in SPICE, but the individual draft (draft-mw-spice-actor-chain-05) has since expired and been replaced by draft-mw-oauth-actor-chain — the work is alive but moving to the OAuth WG; expect the successor document when tracking it.