Canonical: https://docs.cascadeauth.com/overview/ Applies to: AAC platform · developer beta Documentation revision: 42797a46037edf5ee429e481115b69646b5a7900 --- # Overview ## What AAC is for AAC lets a network of AI agents — tens, hundreds or thousands of them, inside one organisation and across organisations — carry **delegated authority** from agent to agent, with provable identity, local verification and auditable receipts. Authority starts with a decision your own application makes. Your application authenticates the person, or obtains the approved service identity, and decides what work it may authorize under your policy. AAC binds that decision into a signed chain every later agent can check. In one chain: 1. **A person authorizes work.** The originating agent's sidecar **mints the root token**: a root block carrying your tenant id, a hash of the identity your application supplied, a hash of the originating workload's identity, the root key id, the signature algorithm and the issue time — signed with your tenant's **root signing key**. The sidecar then appends the first caveat, the class of action. 2. **Each agent that passes the work on attenuates the token.** It appends a caveat that cannot widen what may be done, can only shorten the expiry, and names the holder allowed to act next. Its sidecar signs a **proof of possession** with its identity key, showing that the workload presenting the certificate really holds the private key behind it. 3. **The receiving sidecar verifies locally**: the root signature against the originating tenant's published root public key, then the caveat chain and its conditions, then the presenter's proof of possession, its identity against the caveat that named it, and the replay check. 4. **The last agent** — the one with nobody left to call — finishes the work and signs a **receipt** that can be checked afterwards. Two properties follow. **Authority never widens as it travels.** A later hop's limits may stay the same or become tighter; no operation produces a child token permitting more than its parent. Holder binding is a separate control: each hop also names who may act next, so the same chain does not become usable by a different agent. **Every chain expires.** No chain outlives 24 hours from the moment its root was signed. Work that runs longer takes a fresh authorization at a business checkpoint rather than a longer chain. ### What local verification buys, and what it does not Each hop is checked with local computation against trust material the sidecar already holds: the root signature, the certificate chain, the proof of possession and the chain's own conditions. Nothing on the request path asks the earlier agents, or their identity providers, to re-authorize the hop — the person signs in once, at the start, and the chain carries that decision onward. That is what keeps authority affordable as a network grows: a chain crossing ten organisations makes no fan-out of token-introspection calls to ten identity providers. Three limits are worth knowing before you design around it: * **Trust material is cached, and a cache can miss.** Sidecars refresh published root keys and CA certificates in the background, but a missing entry or a freshness deadline can make that refresh happen while a request is being verified — and verification **fails closed** when required trust material is unavailable or too stale. * **A copied chain is not usable on its own, but a compromised agent is a different matter.** Whoever copies a chain still has to present a valid proof of possession as the holder the chain names, and still meets the replay checks. An attacker who has compromised an authorized agent is already inside those controls — which is why the business limits you put in caveats, not identity alone, are worth setting. * **The shared durable replay profile adds a dependency** — a store your tenant operates — on the path of every received request. The Basic profile keeps replay state in the sidecar's own memory instead; see [replay protection profiles](https://docs.cascadeauth.com/sidecar/integration/#replay-protection-profiles). ### What a receipt proves A receipt is your tenant's signed statement that an agent reported a particular outcome. It is not by itself proof that the real-world action happened, and checking one months later is not automatic: it needs the trust material published at the time, an observation time you trust independently, and your own workflow records. [Keys and certificates](https://docs.cascadeauth.com/overview/keys-and-certificates/) says what to keep; [Verify terminal evidence offline](https://docs.cascadeauth.com/sidecar/operations/#verify-terminal-evidence-offline) has the procedure. ## How a delegated workflow works ```text Originator application | mint-root: choose authority and submit a task v Sidecar A --authenticated /invoke--> Agent A | Agent A returns forward(destination, narrower predicates) | signed chain + proof of the presenting workload v Sidecar B --authenticated /invoke--> Agent B | Agent B returns settle or refuse v settle -> signed settlement evidence refuse -> refusal result (no terminal attestation) ``` Sidecar B checks authority, identity, recipient and replay protection before calling Agent B. Each agent still decides whether the requested business action is appropriate. A `forward` decision can narrow authority, never broaden it. The local example uses one sidecar twice; the two-agent example shows the same flow with separate processes. Optional central telemetry correlates selected metadata; full local evidence stays with the tenant. | Term | Meaning and configuration | |---|---| | Tenant | The organization/project boundary assigned a `tnt-` ID; `tenant.id` | | Workload / agent | Your running application, identified by one concrete SPIFFE ID; `agent.spiffe_id` | | Sidecar | The process beside a workload that verifies and carries authority | | Root-signing key | Starts an authority chain; `tenant.signing_key_file` or a configured remote signer | | SVID | An X.509 certificate binding a workload SPIFFE identity to its public key; `agent.svid_cert_file` | | DPoP | Proof signed by the presenting workload, binding authority to the exact HTTP request; uses the local SVID key | | Class of action | A named initial authority profile selected at mint time; `classes_of_action` | | Predicate | A restriction such as `action`, `amount_max`, `task_ref` or expiry | | Holder audience | The workload identity permitted to hold a chain step; class and attenuation audience constraints | | Destination | A named peer URL, exact recipient identity and limits; `destinations` | | Attenuation | Creating a child authority step with equal or narrower permissions | | Continuation authority | A short-lived right to continue a verified inbound task for the same pair/task/presenter | | Settle / terminal attestation | An agent finishes a task and its sidecar signs the terminal evidence using a distinct key | | Pairing secret | Authenticates calls between one sidecar and its paired agent; `sidecar.agent_invoke_auth.secret_file` | | Replay protection | Rejects repeated presenting proofs; `replay_protection` | | A2A retry state | Retains dispatch outcomes so the same dispatch ID/body can be retried without executing twice; `a2a.egress_idempotency` | [Run the reservation example](https://docs.cascadeauth.com/get-started/) or [integrate your own agents](https://docs.cascadeauth.com/sidecar/integration/).