1. Concepts

The question DIP answers

Before an agent takes an action, DIP answers one question: is this action permitted, under a specific authority, right now? It answers ALLOW or DENY, and nothing else.

The parts

Term	Meaning
Authority	A signed declaration of what an agent may do: which actions, which resources, up to what amount, in which currencies, and during which dates. Versioned and immutable.
Trust root	The public key of a party whose signatures the system accepts (an issuer, the engine, the evidence signer, an approver).
Request	What an agent wants to do: the actor, the operation, the resource, the amount, and the authority it claims.
Decision	The engine's signed answer, ALLOW or DENY, with reason codes and the checks it ran.
Approval	A human's signed decision on a specific request. Routes a case to a person. It never authorizes by itself.
Execution	Running the action through the protected boundary. Only a valid ALLOW decision can start it.
Evidence	A signed record of what was asked, decided and done. Records form a hash chain, so any change or deletion is detectable.

The flow

authority ──▶ request ──▶ authorize ──▶ ALLOW? ──▶ execute ──▶ evidence
                              │              │
                              │              └── DENY ──▶ evidence (refusal recorded)
                              │
                        needs approval? ──▶ approval (a person decides) ──▶ re-authorize

1. An issuer publishes an authority.
2. The agent sends a request.
3. The engine checks the request against the authority and returns a signed decision.
4. On ALLOW, the boundary executes the action once and records the attempt.
5. Every step, including refusals, is written to the evidence chain.

Why it is built this way

• Two outcomes only. Authorization is ALLOW or DENY. There is no "maybe".
• Fail closed. Malformed input is refused. A missing or unverifiable signature is a refusal.
• Single use. A decision authorizes one execution. A retry needs a new decision.
• Independent verification. Anyone can check the evidence with the public keys, without trusting the server.

Next

Run the example in 02-run-the-example.md to see each part work.