MCP Broker Security Model

Authentication

Short-Lived Access

Authenticate callers with OAuth or workload identity and avoid static API keys.

Proof

Request Binding

Protect sensitive operations with request-level proof to reduce replay risk.

Operations

Audit and Revocation

Log sensitive actions and keep fast revoke-and-recover paths ready.

Required Controls

1. Use OAuth device flow for local MCP login.
2. Use workload identity for server-to-server callers.
3. Use request proof for lease and other sensitive operations.
4. Keep tokens short-lived and limited to the task.
5. Record audit events for all sensitive broker actions.

Lease Request Proof

Example proof payload for sender-constrained requests.

{
  "proof_type": "dpop_jwt",
  "dpop_jwt": "<signed_jwt>",
  "nonce": "nonce-create-0001"
}

Token Lifecycle

1. Use short-lived access tokens.
2. Keep tokens in memory where possible.
3. Rotate signing material regularly.
4. Revoke and re-issue immediately on suspicion.
5. Audit all sensitive operations.

Integration Guidance

• Classify non-retryable errors (`invalid_argument`, `permission_denied`).
• Use exponential backoff for transient failures (`unavailable`).
• Validate all critical auth and lease flows in E2E before production.