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Sigil Vault is the just-in-time (JIT) credential broker for the Sigil ecosystem. It ensures that autonomous agents can use external credentials — API keys, cloud secrets, MPC co-signatures — without ever possessing them. Vault is not a secrets manager. It does not store or custody secrets. It is a deterministic capability broker: it intercepts agent requests, validates a cryptographic Intent Attestation from Sigil Sign, fetches a short-lived credential from your own infrastructure at request time, injects it into the outbound request, and purges it from memory. Doctrine: Agents never possess credentials. Vault never stores them. Every capability release requires cryptographic proof of authorization.

The Enterprise Fragmentation Problem

Most enterprises operate with decades of accumulated systems: on-premises databases, cloud infrastructure that was lifted-and-shifted without modernization, and a long tail of SaaS tools — each with its own credential model. Autonomous agents cannot tap into these systems in a unified way without a credential injection layer that bridges the gap between the agent’s reasoning context and the access controls each system requires. Vault solves this structurally:
  • Agents never receive standing credentials — no agent holds a long-lived API key or cloud secret. Every request is gated by a cryptographic Intent Attestation before any credential is released.
  • Any credential backend, one integration — Vault abstracts across HashiCorp Vault, AWS Secrets Manager, AWS STS, Azure Key Vault, GCP Secret Manager, and environment variables. Your agents call one proxy; Vault handles the fragmented backend.
  • Legacy systems gain agent-safe access — systems that were never designed for autonomous AI access (internal databases, enterprise SaaS, healthcare platforms, financial APIs) can be safely surfaced to agents through Vault’s attestation-gated injection model.
  • No organizational change required — agents route through Vault’s local proxy. Your existing credential infrastructure stays in place. No migration, no re-architecture.
This is the missing integration layer for enterprises deploying agents into fragmented, legacy-heavy environments.

How It Works

Vault operates as a localhost MITM TLS proxy that sits between your agent and external services:
  1. Agent sends request — the agent makes a normal HTTPS call through Vault’s proxy (127.0.0.1:10255), attaching its Intent Attestation from Sigil Sign.
  2. Attestation gate — Vault validates the Ed25519 JWT signature, claims, expiry, and JTI (replay prevention). Invalid or missing attestations are hard-rejected. No fail-open path exists.
  3. Credential fetch — Vault requests a short-lived, scoped credential from your backend (HashiCorp Vault, AWS Secrets Manager, AWS STS, Azure Key Vault, GCP Secret Manager).
  4. Injection and forwarding — Vault injects the real credential into the outbound request, strips the attestation header, and forwards via real TLS to the upstream service.
  5. Audit and purge — the credential is zeroed from memory. The event is appended to a hash-chained audit log linking Intent Attestation to capability release to execution outcome.
The agent never sees the real credential. The credential never persists in Vault.

Supported Backends

Vault fetches credentials on-demand from client-owned infrastructure:
BackendKindCredential type
HashiCorp Vaulthashicorp-vaultDynamic secrets, KV, PKI
AWS Secrets Manageraws-secrets-managerStored secrets
AWS STSaws-stsTemporary session credentials
Azure Key Vaultazure-key-vaultSecrets, keys, certificates
GCP Secret Managergcp-secret-managerSecret versions
Environment variablesenvStatic values (dev/test only)

How It Relates to the Stack

Vault extends Sigil Sign’s authorization model from on-chain execution to off-chain credential access. The flow is:
Agent Intent
  → Sigil Sign (evaluate warranty.md policy)
  → Intent Attestation JWT
  → Sigil Vault (verify attestation, fetch credential)
  → Inject credential into outbound request
  → External service (Stripe, OpenAI, cloud APIs)
Without Vault, Sigil governs EVM transactions. With Vault, Sigil governs any authenticated external call — API keys for Stripe, OpenAI, Salesforce, database credentials, cloud platform tokens, internal enterprise systems. For enterprises with fragmented or legacy infrastructure, Vault is the bridge that makes those systems agent-accessible without exposing credentials to the agent’s reasoning context or requiring re-architecture of existing backend systems.

Getting Started

Sigil Vault is in active development. The architecture is finalized and implementation is underway. The steps below describe the MVP operator workflow.

Step 1: Install Vault

# From source (Rust 1.78+)
cargo install --path sv-cli

Step 2: Initialize and add a trust anchor

# Initialize the local database
sigil-vault init

# Add your Sigil Sign instance's signing key as a trust anchor
sigil-vault trust add --fingerprint "sha256:<hex>" --kid "<kid>"
The trust anchor tells Vault which signing key to accept when validating Intent Attestations. Use the kid and fingerprint from your Sigil Sign instance’s GET /.well-known/jwks.json endpoint.

Step 3: Register an agent

sigil-vault agents create --name "agent-prod-1"
# Returns an agent token — store it securely
The agent uses this token in its Proxy-Authorization header to authenticate with Vault’s proxy.

Step 4: Add a credential backend

sigil-vault backends add --name "hashi-prod" --kind "hashicorp-vault" \
  --options vault_addr=https://vault.internal:8200,auth_method=approle

Step 5: Create a route

Routes bind an agent to a host pattern and a credential backend:
sigil-vault routes add --agent-id "<id>" --host "api.openai.com" \
  --path "/v1/*" --backend "hashi-prod"
When the agent makes a request to api.openai.com/v1/*, Vault intercepts it, validates the attestation, fetches the credential from hashi-prod, and injects it.

Step 6: Point your agent at the proxy

export HTTPS_PROXY=127.0.0.1:10255
export HTTP_PROXY=127.0.0.1:10255
Your agent now routes all traffic through Vault. High-risk requests require an X-Sigil-Attestation header containing a valid JWT from Sigil Sign.

Step 7: Verify the audit trail

sigil-vault audit tail     # Stream recent events
sigil-vault audit verify   # Verify hash chain integrity

Security Model

  • Zero fail-open paths — missing, invalid, expired, or replayed attestations are hard-rejected (403). Unknown or revoked agent tokens are rejected. Backend timeouts return 504, never a blind passthrough.
  • No standing privileges — credentials are fetched on-demand and zeroed from memory after injection. No credential persists in Vault between requests.
  • Hash-chained audit log — append-only JSONL linking Intent Attestation to capability release to execution outcome. Cryptographically verifiable chain integrity via sigil-vault audit verify.
  • 5-second hard cap — the entire request lifecycle (auth, attestation validation, credential fetch, injection, forwarding) must complete within 5 seconds.
View the Repository: github.com/Sigil-Core/sigil-vault