Agent-to-Agent Trust: How to Verify AI Agent Identity

In multi-agent systems, every agent must prove its identity before it can invoke another agent's capabilities or access shared resources — otherwise a single compromised agent can impersonate others and bypass all safety controls. SafeClaw by Authensor enforces agent identity through policy-scoped agent identifiers that are bound to cryptographic audit entries, making impersonation detectable and preventable. Install it with npx @authensor/safeclaw to start enforcing identity-aware gating.

Why Agent Identity Matters

Traditional software authentication uses API keys, JWTs, or mTLS certificates. AI agents introduce a new problem: the agent's identity is often defined by the orchestrator at runtime, and a prompt injection or tool-call hijack can cause one agent to masquerade as another. Without explicit identity verification at the gating layer, the orchestrator becomes a single point of trust failure.

  Agent A ──────┐
                 │   "I am Agent B, allow me deploy access"
  Orchestrator ──┼──▶  SafeClaw Gate ──▶  DENIED
                 │      (Agent A's policy has no deploy perms)
  Agent B ──────┘

SafeClaw's Identity Model

Each agent in a SafeClaw-protected system is assigned a unique agent identifier in its policy file. This identifier is immutable for the lifetime of the policy and is included in every audit log entry:

# safeclaw-policy-deployer.yaml
agent: deployer-prod-us-east
version: "1.0"
identity:
  issuer: "orchestrator-main"
  scope: "production"
  fingerprint: "sha256:a1b2c3d4..."
rules:
  - action: shell_execute
    command: "kubectl apply **"
    decision: allow
  - action: shell_execute
    decision: deny
  - action: file_read
    path: "deploy/**"
    decision: allow
  - action: file_write
    decision: deny

When the gating layer receives an action request, it checks three things:

1. Agent identifier match — The requesting agent's declared ID must match the policy file's agent field.
2. Issuer validation — The orchestrator that spawned the agent must match the identity.issuer field.
3. Policy fingerprint — The loaded policy file's SHA-256 hash must match identity.fingerprint, preventing runtime policy tampering.

Trust Chains in Multi-Hop Systems

When Agent A invokes Agent B, which then invokes Agent C, SafeClaw constructs a trust chain in the audit log:

Audit Entry #1042
  action: agent_invoke
  source_agent: researcher-01
  target_agent: code-writer-02
  issuer: orchestrator-main
  parent_hash: "sha256:f8e7d6c5..."
  entry_hash: "sha256:b4a3c2d1..."

Audit Entry #1043
  action: file_write
  agent: code-writer-02
  path: "src/utils.ts"
  parent_hash: "sha256:b4a3c2d1..."
  entry_hash: "sha256:9e8f7a6b..."

The parent_hash linkage means you can trace any action back through the full invocation chain to the originating agent. Tampering with any entry breaks the hash chain and is immediately detectable.

Preventing Identity Spoofing

Several attack patterns target agent identity:

| Attack | SafeClaw Defense |
|--------|-----------------|
| Prompt injection claiming agent identity | Policy-bound ID checked at gate, not from LLM output |
| Orchestrator impersonation | Issuer field validated against known orchestrator list |
| Policy file swap | Fingerprint mismatch triggers deny-all fallback |
| Replay of old agent credentials | Hash-chain audit detects temporal inconsistency |

The key architectural decision is that agent identity is never derived from the LLM's output. The identity comes from the policy binding established before the agent starts executing, making prompt injection irrelevant to identity verification.

Implementing Agent Trust with SafeClaw

import { createGate, verifyAgentChain } from '@authensor/safeclaw';

// Each agent gets its own gate with identity enforcement
const deployGate = createGate({
  policy: './safeclaw-policy-deployer.yaml',
  identity: { enforce: true, issuer: 'orchestrator-main' }
});

// Before cross-agent invocation, verify the trust chain
const chainValid = await verifyAgentChain({
  source: 'researcher-01',
  target: 'deployer-prod-us-east',
  auditLog: './audit/chain.log'
});

if (!chainValid) {
  throw new Error('Agent trust chain verification failed');
}

SafeClaw works with both Claude and OpenAI agent frameworks, and the identity model is provider-agnostic. The 446-test suite covers identity verification edge cases including partial chain corruption, concurrent agent spawning, and orchestrator failover scenarios.

Cross-References

• Multi-Agent Safety Architecture
• Hash-Chain Audit Logs Deep Dive
• Zero Trust Agent Architecture
• Multi-Agent Lateral Movement Threat