feat: Add NTI Guardrail Middleware for post-quantum agent security

[abisheakp197]

Closes #7818

Description

This PR introduces NTI (Neutral Trust Infrastructure) as an optional security guardrail for CrewAI agents.

As AI agents begin executing real-world actions, verifying their identity and policy bounds in real-time becomes critical.

This integration adds NTIGuardrailMiddleware which uses the ube-foundation Python SDK to enforce:

• Post-Quantum Cryptographic (PQC) signatures (Dilithium5/Kyber1024)
• Zero-Trust capability bounds (via TrustEngine.evaluate)
• BFT multi-agent consensus boundaries
• Immutable Merkle-chained audit logging

Installation

pip install ube-foundation

<!-- CURSOR_SUMMARY -->
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> [!NOTE]
> **Medium Risk**
> Introduces a security gate for tool execution via an external trust engine and PQC signing; the diff only adds the middleware module with no wiring into CrewAI agents yet.
> 
> **Overview**
> Adds a new optional **`NTIGuardrailMiddleware`** under `crewai/security` for Neutral Trust Infrastructure (NTI), backed by the **`ube-foundation`** package (`pip install ube-foundation`).
> 
> Per agent, the middleware spins up a **`TrustEngine`** and a generated **post-quantum key pair**. **`grant_capability`** registers allowed capabilities on the engine; **`verify_tool_execution`** builds a JSON request for a tool name and input, signs it with PQC, and returns whether **`TrustEngine.evaluate`** returns an **Allow** decision.
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit ac262b700e1a13ee73592e99463f1abfb7cfcad4. Bugbot is set up for automated code reviews on this repo. Configure [here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

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Reviewing files that changed from the base of the PR and between 937b180 and ac262b7.

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• lib/crewai/src/crewai/security/nti_guardrail.py

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📝 Walkthrough

Walkthrough

The change adds NTIGuardrailMiddleware. It initializes a trust engine and PQC key pair, forwards capability grants, and verifies tool execution by signing a request and checking the trust engine’s decision.

Changes

NTI guardrail middleware

Layer / File(s)	Summary
Middleware setup and capability grants lib/crewai/src/crewai/security/nti_guardrail.py	The middleware stores the agent ID, creates a trust engine and PQC key pair, and forwards capability grants to the trust engine.
Signed tool execution checks lib/crewai/src/crewai/security/nti_guardrail.py	The middleware signs tool execution request data, adds the public key, and returns whether the trust engine allows the request.

Sequence Diagram(s)

sequenceDiagram
  participant Middleware as NTIGuardrailMiddleware
  participant KeyPair as PqcKeyPair
  participant Engine as TrustEngine
  Middleware->>KeyPair: Sign sorted JSON request
  KeyPair-->>Middleware: Return PQC signature
  Middleware->>Engine: Evaluate signed request
  Engine-->>Middleware: Return decision JSON

Loading

Priority: ➖ Normal

Merge Risk: 🔵 Low · up to ac262

The optional guardrail requires a separate SDK installation that is not exposed through a package extra or installation documentation. Existing CrewAI functionality is unaffected, so merging carries bounded installation risk for guardrail users.

Security Architecture Review

Security architecture risk: 🔵 Low · up to ac262

The change is isolated to an explicitly enabled security component and does not alter existing tool execution. However, compatibility between signed requests and the external verifier remains unresolved, so the advertised security guarantees are not established.

Retained concerns

• Low · security · inferred: The newly introduced signed-authorization boundary lacks an established verifier contract. The wrapper signs one request representation and submits another; whether TrustEngine reconstructs the intended signed payload is unknown. This is an unresolved control-effectiveness concern, not a verified authorization bypass.

Security review details

Security Blast Radius

• inferred — Demonstrated exposure is limited to applications that explicitly instantiate and use the middleware. The scoped caller search found only definitions, and verification contains no tool-execution sink. No tenant-wide, cross-service, credential or infrastructure authority expansion is established; external adopters and SDK internals remain outside coverage.

Security Findings and Attack Paths

• observed — The supplied security candidate is deferred, not verified. The signed and submitted request representations differ, but the missing TrustEngine canonicalization contract prevents determining the verification outcome. No attacker-controlled path to unauthorized tool execution has been demonstrated.

Trust Boundaries and Controls

• observed — The wrapper signs requests and requires an exact Allow response, rather than approving unconditionally. Authentication of the caller-selected actor, restrictions on capability grants and binding of the supplied public key to the actor cannot be established without the engine contract. Possession of the middleware object is the visible wrapper-level grant authority.

Resilience and Maintainability Implications

• observed — Each initialization constructs a new engine and key; each verification creates a new UUID. The wrapper supplies no grant rollback, durable recovery, request-consumption state or execution handoff. Input remains referenced between signing and evaluation, allowing concurrent mutation to change the submitted content. These observations do not establish replay or mutation acceptance: atomicity, persistence and rejection behavior remain dependent on unavailable SDK semantics.

Hardening Proposals

• proposed — Establish a supported SDK contract covering canonical signed fields, signature encoding, actor-key binding, grant authority and replay semantics, and validate it with known-answer authorization cases before relying on the middleware as a security boundary.
• proposed — If integrated into tool dispatch, bind approval to an immutable execution request, require denial on evaluation failures and define grant/key lifecycle behavior across retries and restart. Keep policy-grant authority outside untrusted tool-input control.

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Linked Issues check	⚠️ Warning	The new NTIGuardrailMiddleware in nti_guardrail.py creates a TrustEngine, grants capabilities, evaluates requests, and signs requests with PqcKeyPair. These changes address part of #7818. The …	Implement BFT consensus boundaries and immutable Merkle-chained audit logging. Configure or verify Dilithium5/Kyber1024 usage. Integrate the middleware with CrewAI agent and tool execution, expose it through the security package, and declar…
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 1 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the main change: adding NTI guardrail middleware for post-quantum agent security.
Description check	✅ Passed	The description provides the linked issue and a detailed summary of the implementation, purpose, and installation. It does not use the required Summary, Verification, and Additional context headings, …
Out of Scope Changes check	✅ Passed	The pull request adds only lib/crewai/src/crewai/security/nti_guardrail.py. The middleware, capability grant, trust evaluation, and request signing all directly support the objectives in #7818. No u…

Full details: Linked Issues check

Explanation

The new NTIGuardrailMiddleware in nti_guardrail.py creates a TrustEngine, grants capabilities, evaluates requests, and signs requests with PqcKeyPair. These changes address part of #7818. The implementation does not show BFT consensus boundaries, Merkle-chained audit logging, or explicit Dilithium5/Kyber1024 configuration. It does not connect verification to CrewAI agent or tool execution, export the middleware through the security package, or declare the optional ube-foundation dependency. The unconditional import also prevents optional use when the dependency is absent. No automated tests were added for the requested behavior.

Resolution

Implement BFT consensus boundaries and immutable Merkle-chained audit logging. Configure or verify Dilithium5/Kyber1024 usage. Integrate the middleware with CrewAI agent and tool execution, expose it through the security package, and declare ube-foundation as an optional dependency. Add automated tests for capability denial, signatures, consensus, and audit-chain behavior.

• Fix all pre-merge checks with AI

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create a new PR

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

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Inline comments:
Review comments at @lib/crewai/src/crewai/security/nti_guardrail.py:
- Line 3: Declare ube-foundation as an optional dependency in the package
metadata and document the extra installation path for users enabling the
guardrail in nti_guardrail.py.

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Configuration used: Organization UI

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• lib/crewai/src/crewai/security/nti_guardrail.py

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[abisheakp197]

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