Hybrid PQC Signing

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Hybrid Post-Quantum Cryptographic (PQC) Signing

AgentV v1.6.2 introduces support for Hybrid Post-Quantum Cryptographic (PQC) Signing. This protocol is designed to protect industrial forensic traces against emerging quantum computing threats while maintaining strict data privacy through the Zero-Exposure Signing (ZES) pattern.

This guide is intended for Auditors, Integrators, and Evaluators who need to ensure the long-term non-repudiability of agentic evaluation results.

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🏗️ Architecture

The hybrid protocol combines classical elliptic curve cryptography with modern lattice-based algorithms, ensuring that the system remains secure even if one of the layers is compromised.

1. Classical Layer: Ed25519 (SHA-512 + Curve25519) - Used for high-performance, universally compatible signing.
2. Post-Quantum Layer: ML-DSA-65 (Module-Lattice-based Digital Signature Algorithm) - Aligned with NIST’s FIPS 204 standard for quantum resistance.
3. Hybrid Binding: Both signatures are mathematically bound to the same Verification Certificate (VC) v3.0.0 and stored in the provenance_chain.

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🧬 Zero-Exposure Signing (ZES) Protocol

To maintain the privacy of industrial evaluation data, AgentV implements the Zero-Exposure Signing (ZES) pattern. This ensures that raw traces, trajectories, and sensitive logs never leave the project’s security jail.

The ZES Flow

1. Generate Manifest (VC v3) The harness assembles the run_manifest.json containing the trace hash and forensic evidence ledger.

2. Compute SHAKE-256 Digest The manifest is hashed locally using SHAKE-256. This creates a fixed-length (32-byte) cryptographic condensation of the data.

3. Secure Transmission Only the resulting 32-byte digest is transmitted to the PQC provider (CycleCore) along with your API Key. The raw trace data never leaves your environment.

4. Remote Signing The provider signs the digest using the ML-DSA-65 algorithm and returns the signature hex.

5. Seal Certificate The signature is appended to the provenance_chain and the Verification Certificate is sealed for final audit.

ZES ensures that even if the PQC provider is compromised, your proprietary agent trajectories remain private as they were never shared.

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⚙️ Configuration (Environment Variables)

Enable and configure Hybrid PQC using the following parameters. You can set these in your .env file.

Variable	Default	Description
PQC_ENABLED	false	Set to true to activate the hybrid signing pipeline.
PQC_PROVIDER	cyclecore	The cryptographic provider (e.g., cyclecore).
PQC_STRICT_MODE	false	If true, fails evaluation if PQC signing fails.

Variable	Default	Description
CYCLECORE_API_KEY	(None)	Your ZES API key (Required for remote signing).
CYCLECORE_IDENTITY_ID	default	The identity name for the PQC signature.

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🛠️ Troubleshooting

Common CycleCore API Errors

Error Symptom	Potential Cause	Resolution
Authentication Failure	Invalid or expired CYCLECORE_API_KEY.	Check your environment variables and CycleCore dashboard.
Rate Limit Exceeded	Too many concurrent signing requests.	Implement ADAPTER_RETRY_DELAY or contact support for higher limits.
Connection Timeout	Network/Firewall blocking egress to the PQC provider.	Ensure your host can reach the CycleCore API endpoints.
ImportError: cyclecore-pq	The cyclecore-pq package is missing.	Run pip install cyclecore-pq or check your pyproject.toml.

Verification Failures

• Signature Mismatch: Ensure the PQC_IDENTITY_ID used during signing matches the one configured during verification.
• Hash Inconsistency: If the local SHAKE-256 digest differs from the one recorded in the manifest, verification will fail automatically to prevent tampering.

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⚖️ NIST Alignment

The Hybrid PQC implementation is explicitly aligned with NIST AI-100-1 and NIST FIPS 204, providing a non-repudiable bridge between raw evaluation data and regulatory-grade compliance reports.