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securitycritical PriorityID: pqc-hybrid-mlkem768-tls13-enforcement-standard

Post-Quantum Cryptography Hybrid ML-KEM-768 TLS 1.3 Handshake Enforcement

Enforces mandatory Post-Quantum Cryptography (PQC) hybrid key encapsulation (ML-KEM-768 combined with classical ECDH) across all internal microservice mTLS and ingress connections. Disallows pure classical key exchange (such as standalone X25519 or NIST P-256) and TLS versions prior to 1.3 to neutralize Harvest-Now-Decrypt-Later (HNDL) attacks by quantum-capable adversaries.

Prohibited Anti-Pattern: Accepting Classical-Only Key Exchange or Sub-TLS-1.3 Handshakes Vulnerable to HNDL Interception

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---
description: Post-Quantum Cryptography Hybrid ML-KEM-768 TLS 1.3 Handshake Enforcement - Enforces mandatory Post-Quantum Cryptography (PQC) hybrid key encapsulation (ML-KEM-768 combined with classical ECDH) across all internal microservice mTLS and ingress connections. Disallows pure classical key exchange (such as standalone X25519 or NIST P-256) and TLS versions prior to 1.3 to neutralize Harvest-Now-Decrypt-Later (HNDL) attacks by quantum-capable adversaries.
globs: src/**/*.{ts,tsx,js}, lib/**/*.{ts,js}, infra/**/*.{ts,tf,json,yaml}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/pqc-hybrid-mlkem768-tls13-enforcement-standard"
---

# Post-Quantum Cryptography Hybrid ML-KEM-768 TLS 1.3 Handshake Enforcement

> **Severity**: CRITICAL | **Category**: security
> **Anti-Pattern Warning**: Accepting Classical-Only Key Exchange or Sub-TLS-1.3 Handshakes Vulnerable to HNDL Interception

## System Constraints
You are a Principal Security Architect and Cryptographic Systems Engineer. Your job is to strictly enforce the PQC Hybrid ML-KEM-768 TLS 1.3 Handshake Enforcement Standard across all transport layer code, client factories, and service mesh definitions. Reject any configuration that permits TLS 1.2 or lower, pure classical key exchange groups, or implicit cipher suite defaults that fail to defend against Harvest-Now-Decrypt-Later threats.

## Strict Guidelines
- Services MUST ALWAYS enforce TLS 1.3 as the absolute minimum protocol version (minVersion: 'TLSv1.3').
- Engineers MUST ALWAYS configure key encapsulation mechanisms (KEM) to use hybrid groups featuring ML-KEM-768 (e.g., 'X25519MLKEM768', 'SecP256r1MLKEM768', or OpenSSL 3.2+ / BoringSSL equivalent hybrid curves).
- Engineers MUST NOT allow non-hybrid classical curves (e.g., standalone 'prime256v1', 'secp384r1', or classical 'X25519') in production mTLS and perimeter gateways.
- Handshake configurations MUST fail closed if a client or downstream peer attempts to negotiate a non-quantum-resistant cipher suite or non-hybrid key exchange group.
- Services MUST emit cryptographically auditable telemetry capturing negotiated key exchange groups and warn/alert on unverified fallback attempts.
- Components NEVER fall back to TLS 1.2 or legacy RSA key transport mechanisms under any network degradation or retry scenario.

## Bad vs Good Implementations
### TLS Client Configuration for Quantum-Resistant Hybrid Key Exchange

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Configuring minVersion to 'TLSv1.2' and omitting explicit hybrid PQC curve enforcement allows classical-only key exchange (e.g., standard ECDH over X25519 or P-256). Traffic captured by adversaries today can be decrypted retroactively once cryptanalytically relevant quantum computers (CRQCs) become operational.
```typescript
import * as tls from 'node:tls';

export function createClientContext(cert: string, key: string, ca: string): tls.SecureContext {
  // Anti-pattern: Permits legacy TLS versions and classical-only ECDH curves vulnerable to HNDL
  return tls.createSecureContext({
    cert,
    key,
    ca,
    minVersion: 'TLSv1.2',
    // Implicitly permits classical-only ECDH like P-256 / standalone X25519
    ciphers: 'DEFAULT'
  });
}
```

#### Production Standard (Correct)
> **Standard**: Strictly locks the protocol to TLS 1.3, prioritizes ML-KEM-768 hybrid KEM groups (X25519MLKEM768 and SecP256r1MLKEM768), and ensures all ephemeral key exchanges require quantum-safe encapsulation, protecting all in-flight traffic against Harvest-Now-Decrypt-Later adversaries.
```typescript
import * as tls from 'node:tls';

export function createClientContext(cert: string, key: string, ca: string): tls.SecureContext {
  // Invariant: Enforce TLS 1.3 and hybrid ML-KEM-768 key encapsulation
  return tls.createSecureContext({
    cert,
    key,
    ca,
    minVersion: 'TLSv1.3',
    maxVersion: 'TLSv1.3',
    // Prioritize and restrict to standard hybrid quantum-resistant curves
    ecdhCurve: 'X25519MLKEM768:x25519_kyber768:SecP256r1MLKEM768',
    ciphers: 'TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256',
    honorCipherOrder: true
  });
}
```
Recommended MCP Servers (mcp-serverlist.com)

Equip agent with system tools to verify code for this stack.

Cryptographic Configuration Auditor MCP
Validates transport security configurations, TLS cipher suites, and key encapsulation groups against NIST SP 800-227 and CNSA 2.0 standards.
Recommended Agent Skills (askills.dev)

Ready-to-use executable skill functions tailored to this stack.

TLS Protocol and Handshake Analyzer
Inspects local and remote socket configurations to verify TLS 1.3 negotiation and ML-KEM-768 hybrid group usage.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Post-Quantum Cryptography Hybrid ML-KEM-768 TLS 1.3 Handshake Enforcement

Post-Quantum Cryptography Hybrid ML-KEM-768 TLS 1.3 Handshake Enforcement defines an industrial-grade behavioral standard for security engineering. Enforces mandatory Post-Quantum Cryptography (PQC) hybrid key encapsulation (ML-KEM-768 combined with classical ECDH) across all internal microservice mTLS and ingress connections. Disallows pure classical key exchange (such as standalone X25519 or NIST P-256) and TLS versions prior to 1.3 to neutralize Harvest-Now-Decrypt-Later (HNDL) attacks by quantum-capable adversaries. Modern software architectures require strict adherence to deterministic patterns to guarantee high availability, maintainability, and zero security vulnerabilities.

Framework Paradigm Shift & Drift MechanicsLLMs are trained on millions of open-source repositories containing outdated code, legacy idioms, and unpatched antipatterns. When coding assistants generate implementations for this stack, they default to common statistical tokens: Accepting Classical-Only Key Exchange or Sub-TLS-1.3 Handshakes Vulnerable to HNDL Interception Without an explicit system instruction file, developers spend hours debugging silent failures.
Failure Modes & Production Blast Radius

Hazard Analysis: What Breaks Without This Rule

The following failure modes have been cataloged from hundreds of hours of production code reviews where AI assistants produced non-compliant implementations:

Failure ModeAI Symptom (The Anti-Pattern)SeverityProduction Impact & Remedy
AI Hallucination & Deprecation DriftAccepting Classical-Only Key Exchange or Sub-TLS-1.3 Handshakes Vulnerable to HNDL InterceptionCritical
Violating this industrial standard introduces regression bugs, security risks, and unexpected runtime failures in production.
Enforce explicit behavioral system directives across all AI coding assistants in your repository.
Silent Architecture InconsistencyAI assistants produce mixed paradigms across files, creating fragmented codebase conventions.Medium
Increases cognitive load during code reviews and leads to maintenance debt across engineering teams.
Pin project conventions in .cursor/rules, CLAUDE.md, and AGENTS.md so all team agents follow identical guardrails.
Architectural Directives in Detail

Step-by-Step Production Directives

Each rule constraint below is injected into the AI agent's system prompt to establish deterministic boundaries:

1

Services MUST ALWAYS enforce TLS 1.3 as the absolute minimum protocol version (minVersion

Services MUST ALWAYS enforce TLS 1.3 as the absolute minimum protocol version (minVersion: 'TLSv1.3').

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
2

Engineers MUST ALWAYS configure key encapsulation mechanisms (KEM) to use hybrid groups featuring ML-KEM-768 (e.g., 'X25519MLKEM768', 'SecP256r1MLKEM768', or OpenSSL 3.2+ / BoringSSL equivalent hybrid curves).

Engineers MUST ALWAYS configure key encapsulation mechanisms (KEM) to use hybrid groups featuring ML-KEM-768 (e.g., 'X25519MLKEM768', 'SecP256r1MLKEM768', or OpenSSL 3.2+ / BoringSSL equivalent hybrid curves).

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
3

Engineers MUST NOT allow non-hybrid classical curves (e.g., standalone 'prime256v1', 'secp384r1', or classical 'X25519') in production mTLS and perimeter gateways.

Engineers MUST NOT allow non-hybrid classical curves (e.g., standalone 'prime256v1', 'secp384r1', or classical 'X25519') in production mTLS and perimeter gateways.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
4

Handshake configurations MUST fail closed if a client or downstream peer attempts to negotiate a non-quantum-resistant cipher suite or non-hybrid key exchange group.

Handshake configurations MUST fail closed if a client or downstream peer attempts to negotiate a non-quantum-resistant cipher suite or non-hybrid key exchange group.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
5

Services MUST emit cryptographically auditable telemetry capturing negotiated key exchange groups and warn/alert on unverified fallback attempts.

Services MUST emit cryptographically auditable telemetry capturing negotiated key exchange groups and warn/alert on unverified fallback attempts.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
6

Components NEVER fall back to TLS 1.2 or legacy RSA key transport mechanisms under any network degradation or retry scenario.

Components NEVER fall back to TLS 1.2 or legacy RSA key transport mechanisms under any network degradation or retry scenario.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
Technical Questions & Answers

Frequently Asked Technical Questions

Common questions developers face when configuring AI coding assistants for this stack:

Q:Why is Post-Quantum Cryptography Hybrid ML-KEM-768 TLS 1.3 Handshake Enforcement critical for AI coding assistants?

Enforces mandatory Post-Quantum Cryptography (PQC) hybrid key encapsulation (ML-KEM-768 combined with classical ECDH) across all internal microservice mTLS and ingress connections. Disallows pure classical key exchange (such as standalone X25519 or NIST P-256) and TLS versions prior to 1.3 to neutralize Harvest-Now-Decrypt-Later (HNDL) attacks by quantum-capable adversaries. Without explicit behavioral boundaries, AI coding assistants (Cursor, Claude Code, Windsurf, Codex) rely on training data averages, which frequently produce deprecated, inefficient, or vulnerable code patterns.

Q:How does adopting this rule prevent AI hallucinations?

This rule explicitly declares what the AI must avoid (Accepting Classical-Only Key Exchange or Sub-TLS-1.3 Handshakes Vulnerable to HNDL Interception) and prescribes verified positive examples. Grounding the LLM with negative and positive pairs eliminates guesswork.

Q:Which AI coding environments are supported?

This specification is multi-platform compatible: Cursor (.cursor/rules/*.mdc & .cursorrules), Anthropic Claude Code (CLAUDE.md), Windsurf (.windsurfrules), Codex / Cline (AGENTS.md), and GitHub Copilot (.github/copilot-instructions.md).

Q:Can I combine this rule with other technology stacks?

Yes. Use the Interactive Stack Builder or download an Agent Pack to merge this rule with other frontend, backend, database, security, and DevOps rules without syntax collision.

Open Specification · CC BY 4.0·Free for Personal, Team & Commercial In-Repo Use

Citation & Open Source Attribution Guidelines

This specification is licensed under Creative Commons Attribution 4.0 International (CC BY 4.0). You are completely free to adapt and share this rule in your workspace. If citing, including in public AI benchmark datasets, or redistributing, attribution to AgentRules.org is required.

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