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securitycritical PriorityID: pqc-mlkem-kyber-tls13-mandate

Post-Quantum Cryptography (ML-KEM/Kyber) TLS 1.3 Mandate

Enforces post-quantum hybrid key exchange (ML-KEM/Kyber with classical elliptic curves) on all TLS 1.3 ingress and egress communication channels. Defends against 'Harvest Now, Decrypt Later' (HNDL) adversarial operations targeting enterprise APIs and data-in-transit boundaries. Disallows legacy TLS protocols (< 1.3) and classical-only key agreement configurations across all perimeter endpoints.

Prohibited Anti-Pattern: Using classical-only key exchanges (ECDHE/RSA) or permitting TLS versions below 1.3 on public-facing gateways.

Export Ready-to-Drop Configuration

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---
description: Post-Quantum Cryptography (ML-KEM/Kyber) TLS 1.3 Mandate - Enforces post-quantum hybrid key exchange (ML-KEM/Kyber with classical elliptic curves) on all TLS 1.3 ingress and egress communication channels. Defends against 'Harvest Now, Decrypt Later' (HNDL) adversarial operations targeting enterprise APIs and data-in-transit boundaries. Disallows legacy TLS protocols (< 1.3) and classical-only key agreement configurations across all perimeter endpoints.
globs: src/**/*.{ts,js}, infrastructure/**/*.{ts,yaml,json}, server/**/*.{ts,go,rs}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/pqc-mlkem-kyber-tls13-mandate"
---

# Post-Quantum Cryptography (ML-KEM/Kyber) TLS 1.3 Mandate

> **Severity**: CRITICAL | **Category**: security
> **Anti-Pattern Warning**: Using classical-only key exchanges (ECDHE/RSA) or permitting TLS versions below 1.3 on public-facing gateways.

## System Constraints
You are a Principal Security Architect enforcing Post-Quantum Cryptography (PQC) standards across enterprise networks. Mandate TLS 1.3 as the strict minimum protocol version and ensure all key encapsulation mechanisms (KEM) utilize NIST-standardized hybrid ML-KEM (Kyber-768 hybrid with X25519 or SecP256r1). Reject any configuration permitting classical-only key exchange or TLS downgrades.

## Strict Guidelines
- Services MUST enforce 'TLSv1.3' as both 'minVersion' and 'maxVersion' for all public-facing perimeter gateways and zero-trust east-west interconnects.
- Engineers MUST configure hybrid post-quantum key agreement groups (e.g., 'X25519MLKEM768', 'x25519_kyber768', or 'SecP256r1MLKEM768') in secure TLS context definitions.
- Engineers MUST NOT permit fallback to RSA key exchange or pure classical Diffie-Hellman (DH/ECDH) curves on external API entry points.
- Clients (e.g., Axios, Fetch, Undici, Node HTTPS Agent) MUST specify post-quantum group negotiation when initiating requests to external microservices.
- Cryptographic libraries MUST utilize engines backed by OpenSSL 3.2+ with liboqs, AWS-LC, or BoringSSL compiled with ML-KEM support.

## Bad vs Good Implementations
### Node.js HTTPS/TLS Server Configuration with Hybrid ML-KEM

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Configuring TLSv1.2 with classical-only ECDHE curves exposes all transit data to retrospective decryption once cryptanalytically relevant quantum computers (CRQCs) become viable.
```typescript
import https from 'node:https';
import fs from 'node:fs';

// VULNERABLE: Classical-only TLS configuration vulnerable to Harvest-Now-Decrypt-Later
const insecureServer = https.createServer({
  key: fs.readFileSync('/etc/ssl/privkey.pem'),
  cert: fs.readFileSync('/etc/ssl/fullchain.pem'),
  // Permits legacy TLS and defaults to classical curves (P-256 / X25519 only)
  minVersion: 'TLSv1.2',
  ciphers: 'ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256',
  honorCipherOrder: true
}, (req, res) => {
  res.writeHead(200);
  res.end('Operational');
});

insecureServer.listen(8443);
```

#### Production Standard (Correct)
> **Standard**: Mandates TLS 1.3 and specifies 'X25519MLKEM768' and 'x25519_kyber768' as the prioritized key-agreement groups, rendering harvested traffic immune to future quantum cryptanalysis.
```typescript
import tls from 'node:tls';
import https from 'node:https';
import fs from 'node:fs';

// SECURE: Enforced TLS 1.3 with Hybrid ML-KEM (Kyber768 + X25519)
const pqcSecureContextOptions: tls.SecureContextOptions = {
  key: fs.readFileSync('/etc/ssl/privkey.pem'),
  cert: fs.readFileSync('/etc/ssl/fullchain.pem'),
  // Strictly mandate TLS 1.3; TLS 1.2 and below are explicitly rejected
  minVersion: 'TLSv1.3',
  maxVersion: 'TLSv1.3',
  // Require ML-KEM hybrid curves as primary key negotiation mechanisms
  ecdhCurve: 'X25519MLKEM768:x25519_kyber768:X25519:P-256',
  // Modern TLS 1.3 AEAD ciphersuites
  ciphers: 'TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256'
};

const pqcServer = https.createServer(pqcSecureContextOptions, (req, res) => {
  res.setHeader('Strict-Transport-Security', 'max-age=63072000; includeSubDomains; preload');
  res.writeHead(200, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify({ status: 'secured_via_hybrid_ml_kem' }));
});

pqcServer.listen(8443);
```
Recommended MCP Servers (mcp-serverlist.com)

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

TLS/SSL Configuration Auditor MCP
Inspects and audits runtime TLS contexts and network endpoints for quantum-resistant cipher suites and curve negotiation.
Recommended Agent Skills (askills.dev)

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

testssl.sh Protocol Checker
Validates server cipher suites, curve support (ML-KEM/Kyber), and TLS 1.3 strict enforcement from the command line.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Post-Quantum Cryptography (ML-KEM/Kyber) TLS 1.3 Mandate

Post-Quantum Cryptography (ML-KEM/Kyber) TLS 1.3 Mandate defines an industrial-grade behavioral standard for security engineering. Enforces post-quantum hybrid key exchange (ML-KEM/Kyber with classical elliptic curves) on all TLS 1.3 ingress and egress communication channels. Defends against 'Harvest Now, Decrypt Later' (HNDL) adversarial operations targeting enterprise APIs and data-in-transit boundaries. Disallows legacy TLS protocols (< 1.3) and classical-only key agreement configurations across all perimeter endpoints. 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: Using classical-only key exchanges (ECDHE/RSA) or permitting TLS versions below 1.3 on public-facing gateways. 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 DriftUsing classical-only key exchanges (ECDHE/RSA) or permitting TLS versions below 1.3 on public-facing gateways.Critical
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 enforce 'TLSv1.3' as both 'minVersion' and 'maxVersion' for all public-facing perimeter gateways and zero-trust east-west interconnects.

Services MUST enforce 'TLSv1.3' as both 'minVersion' and 'maxVersion' for all public-facing perimeter gateways and zero-trust east-west interconnects.

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 configure hybrid post-quantum key agreement groups (e.g., 'X25519MLKEM768', 'x25519_kyber768', or 'SecP256r1MLKEM768') in secure TLS context definitions.

Engineers MUST configure hybrid post-quantum key agreement groups (e.g., 'X25519MLKEM768', 'x25519_kyber768', or 'SecP256r1MLKEM768') in secure TLS context definitions.

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 permit fallback to RSA key exchange or pure classical Diffie-Hellman (DH/ECDH) curves on external API entry points.

Engineers MUST NOT permit fallback to RSA key exchange or pure classical Diffie-Hellman (DH/ECDH) curves on external API entry points.

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

Clients (e.g., Axios, Fetch, Undici, Node HTTPS Agent) MUST specify post-quantum group negotiation when initiating requests to external microservices.

Clients (e.g., Axios, Fetch, Undici, Node HTTPS Agent) MUST specify post-quantum group negotiation when initiating requests to external microservices.

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

Cryptographic libraries MUST utilize engines backed by OpenSSL 3.2+ with liboqs, AWS-LC, or BoringSSL compiled with ML-KEM support.

Cryptographic libraries MUST utilize engines backed by OpenSSL 3.2+ with liboqs, AWS-LC, or BoringSSL compiled with ML-KEM support.

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 (ML-KEM/Kyber) TLS 1.3 Mandate critical for AI coding assistants?

Enforces post-quantum hybrid key exchange (ML-KEM/Kyber with classical elliptic curves) on all TLS 1.3 ingress and egress communication channels. Defends against 'Harvest Now, Decrypt Later' (HNDL) adversarial operations targeting enterprise APIs and data-in-transit boundaries. Disallows legacy TLS protocols (< 1.3) and classical-only key agreement configurations across all perimeter endpoints. 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 (Using classical-only key exchanges (ECDHE/RSA) or permitting TLS versions below 1.3 on public-facing gateways.) 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.

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