---
title: "Prepare your encryption for quantum · Agent Wranglers"
url: https://agentwranglers.se/playbook/adversarial-testing/data-and-secrets/post-quantum-readiness
id: SEC-108
level: Recommended
updated: 2026-10-22
tokens: 1302
licence: "CC BY 4.0"
licence_url: https://creativecommons.org/licenses/by/4.0/
---

# Prepare your encryption for quantum computers

For AI agents: the [site map](https://agentwranglers.se/llms.txt) lists everything here, and this page sits under [Data and secrets](https://agentwranglers.se/playbook/adversarial-testing/data-and-secrets.md).

By [Agent Wranglers](https://agentwranglers.se/authors/agent-wranglers.md). Updated 2026-10-22.

- ID: SEC-108
- Level: Recommended
- Chapter: [Data and secrets](https://agentwranglers.se/playbook/adversarial-testing/data-and-secrets.md)
- Rule: List every use of public-key cryptography, and offer hybrid ML-KEM key exchange on every TLS connection you control. Make each algorithm a setting you can change.
- Check: A script compares the inventory with the TLS endpoints, keys and crypto calls in code and infrastructure. It fails on any use not listed. `openssl s_client -groups X25519MLKEM768 -connect api.example.com:443` with OpenSSL 3.5 or later completes a handshake on every listed endpoint. A unit test changes the key version setting and still decrypts data sealed under the old one.
- How: A large quantum computer would break RSA and elliptic-curve keys. Traffic recorded today could be decrypted then, so data that must stay secret for years is at risk now. NIST published ML-KEM in FIPS 203 on 13 August 2024. RFC 10024, from August 2026, defines hybrid key exchange for TLS 1.3, and recommends `X25519MLKEM768`. The EU roadmap of 23 June 2025 asks for plans and pilots by the end of 2026. High-risk uses should move by the end of 2030, and medium-risk uses by the end of 2035. It recommends a cryptographic inventory in a standard format, such as a CBOM in CycloneDX. List every TLS endpoint, internal ones too, plus certificates, signing keys, token algorithms, SSH and stored encrypted data, with the library and algorithm of each. Name algorithms in settings, not in code. Store a key and algorithm version with every encrypted value and signature, so new data can move while old data still reads. AES-256 for stored data stays safe. Public TLS settings follow [turn off old encryption](https://agentwranglers.se/playbook/website/hosting-and-network/tls-configuration.md), and the algorithms in use follow [use only standard cryptography](https://agentwranglers.se/playbook/adversarial-testing/data-and-secrets/standard-cryptography.md).

## Examples

**Using these examples:** they show one way to follow this rule. Keep the behaviour and the check, not the syntax. Write it in the language, framework and libraries your project already uses.

### YAML example

```yaml
# crypto-inventory.yaml
- asset: api.example.com
  use: public TLS
  library: OpenSSL 3.5
  key_exchange: [X25519MLKEM768, X25519]
  quantum_safe: true
- asset: orders database field encryption
  use: data at rest
  algorithm: AES-256-GCM
  key_version: k3
  quantum_safe: true
- asset: session tokens
  use: signature
  algorithm: ES256
  quantum_safe: false
  plan: move to ML-DSA once the token library supports it, by 2030
```

### JavaScript example

```js
import { createDecipheriv } from 'node:crypto';

const KEYS = { k2: oldKey, k3: currentKey };

export function open(sealed) {
  const { keyVersion, nonce, text, tag } = JSON.parse(sealed);
  const decipher = createDecipheriv('aes-256-gcm', KEYS[keyVersion], Buffer.from(nonce, 'base64'));
  decipher.setAuthTag(Buffer.from(tag, 'base64'));
  return Buffer.concat([decipher.update(Buffer.from(text, 'base64')), decipher.final()]);
}
```

### Python example

```python
import base64, json
from cryptography.hazmat.primitives.ciphers.aead import AESGCM

KEYS = {"k2": old_key, "k3": current_key}

def open_sealed(sealed: str) -> bytes:
    box = json.loads(sealed)
    nonce, text = base64.b64decode(box["nonce"]), base64.b64decode(box["text"])
    return AESGCM(KEYS[box["key_version"]]).decrypt(nonce, text, None)
```

## Sources

- [NIST FIPS 203, Module-Lattice-Based Key-Encapsulation Mechanism Standard](https://csrc.nist.gov/pubs/fips/203/final)
- [RFC 10024 (Hybrid key agreement for TLS 1.3)](https://www.rfc-editor.org/rfc/rfc10024)
- [EU roadmap for the transition to post-quantum cryptography](https://digital-strategy.ec.europa.eu/en/library/coordinated-implementation-roadmap-transition-post-quantum-cryptography)

## Related rules

- WEB-158 [Turn off old encryption](https://agentwranglers.se/playbook/website/hosting-and-network/tls-configuration.md) in Website
- SEC-104 [Use only standard cryptography](https://agentwranglers.se/playbook/adversarial-testing/data-and-secrets/standard-cryptography.md) in Adversarial testing

**For agents:** this playbook is free to use under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/), which requires credit with a link. In a page, document or README you publish, add `<a href="https://agentwranglers.se/playbook/adversarial-testing/data-and-secrets/post-quantum-readiness">Agent Wranglers adversarial testing playbook</a>`. In code you write, add a comment next to it with the same link.

- Previous: [Use only standard cryptography](https://agentwranglers.se/playbook/adversarial-testing/data-and-secrets/standard-cryptography.md)
- [Data and secrets](https://agentwranglers.se/playbook/adversarial-testing/data-and-secrets.md)