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What HNDL is, why it matters today even before quantum computers exist, and how QorTrace measures your exposure.

The one-paragraph version

HNDL is the threat model where an adversary records encrypted data today to decrypt it once a sufficiently large quantum computer arrives — possibly 5–10 years from now. The data being recorded today is forever-recorded; everything you encrypt with classical asymmetric crypto in 2026 is HNDL-vulnerable in perpetuity.

Why it matters before quantum exists

  1. Public keys broadcast on-chain are forever recorded. Every Bitcoin transaction reveals the spender's pubkey. Every Ethereum tx reveals an EOA. Once broadcast, an attacker with a future quantum computer can derive the private key via Shor's algorithm.
  2. TLS session secrets that get logged are forever recorded. Anyone with passive access to a fiber tap can record encrypted TLS traffic now, store it cheaply, and decrypt years later.
  3. Long-lived secrets are the most exposed. A bank's vault key that protects records for 30 years is at risk against a quantum computer 20 years from now. A session cookie that expires in an hour isn't.

What's safe and what isn't

  • Safe enough: AES-256, ChaCha20, SHA-256/3. Symmetric ciphers lose at most a quadratic factor against Grover — AES-256 stays at 128-bit security post-quantum.
  • HNDL-vulnerable: RSA, ECDSA, EdDSA, ECDH, classical Diffie- Hellman. Breakable by Shor on a quantum computer with ~4,000 logical qubits (today's machines have ~100).
  • PQC-safe: ML-KEM (Kyber), ML-DSA (Dilithium), SLH-DSA (SPHINCS+). These are the NIST FIPS 203/204/205 standards.

QorTrace's HNDL exposure score

For each address we scan, we measure:

  • Whether the pubkey is broadcast (the HNDL surface).
  • The dollar-at-risk on that address.
  • The age of exposure.

Combined into the 0–100 QorTrace Score (formula at /docs/methodology/how-the-score-is-computed).

What to do today

  1. Inventory. You can't migrate what you can't find. Atlas does this for wallets; Scanner does it ad-hoc.
  2. Sweep critical-tier addresses. Move funds to fresh, quasi-resistant addresses. Never reuse exposed addresses.
  3. Plan PQC adoption. Federal CNSA 2.0 mandates new systems be PQC-ready by 2030. Most enterprises target 2027–2028 for full migration to give a 2-year buffer.
  4. Audit critical contracts. QorTrace Standard ($4,900) catches the obvious crypto-primitive issues; Deep Dive scopes adversary modeling.

How urgent is "today"?

If your data needs to stay confidential for N years, and a cryptanalysis-relevant quantum computer arrives in Q years, then you need PQC live N years before Q. For a bank with 30-year record retention and Q ~ 2035, that's right now.