SOURCE_URL: https://majikah.solutions/products/majik-message/docs/wiki-hndl --- title: "Harvest Now, Decrypt Later" id: "wiki-hndl" group: "majik-message" type: "products" version: "1.1.0" lastUpdated: "2026-02-19T00:00:00.000Z" difficulty: "Beginner" time: "4-5 minutes" tags: [hndl, harvest-now-decrypt-later, quantum, threat-model, post-quantum, nation-state, shor-algorithm, ecdh, security] --- # Harvest Now, Decrypt Later > The attack strategy that makes post-quantum encryption urgent today — why messages encrypted right now could be decrypted by quantum computers in the future ## Overview Harvest Now, Decrypt Later (HNDL) is the reason post-quantum encryption matters right now, not just in the future. Nation-state actors are already collecting encrypted internet traffic with the intention of decrypting it once quantum computers become powerful enough to break today's encryption. If you're using classical encryption today, any sensitive information you transmit is potentially at risk — not from today's computers, but from tomorrow's quantum ones. ### What is Harvest Now, Decrypt Later? HNDL is a surveillance strategy where an adversary captures and stores encrypted internet traffic today, even though they cannot decrypt it yet. The bet is that quantum computers — which will be powerful enough to break classical encryption — will exist within the next decade. At that point, the adversary retrieves the stored ciphertext and decrypts years or decades worth of previously 'secure' communications. The attack is passive and undetectable: the victim has no way of knowing their encrypted traffic was recorded. And there is no defense available after the fact — once the traffic is captured, it cannot be un-captured. ### Why Classical Encryption Is Vulnerable Almost all widely-used secure messaging platforms — Signal, WhatsApp, iMessage, Telegram, and most enterprise messaging tools — use Elliptic Curve Diffie-Hellman (ECDH) for key exchange. ECDH's security relies on the mathematical difficulty of the discrete logarithm problem. In 1994, mathematician Peter Shor published an algorithm — now called Shor's Algorithm — that a sufficiently powerful quantum computer could run to solve the discrete logarithm problem efficiently. This would completely break ECDH key exchange, exposing all messages ever encrypted with those keys. Every message sent on these platforms today is potentially vulnerable to an HNDL attack. ### When Is the Quantum Threat Real? Estimates from security researchers and national intelligence agencies place the arrival of 'cryptographically relevant quantum computers' — ones powerful enough to run Shor's Algorithm against production ECDH keys — somewhere between 2030 and 2040. The exact timeline is uncertain, but national security agencies including CISA, NSA, and NIST have all issued guidance recommending that organizations begin migrating to post-quantum cryptography immediately, precisely because of HNDL. Data that must remain confidential beyond the next 5–10 years — legal records, health information, national security communications, financial data, journalist sources — should be protected with post-quantum encryption today. ### How Majik Message Addresses HNDL Majik Message uses ML-KEM-768 (FIPS-203) — a NIST-standardized lattice-based key encapsulation mechanism — for all message encryption. Lattice-based cryptography is not vulnerable to Shor's Algorithm. A quantum computer running Shor's Algorithm against an ML-KEM-768 ciphertext gains no advantage over a classical computer. This means traffic captured today and stored for future quantum decryption remains secure — the math does not break. Additionally, Majik Message's hybrid approach combines ML-KEM-768 with X25519, so messages are secure against both classical attackers today and quantum attackers in the future. > **NOTE:** Who Should Care About HNDL? Anyone whose communications need to remain confidential for more than a few years: legal professionals (attorney-client privilege), healthcare providers (patient records), journalists (protecting sources), government and defense contractors (classified adjacent communications), financial institutions (transaction and strategy data), and researchers working on sensitive or competitive projects. If the information you're sending today would still be damaging if exposed in 2035, it should be protected with post-quantum encryption today. ### What Majik Message Does Not Protect Against Post-quantum encryption addresses one specific threat: the mathematical breaking of key exchange algorithms by quantum computers. It does not protect against: device compromise — if an attacker has access to your unlocked device with private keys in memory, they can decrypt messages regardless of the encryption algorithm; traffic analysis — message timing, frequency, and participant relationships are visible to the relay and network observers; endpoint malware — keyloggers, screen capture, or other software on your device are outside the cryptographic threat model; IP address exposure — the relay sees your IP address; use Tor or a VPN if IP anonymity is required. Majik Message is a layer of a complete security posture, not a complete solution on its own.