Harvest Now, Decrypt Later
Explore the looming threat of Harvest Now, Decrypt Later attacks in the quantum computing era. Learn how encrypted data collected today could be vulnerable tomorrow, and why post-quantum cryptography readiness is essential for cybersecurity.
A growing cybersecurity concern is the “Harvest Now, Decrypt Later” attack model. In this strategy, adversaries capture encrypted data today and simply store it—waiting for a future in which quantum computers can break today’s encryption. The danger isn’t hypothetical. It impacts any data that must remain confidential for years or decades.
Why This Matters Now
Even though large-scale quantum computers capable of breaking RSA and ECC don’t yet exist, research progress and government reports show that they are coming. Once available, attackers could:
- Decrypt previously captured TLS traffic
- Read private messages and emails from years prior
- Access financial and healthcare records
- Reveal proprietary research and internal communications
This means the vulnerability exists today, even if the decryption happens later.
How “Harvest Now, Decrypt Later” Works
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Intercept and capture encrypted data Examples: VPN traffic, TLS sessions, email archives, messaging backups.
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Store the ciphertext indefinitely Storage is cheap. Attackers can hold data for decades.
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Wait for quantum decryption capability Once quantum computers can break RSA/ECC, stored data becomes readable.
The attack succeeds without breaking encryption today—only patience is required.
Who Is Performing These Attacks?
Threat intelligence reports and national cybersecurity advisories suggest participation from:
- Nation-state intelligence agencies
- Organized cybercriminal groups
- Strategic corporate espionage actors
- Long-game persistent threat operators
They focus on data with long-term strategic value, not just passwords and credit cards.
The Path Forward: Post-Quantum Cryptography (PQC)
To defend against this threat, organizations are transitioning to post-quantum cryptographic algorithms, designed to resist both classical and quantum attacks.
The most practical first step is adopting hybrid TLS key exchange, which combines:
- A classical algorithm (e.g., X25519 or P-256)
- A quantum-resistant KEM (e.g., ML-KEM)
This ensures security even if one algorithm is eventually broken.
How to Assess Your Environment Today
Quick PQC Endpoint Readiness Test
Use QCready to instantly test whether your public-facing services support hybrid key exchange:
Fast, browser-based, and free for most use cases.
Full TLS Infrastructure Inventory
For large or complex environments, SSLboard provides:
- Cipher suite inventory
- TLS version and endpoint security scoring
- Detection of weak, legacy, or non-upgradeable systems
Key Takeaway
The quantum threat is not about what can be decrypted today—it’s about what can be decrypted later. Any data captured now may be readable in the future.
Transitioning to post-quantum security must begin before quantum computers reach practical cryptanalytic capability, not after.
Security today must account for the world 10+ years from now.