The Silent Quantum Threat Happening Right Now
Harvest now, decrypt later (HNDL) is not a future threat — it is happening today. Nation-state adversaries and sophisticated attackers are recording encrypted data from the internet, including blockchain transactions, with the intention of decrypting it when quantum computers become powerful enough. The NSA warned about this strategy in 2015.
Why Blockchain Is the Perfect HNDL Target
Most HNDL attacks require the attacker to intercept and store encrypted traffic — an expensive, targeted operation. Blockchain is different. Every transaction is publicly broadcast and permanently stored by design. An attacker does not need to intercept anything — they just download the blockchain. Every Bitcoin and Ethereum transaction ever made, with every exposed public key, is already harvested.
What Happens When Quantum Arrives
When quantum computers reach approximately 4,000 logical qubits, an attacker with harvested blockchain data can:
- Run Shor's algorithm on every exposed public key
- Derive the corresponding private keys
- Sign transactions draining every affected wallet
- Execute this across millions of wallets simultaneously
For Bitcoin, approximately 25% of all BTC (early P2PK addresses) has permanently exposed public keys. For Ethereum, every address that has ever sent a transaction is exposed.
The Timeline Mismatch
Here is the critical issue: by the time quantum computers can decrypt, it is too late to protect historical data. You cannot un-expose a public key that has been on the blockchain for 10 years. The only defense against HNDL is to use quantum-resistant encryption before your data is harvested.
BMIC's Pre-emptive Defense
BMIC uses CRYSTALS-Kyber encryption from day one. Harvested BMIC transaction data is useless to future quantum attackers because Kyber's lattice-based security is resistant to Shor's algorithm. The HNDL strategy fails completely against NIST-standard post-quantum cryptography.