Trace

Quantum computers use qubits that can exist in superposition, allowing them to process multiple states simultaneously. This exponentially increases computational power for certain problems.

Current encryption (RSA, ECC) relies on the difficulty of factoring large numbers or solving discrete logarithms. Classical computers would need billions of years to break 2048-bit RSA.

Shor's algorithm on a sufficiently powerful quantum computer could break RSA in hours. But wait - I should revise my estimate of 'sufficiently powerful'...

Revision: Breaking 2048-bit RSA requires ~4,000 logical qubits. Current quantum computers have ~1,000 physical qubits with high error rates. We need error correction, requiring millions of physical qubits. Timeline: 10-15 years, not imminent.

This creates a "harvest now, decrypt later" threat. Adversaries may be storing encrypted data today to decrypt once quantum computers mature. Sensitive data with 15+ year relevance is already at risk.

Branch A - Defense: Post-quantum cryptography (NIST standards like CRYSTALS-Kyber) uses lattice problems that are hard for both classical and quantum computers. Migration should start now.

Branch B - Offense: Quantum key distribution (QKD) uses quantum mechanics itself for provably secure key exchange. Laws of physics prevent eavesdropping without detection.

Synthesis: Organizations should (1) inventory cryptographic assets, (2) prioritize long-lived sensitive data, (3) begin hybrid classical/post-quantum implementations, (4) monitor NIST standards. The threat is real but manageable with proactive migration.