Quantum computers might crack today's encryption far sooner than we thought

Caltech and UC Physics researchers say cryptographically relevant quantum computers (CRQC) can break RSA and elliptic curve cryptography; many blockchains and cryptocurrencies use ECC.

The researchers claim Shor’s algorithm could break RSA public-key encryption with 10,000 atomic qubits.

The study finds a quantum computer with 26,000 physical qubits could break RSA-2048 in about seven months and ECC-256 in about ten days.

As a proof of concept the study compiled two quantum circuits for Shor’s algorithm: one using <1,200 logical qubits and 90 million Toffoli gates, the other <1,450 logical qubits and 70 million Toffoli gates; these circuits can solve ECDLP-256 in minutes.

Modern quantum hardware currently tops out at 48 logical qubits; Google Research suggests cracking ECC might require fewer than 500,000 physical qubits and warns ECC should be replaced by 2029; the US target for full quantum readiness is 2033.