Quantum Breakthrough Factors 22-bit RSA Key, Bitcoin Faces Long-term Risk

Researchers at Shanghai University have made a significant breakthrough in quantum computing, successfully factoring a 22-bit RSA encryption key using a quantum annealing processor. This achievement, while modest in scale, marks a step forward in applying quantum technology to cryptography. The experiment utilized a D-Wave Systems quantum annealing processor with over 5,000 physical qubits, converting the factoring problem into a combinatorial optimization challenge.

The broken 22-bit key is considerably smaller than the 2,048-bit keys commonly used in modern encryption systems, which means that current RSA-based systems are not immediately threatened. However, the experiment highlights the potential for future advancements in quantum computing to pose a significant challenge to existing encryption methods. The computational difficulty of factoring large numbers into prime numbers scales exponentially with key size, suggesting that as quantum technology advances, it could eventually threaten current encryption standards.

Bitcoin, which uses different algorithms (ECDSA/SHA-256) than RSA, does not face an immediate threat from this specific quantum advance. Bitcoin secures transactions and private keys using the Elliptic Curve Digital Signature Algorithm (ECDSA) and the SHA-256 hash function, which rely on different mathematical problems than RSA. However, the relevance for Bitcoin is indirect, as the underlying mathematical assumptions face a potential long-term challenge.

Views on the timeline for a practical quantum threat vary. Adam Back, a Bitcoin developer and Blockstream founder, suggests that practical danger might be “one or two decades away.” Other experts monitoring quantum progress warn that the risk could materialize faster than expected. A late May report from Google Quantum AI heightened broader concerns, indicating that future quantum attacks could threaten not only RSA but also Elliptic Curve Diffie-Hellman (ECDH) encryption. ECDH shares mathematical foundations with Bitcoin’s ECDSA, both depending on the difficulty of solving the elliptic curve discrete logarithm problem.

Google’s analysis suggests that breaking a 2,048-bit RSA key might now require fewer than one million physical qubits, down from the previous estimate of 20 million. This reduction is attributed to better algorithms and improved error correction techniques. Logical qubits, formed from many error-corrected physical qubits, are the functional units for such complex tasks. This progress underscores a known risk: “harvest now, decrypt later” attacks, where adversaries could collect encrypted data today, hoping to decrypt it when sufficiently powerful quantum computers exist.

While Bitcoin’s specific algorithms aren’t broken, the underlying mathematical assumptions face a potential long-term challenge. The Shanghai experiment and Google’s analysis serve as reminders that crypto defenses must continue evolving to stay ahead of advancements in quantum computing. The post appeared first on ETHNews.