Simply put
- BIP 360 co-authors identify Bitcoin signatures as a primary quantum threat for blockchain.
- About 30% of Bitcoins are kept with public keys visible.
- As quantum technology advances, both Bitcoin and Ethereum developers are boosting their quantum strategies.
At the recent Ethereum developer conference, ETH Denver, discussions centered on developing in a declining market and leveraging blockchain for AI agents. One panel examined the potential survival of Bitcoin’s cryptocurrency in a future influenced by quantum computing.
The talk about Bitcoin’s resilience against quantum threats gained focus, specifically regarding what elements could fail first. Hunter Beast, a co-author of BIP 360—which addresses blockchain’s quantum challenges—mentioned that confusion often arises from Bitcoin’s hashing algorithm.
“Hashing algorithms like SHA-256 are considered nearly impossible to crack, even with the largest theoretical quantum computers,” Beast noted. “We speculate that breaking a 256-bit hash using Grover’s algorithm would necessitate a quantum computer larger than the moon.”
Grover’s algorithm, developed by computer scientists in 1996, notably speeds up brute-force searches and consequently diminishes the security of hash functions like Bitcoin’s SHA-256.
“That’s not our main concern for the next five years,” Beast stated. “What we’ll need to worry about is signing, which affects the shawl too.”
Originating from mathematicians in 1994, Scholl’s algorithm provides the math for public key cryptography. Bitcoin relies on elliptic curve cryptography for digital signatures, and if a sufficiently powerful quantum computer emerges, Scholl’s algorithm could extract the private key from the public key.
Alex Pruden, CEO of blockchain security firm Project Eleven, elaborated on the significance of this issue.
“Bitcoin ownership hinges entirely on digital signature capabilities,” Pruden explained during the discussion. “If someone knows your public key—something meant to be safe to share—they could reconstruct your private key. So, just having access to your public key would mean they essentially own your Bitcoin.”
Current machines can’t accomplish this. However, Pruden highlighted recent strides in quantum computing by major players like Google and IBM, suggesting that swift advancements may be on the horizon.
“In December 2024, Google unveiled Willow, a quantum computer showcasing subthreshold error correction,” Pruden shared. “Prior to that, the scalability of quantum computing was uncertain, but Google proved it certainly is.”
This dialogue is happening concurrently with the crypto industry’s preparations for the eventuality of operational quantum computers.
The Ethereum Foundation has recently created a post-quantum security team, and Coinbase assembled an advisory board to explore quantum threats to Bitcoin and other digital currencies. While researchers discuss the urgency of the threat, Coinbase’s CEO Brian Armstrong believes the issue is addressable.
Projections about the hardware needed to compromise Bitcoin’s signature system have evolved. In 2021, estimates suggested that around 20 million qubits would be necessary to breach Bitcoin’s security. Recently, researchers from Iceberg Quantum proposed that this figure might be slashed to about 100,000 qubits.
Project Eleven emphasizes that exposure is already a reality. The “Bitcoin Risk List” outlines that over 6.9 million coins reside in addresses where public keys are exposed, including 1.7 million coins from Bitcoin’s early mining days.
“Essentially, a third of the total Bitcoin supply is at risk from long exposure attacks,” Beast remarked.
Isabel Foxen Duke, another co-author on BIP 360, pointed out that the dilemma isn’t just a technical one.
“Bitcoin and its quantum-adapted counterparts face numerous challenges that extend beyond just post-quantum cryptography,” she commented.
Some older coins, as Foxen Duke noted, might never transition to quantum-secure addresses, including those believed to belong to Bitcoin’s creator, Satoshi Nakamoto.
“There are proposals to completely freeze payment addresses for Satoshi’s coins and all public keys,” she said. “These are contentious and complex questions, as achieving consensus on such matters poses a significant political challenge.”
However, she cautioned that if quantum capabilities were realized before a consensus was reached on transitioning, it could lead to disastrous outcomes for the Bitcoin network.
“If a quantum computer emerges and within hours, 4 million Bitcoins flood the market, and someone exploits that, it could threaten the existence of the Bitcoin project, regardless of post-quantum cryptography,” Foxen Duke stated.
