Image Credentials: Image Title: Quantum Computers Need Fewer Qubits to Crack Crypto Than Thought, Google Warns Source: (sora.openai) Date: March 2025. Attribution: This image was created using AI-generated imagery (sora.openai) and does not depict a real-world scene.
By Open Chronicle Staff with Agencies
MOUNTAIN VIEW, Calif. — Google researchers have dramatically accelerated the timeline for “Q-Day”—the hypothetical moment quantum computers become powerful enough to break modern digital security, revealing that the resources required to compromise major cryptocurrencies like Bitcoin and Ethereum are far lower than previously estimated.
In a research paper released Monday, Google’s Quantum AI team demonstrated a “20-fold reduction” in the number of physical qubits needed to crack the 256-bit elliptic curve cryptography (ECDLP-256) that currently secures the vast majority of blockchain private keys.
The Nine-Minute Window
The study suggests that a strategically optimized quantum computer could derive a Bitcoin private key from a public key in as little as nine minutes. This timeframe is critical because it fits within Bitcoin’s average 10-minute block time, enabling a theoretical “on-spend attack.”
In such an attack, a quantum adversary would intercept a public key the moment a user broadcasts a transaction. By cracking the private key in under ten minutes, the attacker could forge a competing transaction to divert the funds to their own wallet before the original transaction is confirmed by the network.
“My confidence in Q-Day by 2032 has shot up significantly,” said Justin Drake, an Ethereum researcher and co-author of the study. Drake estimated a 10% chance that quantum computers will be capable of recovering private keys from exposed public keys by that date.
Ethereum’s “At-Rest” Vulnerability
While Bitcoin faces a race against the clock, the researchers warned that Ethereum’s architecture makes it susceptible to “at-rest attacks,” which do not require a specific timing window.
Because the Ethereum account model permanently exposes a public key on the blockchain, the moment a user sends their first transaction, a quantum attacker could take days or even weeks to derive the private key at their leisure. Google estimated that a quantum computer could crack the 1,000 wealthiest exposed Ethereum accounts, collectively holding approximately 20.5 million ETH, in fewer than nine days.
“This results in account vulnerability: a systemic, unavoidable exposure that cannot be mitigated by user behavior,” the report stated, noting that only a protocol-wide transition to Post-Quantum Cryptography (PQC) can solve the issue.
Accelerating the Migration
The revelation has sent ripples through the developer community. On Wednesday, Google set its own internal deadline for 2029 to complete its migration to post-quantum encryption, warning that “quantum frontiers” are approaching faster than expected.
Crypto entrepreneur Nic Carter remarked on Thursday that standard elliptic curve cryptography is on the “brink of obsolescence.” While the Ethereum Foundation released a post-quantum roadmap in February, including plans to update validator signatures and account proofs, critics argue that the Bitcoin development community has been slower to address the looming threat.
Google’s primary recommendation to the cryptocurrency community is immediate action. Rather than waiting for hardware to reach full maturity, the search giant urges blockchains to begin the transition to PQC now to ensure long-term stability before the first cryptographically relevant quantum computer (CRQC) becomes a reality.