TL;DR:
This Monday, August 31, Circle warned that quantum computing narrows the gap to blockchain security faster than projected. The firm unveiled a technical monitoring tool after recording a 65% decrease in the computational requirements needed to breach the digital signature schemes predominant across the industry.
The cryptography protecting most blockchain transactions is getting easier to break.
That does not mean quantum computers are a threat yet. It means the gap between today’s quantum capability and the defenses securing blockchain signatures is getting smaller.
This new technical…
— Circle (@circle) August 31, 2026
The Bitcoin and Ethereum networks utilize the Elliptic Curve Digital Signature Algorithm (ECDSA) under the secp256k1 curve to authorize transfers. In 2017, academic literature estimated that breaking this scheme using Shor’s algorithm required approximately 2,330 logical qubits with error correction.
Data from the open ranking ecdsa.fail compiled by Circle indicates that this requirement dropped to 813 logical qubits by the close of August 2026. Artificial intelligence-assisted circuit optimization accounts for this reduction in required theoretical resources.
Quantum hardware is also reporting scaling milestones. Google demonstrated 105 logical qubits on its Willow processor, while QuEra published a technical roadmap outlining systems with over 1,000 logical qubits available via Amazon Braket cloud infrastructure by 2029.
According to technical analysis published by Circle Research, the combination of expanding hardware and more efficient attack circuits narrows the time window available to upgrade decentralized infrastructure.
ECDSA and Ed25519 signatures secure all transactions across major blockchains. According to official Circle documentation, any address that has signed and broadcasted a prior transaction has its public key exposed on the distributed ledger.
An adversary with access to a fault-tolerant quantum computer could derive the private key from that exposed public key. This scenario would compromise funds stored in accounts that have previously interacted with the network.
The technical transition will require structural adaptations across multiple software layers:
Custody systems: Modification of cryptographic libraries, cold storage solutions, and hardware signing devices.
Smart contract compatibility: Updates to elliptic curve-based signature verification functions such as ecrecover.
Hybrid schemes: Implementation of classical and post-quantum signatures in parallel to prevent operational disruptions.
Circle reported that its Layer 1, Arc, integrated technical support for SLH-DSA, one of the post-quantum standards formalized by the National Institute of Standards and Technology (NIST). The company maintains a hybrid model on Arc while evaluating interoperability across more than 30 chains where the USDC stablecoin operates.
To coordinate this transition without compromising global liquidity, the Circle Research team will keep its quantum gap tracker updated as new academic metrics and hardware milestones are published during the upcoming cryptographic audit cycle.
