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QUANTUM THREAT BRIEFING — ECDLP VULNERABILITY REPORT 2026

QUANTUM THREAT BRIEFING — ECDLP VULNERABILITY REPORT 2026

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Threat Brief

ECDLP · Quantum Vuln · 2026

Overview

Key Findings
The Numbers
Attack Types

By Chain

Bitcoin
Ethereum
Other Chains

Policy

Dormant Assets
PQC Migration

Reference

Glossary

Authors

Source Paper

Public Disclosure — March 30, 2026

Quantum Computers Will Break Blockchain Cryptography. Here's What We Now Know.

A plain-language guide to the most consequential cryptographic threat assessment ever published for cryptocurrency — by Google Quantum AI, Stanford, and the Ethereum Foundation.

Authors
Babbush, Zalcman, Gidney et al.

Institution
Google Quantum AI + Stanford + ETH Foundation

Published
March 30, 2026

Threat Level
Critical — Near-Term

01 — Key Findings

What This Paper Actually Proved

This isn't theoretical. Google's team built quantum circuits that can crack Bitcoin's cryptography and proved it with cryptographic evidence — a zero-knowledge proof that the circuits exist and work, without publishing the blueprints. Here are the five things that make this paper different from everything that came before it.

1. The qubit count dropped by 20x

Every previous estimate said you needed millions of physical qubits to break Bitcoin's encryption. The best prior work (Litinski 2023) needed roughly 9 million. Google got it down to under 500,000 — on standard superconducting hardware with realistic error rates. That's not a minor improvement. That's the threat moving from "maybe in 20 years" to "when someone builds the machine."

2. Active transactions are at risk, not just stored funds

This is the new finding nobody saw coming. At 9 minutes per private key derivation, a quantum attacker has a 41% chance of stealing your Bitcoin before your transaction even confirms. You broadcast a transaction. Your public key is now visible in the public mempool. The attacker grabs it, cracks it, broadcasts their own transaction with a higher fee, and beats you to the block. This is called an "on-spend attack" — and it changes everything about how you think about the threat.

3. They used a zero-knowledge proof to disclose without weaponizing

For the first time in cryptanalysis history, a team published a cryptographic proof that their attack circuits are real and meet their claimed resource specs — without publishing the actual circuits.…