The cybersecurity working group of the G7 has urged governments and businesses worldwide to begin the immediate transition to post-quantum cryptography, warning that the advancement of quantum computing represents an imminent risk to current encryption systems. This guidance carries direct implications for cryptocurrency networks, exchanges, and custodians facing potentially costly system upgrades before quantum computers become capable of compromising existing cryptographic protections.
G7’s call to action on quantum threat
On September 3, 2026, the G7 working group released a document titled “Preparing for the Post-Quantum Era: A Call to Action.” The report categorizes quantum computing as a significant cybersecurity risk that organizations must address in advance of the arrival of quantum machines capable of breaking widely used cryptography.
Although the G7 report does not mention cryptocurrencies specifically, the security of blockchain technologies is closely linked to public-key cryptography. Since cryptocurrencies rely on these algorithms to protect transactions and manage funds, the quantum threat extends to the crypto industry and its entire infrastructure.
Although the exact timeline is uncertain, several recent advances suggest an anticipation of the development of quantum computers able to break widely used public-key cryptography mechanisms.
G7 Cybersecurity Working Group
A key concern highlighted by the working group is the “harvest now, decrypt later” approach, where attackers collect encrypted data today and wait to decrypt it once quantum capabilities become available. For blockchains, where public keys and transaction history are permanently visible, this could lead to retrospective attacks even years after initial transactions.
ETH
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AAPLHarvest now, decrypt later.
G7 Cybersecurity Working Group
The G7 has advised nations and organizations to raise awareness, establish national strategies, invest in research, promote public and private sector collaboration, and set procurement policies focused on post-quantum cryptography.
Europe’s post-quantum deadlines
The European Union has already set binding requirements through its Coordinated Implementation Roadmap for the Transition to Post-Quantum Cryptography. Adopted in June 2025, the policy mandates that all member states start transitioning by the end of 2026, with high-risk entities required to complete migration before 2030.
These regulatory changes mean post-quantum cybersecurity is now essential for compliance and competitiveness. Companies lacking clear migration plans may face legal hurdles or lose their edge in the evolving regulatory landscape.
Various approaches by Bitcoin and Ethereum
Bitcoin developers are exploring BIP-360, a soft fork proposal known as Pay-to-Merkle-Root, which aims to reduce long-term quantum vulnerabilities. This measure seeks to eliminate key-path spending mechanisms exposed to quantum attacks, but its creators acknowledge that some risks, especially those involving mempool transactions, require further mitigations. An activation date for BIP-360 has not yet been established.
Ethereum has outlined a broader post-quantum security plan. Vitalik Buterin’s roadmap for February 2026 highlighted four crucial areas for upgrade: validator BLS signatures, KZG commitments, ECDSA account signatures, and zero-knowledge proofs on the application layer. Ethereum targets core post-quantum infrastructure by 2029, although the transition could extend beyond this date.
A significant challenge for both networks is the increased size of post-quantum digital signatures. For instance, a standard secp256k1 ECDSA signature is 64 bytes, while the Dilithium-5 post-quantum scheme requires approximately 4,595 bytes, and the finalized ML-DSA-87 standard uses about 4,627 bytes. Larger signatures may drive up storage, bandwidth, and transaction fees.
| Cryptographic Standard | Signature Size |
|---|---|
| secp256k1 ECDSA | 64 bytes |
| Dilithium-5 | 4,595 bytes |
| ML-DSA-87 | 4,627 bytes |
Mini dictionary: BIP-360, or Bitcoin Improvement Proposal 360, introduces Pay-to-Merkle-Root—a protocol change meant to future-proof Bitcoin against quantum computer attacks by restructuring how spending conditions are recorded on the blockchain.
Migration risks overshadow quantum timeline
Industry observers note the near-term risk lies less with the timing of a quantum breakthrough and more with the challenges involved in the transition: protocol development, governance debates, increased infrastructure requirements, larger keys, and exposure of public keys from older wallets.
Research by Google Quantum AI in March 2026 argued that compromising 256-bit elliptic-curve cryptography may be easier than earlier assumed. Google also disclosed that its own post-quantum migration will conclude by 2029.
NIST has issued a draft recommending that 112-bit ECDSA be eliminated after 2030 and that all use of ECDSA cease after 2035, signaling a clear timeline for the industry to adopt new cryptographic standards.
Cryptopolitan previously indicated that institutional standards and custody requirements may soon require quantifiable post-quantum readiness, potentially making a robust migration framework a distinguishing factor for investors.
