Although quantum computing remains a largely theoretical threat to blockchain for now, some projects are already preparing for this eventuality.
Fintech company Ripple has released a detailed four-phase roadmap to make the XRP Ledger, a decentralized layer 1 blockchain, quantum-resistant, with the goal of reaching full maturity by 2028. XRP, the world’s fourth-largest digital asset by market capitalization, is the native token of the XRP Ledger. Ripple’s solutions use XRP Ledger, XRP and other digital assets. Ripple is also one of several developers building on and contributing to the XRP Ledger (XRPL).
Ripple’s announcement comes weeks after Google warned that a quantum computer could potentially attack Bitcoin, the world’s largest blockchain, with less computing power than previously estimated, prompting some analysts to suggest 2029 as Q-Day, the so-called deadline for building defenses against such a machine. Bitcoin developers are also already working on measures to mitigate risk.
Let’s first understand the threat to XRPL and then discuss the four-phase plan.
Quantum risks for XRPL
A quantum computer has three implications for the XRP Ledger, and these apply to most other blockchains as well.
First, every time an XRPL account signs a transaction, its public key becomes visible on the blockchain. It’s like writing your mailing addresses on the outside of an envelope, allowing anyone to see where it came from, but without the private key, they still can’t see what’s written inside.
However, a quantum computer can reverse engineer the private key from the exposed public key, thereby emptying your coin holdings.
Second, accounts that hold coins for long periods of time have the highest risk. The longer the public key remains on the chain, the more time a future quantum attacker will have to target it.
Finally, the team added that building quantum-resistant systems is not only a technical challenge but also an operational one, as it is linked to every XRP holder and every application built on the XRP Ledger.
Collectively, these elements warrant a structured response.
The four-phase plan
Phase 1, called Q-Day preparation, is an emergency measure designed to protect exposed public keys and long-held accounts if quantum computers arrive faster than expected.
In this case, Ripple will implement what it calls a radical change: classic public-key signatures will no longer be accepted by the network, forcing all funds to migrate to quantum-secure accounts.
This phase also aims to enable safe recovery for all account holders via zero-knowledge proofs, a way to mathematically prove that you own a key without revealing the key itself. This would allow holders to migrate funds even in a compromised scenario, ensuring that no one is left out.
Phase 2 is already underway and is expected to be completed in the first half of 2026. This involves Ripple’s applied cryptography team conducting a comprehensive quantum vulnerability assessment across the XRPL network and testing defenses suggested by the National Institute of Standards and Technology, the US government’s global standards-setting body for cybersecurity.
But these defenses come at a cost. For example, post-quantum cryptography uses larger keys and signatures, which can put strain on the ledger. The team is therefore also working on compromises and system changes that might be necessary.
To accelerate this phase, Ripple has partnered with quantum security research firm Project Eleven for validator-level testing, benchmarking of developer networks, and early custody wallet prototypes.
Phase 3whose completion is planned for the second half of 2026, involves a controlled integration of post-quantum measurements. During this phase, Ripple will begin integrating quantum-resistant signatures alongside existing ones on its developer testnet. This will allow developers to test and develop the new cryptography without disrupting the live network and existing users.
This phase therefore directly responds to the third implication that migration, although it represents a giant operational effort, should not break what already works.
At the same time, the work goes beyond simply replacing current signing methods. The team is rethinking the broader cryptography that underpins XRPL and exploring quantum-resistant approaches to privacy and secure data processing, which are important for compliant tokenization and features such as confidential transfers.
“This phase is where experimentation meets system design. We don’t just ask “what works cryptographically?” We ask ourselves “what works for XRPL at scale?” “, said the team.
Phase 4 marks the complete transition from experimentation to full deployment, with a goal of completion by 2028. “We will design, build and deliver a new amendment to the XRPL ecosystem for native post-quantum cryptography and begin the network’s transition to PQC-based signatures at scale,” the Ripple team said.
The four phases mean the migration path could be seamless and significantly less painful, which could be a material advantage as Q-day approaches.
