While 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-proof, aiming to reach full readiness by 2028. XRP, the world’s fourth-largest digital asset by market capitalization, is the native symbol of the XRP Ledger. Ripple’s solutions use the XRP Ledger, XRP and other digital assets. Ripple is also one of many 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 the risk.
Let us first understand the threat to XRPL and then discuss the four phase plan.
Quantitative risks for XRPL
A quantum computer has three implications for the XRP Ledger, and these apply similarly to most other blockchains.
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 so everyone can see where it’s from, but they still can’t see what’s inside without the private key.
However, a quantum computer can reverse engineer the private key from the exposed public key, draining your coin supply.
Second, accounts that have held coins for long periods of time are the highest risk. The longer the public key sits on the chain, the more time a future quantum attacker has to target it.
Finally, the team added that building quantum-resistant systems is not only a technical challenge, but an operational one, as it is linked to every XRP holder and every application built on the XRP Ledger.
Taken together, these things warrant a structured response.
The four-phase plan
Phase 1, called Q-Day Readiness, is an emergency measure designed to protect exposed public keys and long-lived accounts if quantum computers arrive sooner than expected.
In that case, Ripple will implement what it calls a hard shift: Classic public key signatures will no longer be accepted by the network, requiring all funds to be migrated to quantum-safe accounts.
This phase also looks at enabling secure recovery for all account owners via zero-knowledge proofs, a way to mathematically prove 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 gets locked out.
Phase 2 is already underway and is targeted for completion in the first half of 2026. It involves Ripple’s applied cryptography team performing a full quantum vulnerability assessment across the XRPL network and testing defenses proposed by the National Institute of Standards and Technology, the US government’s global cybersecurity standards body.
But these defenses are not without cost. For example, post-quantum cryptography uses larger keys and signatures, which can burden the ledger. So the team is also working through the trade-offs and what system changes might be needed.
To accelerate this phase, Ripple has teamed up with quantum security research firm Project Eleven for validator-level testing, developer network benchmarking, and early depo-pung prototypes.
Phase 3targeted for completion in the second half of 2026, involves controlled integration of post quantum measures. In this phase, Ripple will begin integrating quantum-resistant signatures alongside existing ones on its developer test network. It will allow developers to test and build against the new cryptography without disrupting the live network and existing users.
This phase therefore directly addresses the third implication that migration, although a huge operational effort, must not break what already works.
At the same time, the work goes beyond simply replacing today’s signing methods. The team is rethinking the broader cryptography underpinning XRPL and exploring quantum-resistant approaches to privacy and secure computing, which are important for compliant tokenization and features such as confidential transfers.
“This phase is where experimentation meets system design. We’re not just asking ‘what works cryptographically?’ We’re asking ‘what works for XRPL at scale?'” the team said.
Phase 4 marks the full transition from experiment to full implementation, targeting completion in 2028. “We will design, build and propose a new change to the XRPL ecosystem for native post-quantum cryptography and begin transitioning the network to PQC-based signatures at scale,” Ripple’s team said.
The four stages mean that the migration path can be hassle-free and significantly less painful, which can be a significant advantage as the clock ticks down to Q-day.
