While quantum computing remains a largely theoretical threat to blockchain for now, some projects are already preparing for that 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 readiness by 2028. Ripple solutions use the XRP Ledger, XRP and other digital assets. Ripple is also one of the many developers building 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, leading some analysts to suggest 2029 as Q-day, the so-called deadline for building defenses against such a machine. Bitcoin developers are also working on measures to mitigate the risk.
Let us 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 equally 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 postal addresses on the outside of an envelope, allowing anyone to see where it came from, but still can’t see what’s written inside without the private key.
However, a quantum computer can reverse engineer the private key from the exposed public key, depleting its coin reserves.
Second, accounts that have held coins for long periods of time are the highest risk. The longer the public key remains on the chain, the more time a future quantum attacker will have to attack it.
Lastly, the team added that building quantum-resistant systems is not only a technical challenge but also an operational one, as it is tied to every XRP holder and every application built on the XRP Ledger.
Taken together, these things justify a structured response.
The four-phase plan
Phase 1, Called Q-Day preparedness, it is an emergency measure designed to protect exposed public keys and long-held accounts if quantum computers arrive faster than expected.
In that case, Ripple will implement what it calls a radical change: the network will no longer accept classic public key signatures, requiring all funds to migrate to quantum-safe accounts.
This phase also seeks to enable secure recovery for all account owners through 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 scheduled for completion in the first half of 2026. It involves Ripple’s applied cryptography team conducting a full quantum vulnerability assessment across the entire XRPL network and testing defenses suggested by the National Institute of Standards and Technology, the US government’s global standards body for cybersecurity.
But those defenses come at a cost. For example, post-quantum cryptography uses larger keys and signatures, which can overload the ledger. Therefore, the team is also looking at trade-offs and system changes that might be necessary.
To accelerate this phase, Ripple has partnered with quantum security research firm Project Eleven to conduct validator-level testing, developer network benchmarking, and early custodial wallet prototypes.
Phase 3scheduled for completion in the second half of 2026, involves the controlled integration of post-quantum measurements. In this phase, Ripple will begin integrating quantum-resistant signatures alongside existing ones on its developer testnet. It will allow developers to test and build with the new cryptography without disrupting the active network or existing users.
Therefore, this phase directly addresses the third implication that migration, although 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 underpinning XRPL and exploring quantum-resistant approaches to privacy and secure data processing, which are important for supported tokenization and functions 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 complete transition from experiment to full deployment, with the goal of completion by 2028. “We will design, build and propose a new amendment to the XRPL ecosystem for native post-quantum cryptography and begin transitioning the network to PQC-based signatures at scale,” the Ripple team said.
The four phases mean the migration path could be smooth and significantly less painful, which could be a material advantage as the clock ticks towards Q-day.
