XRP Ledger Maps a Post-Quantum Upgrade Path to 2028

Planning for a Break That Has Not Happened Yet

Ripple has laid out a four-phase roadmap for making the XRP Ledger quantum-resistant, targeting native post-quantum signatures across the network by 2028. CoinDesk covered the plan on August 28, 2026, and Ripple's own engineering write-up sets out the phases in detail.

The framing worth noting is that Ripple is explicitly not treating this as a software upgrade. Its post says the migration touches performance, storage, usability, cryptography and protocol design simultaneously — which is the correct read, and the reason a roadmap exists instead of a patch note.

• Four phases targeting 2028 for native post-quantum signatures across the XRP Ledger
• Phase 1 is a Q-Day contingency designed to protect exposed public keys and long-dormant accounts if quantum capability arrives ahead of schedule
• NIST-recommended algorithms are being tested, with candidate post-quantum signatures expected to run alongside existing elliptic curve signatures on development networks during the second half of 2026
• The final stage needs an amendment and coordination among independent validators, which is a governance step as much as a technical one

What Is Q-Day, and Why Plan for It Now?

"Q-Day" is the shorthand for the point at which a quantum computer can break the elliptic curve cryptography that secures most blockchain accounts. Nobody knows when that is. The reason to act well ahead of it is that on a public ledger, exposed public keys are permanently visible — an account that has ever sent a transaction has published the material an attacker would eventually need.

That is what makes Phase 1 the interesting piece. It is an emergency lever rather than a feature: if classical cryptography breaks unexpectedly, the XRPL would enforce a hard cutover in which classical public-key signature standards stop being accepted network-wide, and funds must move to post-quantum secure accounts. Blunt, disruptive, and vastly better than the alternative.

Running Two Signature Schemes at Once

The intermediate phases have candidate post-quantum signatures operating in parallel with elliptic curve signatures on devnets and then testnets through mid-2026 and beyond. Ripple describes optimising for two goals at once: preserve what the XRPL does well today while the transition is built, and minimise disruption if the timeline compresses.

The engineering cost here is mostly size. Post-quantum signature schemes produce substantially larger signatures than the elliptic curve ones they replace, and on a ledger that competes on transaction throughput and settlement cost, that lands directly on the metrics users care about. Solving that without degrading the network is the actual hard problem, not selecting an algorithm — NIST has already done the selection work.

How This Compares to Other Chains

Post-quantum planning has become a live thread across crypto infrastructure over the past few months rather than a theoretical exercise. We covered MARA launching a Bitcoin foundation aimed at quantum resistance and BIP-360 wallets, and a Google Quantum AI paper spotlighting Algorand's Falcon-based approach as a model for how a chain can migrate.

Ripple's version is distinguished mainly by having a date attached and a published phase structure. Whether 2028 holds is a separate question — the final stage requires an amendment vote and validator coordination, and the XRPL's amendment process has historically moved at its own pace. The ledger has been active on this front generally, having recently added confidential token transfers via amendment, and Ripple has been hardening the ledger through AI red-teaming alongside it.

For anyone holding XRPL assets, the practical takeaway is dull and useful: nothing to do today, but the eventual migration will involve moving funds to new account types, and that will be a real operational event when it lands.

Sources: Ripple — August 2026; CoinDesk — August 28, 2026.