Ripple is preparing the XRP Ledger (XRPL) for post-quantum cryptography well before a quantum computer capable of breaking today's public-key systems becomes a reality. "The goal is not to wait until quantum computing becomes an immediate threat," RippleX Senior Director of Engineering Ayo Akinyele told CoinDesk.

Researchers use the term "Q-Day" to describe the point at which a quantum computer can break the public-key cryptography used by production systems. No publicly known machine has reached that capability. Even so, preparation efforts have become more visible across major networks: Bitcoin recently tested two different quantum-security approaches, and Ethereum has moved quantum safety higher in its architectural planning. The work also draws on a broader standards effort: the U.S. National Institute of Standards and Technology ran an open competition for years and published its first finalized post-quantum cryptographic standards in 2024, giving networks a common reference point as they plan migrations.

An AI discovery complicates the choice of replacement cryptography

A separate development has complicated the selection of post-quantum algorithms. Anthropic's Claude Mythos Preview discovered an improved key-recovery attack against HAWK, a post-quantum signature candidate under consideration by the National Institute of Standards and Technology.

For the smallest HAWK-256 configuration, the expected attack work fell from approximately 2^64 operations to 2^38 — a reduction of roughly 67 million times. The model produced the result after about 60 hours, according to Anthropic's research report.

HAWK was never deployed on XRPL or any other production system, so the finding did not expose live accounts. What it demonstrated is how quickly a candidate can lose ground even after surviving years of expert review. AI does not bring Q-Day closer, but it can disqualify proposed defenses sooner. XRPL therefore needs more than one secure replacement for its current signatures — it needs a reliable way to change cryptography again if later research weakens the first choice.

Why exposed public keys create the risk

XRPL currently relies on elliptic-curve signatures to prove that an account holder authorized a transaction. Signing reveals the public key used to verify that authorization. A sufficiently capable quantum computer could theoretically calculate the corresponding private key from the public key, allowing an attacker to produce signatures that satisfy the network's existing rules.

The threat is not practical today. The concern is the time required to move active accounts away from exposed classical keys before such an attack becomes feasible. Cryptographers also describe a "harvest now, decrypt later" pattern, in which data captured today could be attacked later once capable quantum hardware exists — which is why ledger designs with long-lived public keys treat migration timelines, not just current capability, as the relevant risk.

XRPL can rotate the key without replacing the account

An XRPL account address and the key authorized to control it are separate. Accounts have a master key pair, but they can also assign and later replace a regular key through a SetRegularKey transaction. The address remains unchanged after another signer is assigned, and balances, trust lines, settings, and ledger history stay connected to the same account.

During a planned post-quantum migration, that separation could reduce the need to transfer assets solely to adopt stronger cryptography. This could spare users:

• Creating and registering another account address
• Moving every asset during the migration
• Updating addresses across connected financial services
• Rebuilding account history around another identity

There is a limitation, however: XRPL can rotate only into signature systems mainnet already recognizes. Accounts cannot select a post-quantum signer until developers implement one and the network activates it.

Keeping the same address also works best when migration begins before an emergency. Ripple's contingency planning allows for a harder response if classical signatures fail unexpectedly, potentially requiring funds to move under post-quantum protection.

Sui is examining the same user problem through a different design. Its planned post-quantum signers could preserve existing account addresses, showing why account continuity is becoming part of migration planning across multiple networks.

Two possible migration scenarios

Ripple's original post-quantum roadmap prepares for an orderly transition while keeping an emergency route available if quantum hardware advances faster than expected.

A planned transition

Ripple plans to compare several NIST-standardized signature schemes against real XRPL workloads. Security is only one criterion: public-key size, signature size, and verification speed determine whether a candidate can operate without placing excessive pressure on ledger storage or transaction processing. This matters because post-quantum signature schemes generally produce larger keys and signatures than the elliptic-curve systems they would replace, so performance trade-offs weigh directly on ledger capacity.

Work with Project Eleven includes Devnet benchmarking, validator tests, and an early custody-wallet prototype. Candidate post-quantum signatures are expected to operate alongside existing systems during this stage. That overlap would give service providers time to update their signing infrastructure before classical signatures are retired, and would reveal whether the new format creates problems for transaction throughput or validator hardware.

Ripple is targeting full post-quantum readiness by 2028, although that target does not guarantee when a mainnet amendment will activate.

An emergency recovery

The second scenario begins if quantum hardware threatens classical signatures before the planned transition is ready. XRPL could stop accepting the affected signatures, but a valid classical private key might no longer establish who owned an account first — an attacker could possess a mathematically correct key calculated from public information already visible on the ledger.

Ripple is investigating whether seed-derived information and post-quantum zero-knowledge proofs could provide a separate ownership test. That method remains exploratory; no finished recovery specification or user process has been released.

Mainnet activation requires validator agreement

Individual accounts can choose an authorized key, but they cannot decide which signature algorithms XRPL accepts. Adding another verification system changes the network's transaction rules and therefore requires an amendment. Under the official XRPL amendment process, a protocol change must maintain more than 80% support from trusted validators for two weeks before activation, and the new code must already be included in the software those validators run. Servers lacking support after activation can become amendment-blocked because they can no longer process the ledger under the updated rules.

Akinyele told CoinDesk that the transition would reach beyond swapping one algorithm for another. The supporting infrastructure must let accounts and financial services adopt new security without interrupting payments or access to funds.

The HAWK finding explains why that process must be repeatable. An algorithm can survive extensive review and still be weakened later, so XRPL cannot build its migration around the assumption that the first post-quantum system it selects will be the final one.

What XRP holders should watch today

Ripple has not asked XRP holders to move funds, create replacement accounts, or rotate into post-quantum keys — ordinary XRPL accounts do not yet have that option on mainnet. Holders are advised to:

• Not trust unsolicited "quantum-safe" wallet instructions
• Continue protecting seeds and signing devices normally
• Separate Devnet experiments from mainnet protection
• Use only officially supported future migration tools
• Follow amendment votes through official XRPL sources

Four developments would signal that migration is approaching: a selected signature scheme, published performance benchmarks, supported wallet tools, and a live amendment vote. Until those appear, XRP holders have no quantum-specific transaction to perform.

XRPL can replace the key controlling an account without rebuilding the account around it, which could prevent an orderly security upgrade from turning into a mass address migration. The roadmap succeeds when ordinary accounts can adopt the new signer through supported software on a network whose validators already agree on the rules.

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