The rise of quantum computing has sparked concerns about the security of legacy blockchains, with Google warning that a powerful enough machine could compromise them with less effort than previously thought. For XRP holders, experts offer a more nuanced assessment, suggesting that XRP's architecture provides better protection against quantum threats than Bitcoin's. This is due in part to the XRP Ledger's open-source, decentralized nature and its use by fintech firm Ripple for cross-border transactions.
Let's examine the details step by step. The primary concern is that a sufficiently powerful quantum computer using Shor's algorithm could potentially reverse-engineer a user's private key from their exposed public key, thereby draining their funds. Typically, a user's public key is exposed when they send a transaction, and their wallet address is generated from this public key. However, XRP Ledger's validator, Vet, recently conducted a quantum vulnerability audit and found that around 300,000 XRP accounts, holding approximately 2.4 billion XRP, have never sent funds and thus have never exposed their public keys to the network.
These accounts are inherently quantum-safe. In contrast, dormant 'whale' accounts that have transacted in the past and exposed their public keys are at risk, but Vet found only two such accounts on the XRP Ledger, holding a total of 21 million XRP, which is just 0.03% of the circulating supply. The XRP Ledger's account-based system and key rotation feature allow users to swap their signing key without moving funds, providing an additional layer of security.
Mayukha Vadari, a staff software engineer at Ripple, also pointed to the 'escrow feature' as a defense against quantum risk, as funds locked in escrow with a time lock are protected by logic rather than cryptography. In comparison, the quantum threat to Bitcoin appears more significant due to its larger scale and the fact that a substantial portion of early bitcoin was mined using a format that exposed public keys directly. Approximately 6.9 million BTC are estimated to be vulnerable, which is nearly 35% of Bitcoin's circulating supply.
Unlike XRP, Bitcoin lacks a key rotation feature, leaving holders with the option to move funds to a new address, but this process temporarily exposes the public key of the old address to potential quantum attacks. While Bitcoin developers have proposed developing quantum resistance, XRP's design and features seem to provide better protection against quantum threats at present.