The recent focus on quantum computing, fueled by Google's assertion that a powerful enough machine could compromise legacy blockchains with less effort than previously thought, has sparked concern among cryptocurrency holders. For XRP holders, experts offer a more nuanced assessment, suggesting that XRP's architecture may be better equipped to withstand quantum threats than Bitcoin's. XRP operates on the XRP Ledger, an open-source, decentralized blockchain, which is utilized by Ripple for facilitating cross-border transactions. Let's delve into the details step by step.
The primary threat to blockchains stems from the potential for a sufficiently powerful quantum computer to reverse-engineer private keys from exposed public keys, thereby allowing unauthorized access to funds. Typically, a user's public key is exposed during transactions, making their account activity a factor in quantum vulnerability, rather than their balance or the duration they've held an address.
A recent audit of the XRP Ledger found that approximately 300,000 accounts, holding 2.4 billion XRP, have never sent funds and thus have never exposed their public keys, rendering them quantum-safe by default. However, dormant 'whale' accounts that have transacted in the past and exposed their public keys are at risk, with two such accounts identified, holding 21 million XRP, which is only 0.03% of the circulating supply.
The XRP Ledger's feature allowing for the rotation of signing keys without moving funds provides an additional layer of security, although this is not a foolproof solution, especially for long-dormant accounts. Mayukha Vadari, a staff software engineer at Ripple, highlighted the 'escrow feature' as another defense mechanism, where funds locked with a time lock are safe due to logical constraints rather than cryptography.
In comparison, the quantum threat to Bitcoin appears more significant due to the large portion of early Bitcoin that was mined using a format that directly exposed public keys, including Satoshi Nakamoto's 1 million BTC. Approximately 6.9 million BTC, nearly 35% of Bitcoin's circulating supply, is estimated to be vulnerable, compared to XRP's 0.03%. Bitcoin holders face a structural problem in protecting their funds, as moving them to a new address exposes the old address's public key, making it vulnerable to quantum attacks during the transaction processing time.
While Bitcoin developers are working on proposals to develop quantum resistance, XRP's existing features may provide it with an advantage in terms of quantum security.