The recent surge in interest in quantum computing, fueled by Google's assertion that a sufficiently powerful machine could compromise legacy blockchains with relative ease, has sparked a nuanced discussion among experts. They suggest that XRP's architecture may be more resilient to quantum threats than Bitcoin's.
This is largely due to the XRP Ledger's open-source, decentralized nature and its use by fintech firm Ripple for cross-border transactions. Let's delve into the details step by step.
The primary concern is that a powerful quantum computer running Shor's algorithm could potentially reverse-engineer a private key from an exposed public key, thereby draining funds. Typically, a public key is exposed when a transaction is sent, and the account activity, rather than the balance or the duration of holding an address, is what makes an account quantum-vulnerable. An 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, making them quantum-safe by default.
However, dormant 'whale' accounts that have transacted in the past and exposed their public keys are at risk. The XRP Ledger's feature allowing for the rotation of signing keys without moving funds provides an additional layer of security. Mayukha Vadari, a staff software engineer at Ripple, also highlighted the 'escrow feature' as a defense mechanism, where funds locked with a time lock are protected not by cryptography, but by logic, preventing withdrawal until a specified time has passed. In comparison, the quantum threat to Bitcoin appears more significant due to its scale and the lack of a key rotation feature, leaving holders more vulnerable to potential quantum attacks.