The emergence of quantum computing has sparked concerns about the security of legacy blockchains, with Google suggesting that a powerful enough machine could compromise them with less effort than previously thought. For XRP holders, the situation is more nuanced, with experts arguing that XRP's architecture offers better protection against quantum threats than Bitcoin's. XRP operates on the XRP Ledger, an open-source, decentralized blockchain, and is used by Ripple for cross-border transactions. Let's examine the details step by step.
The primary threat to blockchains comes from the potential for a sufficiently powerful quantum computer to reverse-engineer private keys from exposed public keys, thereby draining funds. This vulnerability arises when a user sends a transaction, exposing their public key to the network. However, if a user only receives funds, their public key remains hidden, making their account quantum-safe by default. Recently, a quantum vulnerability audit of the XRP Ledger found that approximately 300,000 accounts, holding 2.4 billion XRP, have never sent any funds and are therefore quantum-safe.
In contrast, dormant whale accounts that have transacted in the past and exposed their public keys are more vulnerable. The audit discovered two such accounts holding 21 million XRP, which is only 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 protection.
However, this feature is not foolproof, as dormant accounts may not be able to utilize it. Mayukha Vadari, a staff software engineer at Ripple, highlighted the escrow feature as another defense against quantum risk, where funds locked with a time lock are safe due to logic rather than cryptography.
In comparison, the quantum threat to Bitcoin appears more significant, with a larger portion of the circulating supply vulnerable to attacks. Approximately 6.9 million BTC, including Satoshi Nakamoto's 1 million BTC, are at risk, which is nearly 35% of Bitcoin's circulating supply.
Bitcoin's lack of a key rotation feature leaves holders with limited options to protect themselves, making them more structurally vulnerable to quantum attacks.