The rise of quantum computing has sparked concerns about the potential risks to blockchain security. Recently, Google announced that a powerful enough quantum computer could compromise legacy blockchains with less effort than previously thought.
For XRP holders, experts offer a nuanced assessment, suggesting that XRP's architecture may be better equipped to withstand quantum attacks than Bitcoin's. XRP operates on the XRP Ledger, an open-source, decentralized blockchain that facilitates cross-border transactions through Ripple, a fintech firm.
Let's break down the details step by step. The quantum threat stems from the fact that a sufficiently powerful machine using Shor's algorithm could potentially reverse-engineer a private key from an exposed public key, allowing an attacker to drain funds. Typically, a public key is exposed when a transaction is sent, and an account's activity, rather than its balance or age, determines its quantum vulnerability.
A recent audit of the XRP Ledger found that around 300,000 accounts, holding approximately 2.4 billion XRP, have never sent funds and thus have not 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 more vulnerable.
The audit identified 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, which allows users to swap signing keys without moving funds, provide additional protection.
However, this feature is not foolproof, particularly for long-dormant accounts that may have lost keys or are no longer active. Mayukha Vadari, a staff software engineer at Ripple, highlighted the escrow feature as another defense against quantum risk, as funds locked in escrow with a time lock are safe due to logical rather than cryptographic protections.
In comparison, the quantum threat to Bitcoin appears more severe due to the sheer scale of vulnerable coins. Approximately 6.9 million BTC, including Satoshi Nakamoto's 1 million BTC, are vulnerable, accounting for nearly 35% of Bitcoin's circulating supply.
This is largely due to the use of the P2PK format, which exposes public keys directly in transaction outputs. Bitcoin's lack of a key rotation feature also leaves holders more vulnerable, as they must move funds to a new address to protect them, briefly exposing the old address's public key to potential quantum attacks.
While Bitcoin developers have proposed solutions to develop quantum resistance, XRP's unique features and lower exposure to quantum risks make it a more secure option for now.