The rise of quantum computing has sparked concerns about the potential risks it poses to legacy blockchains. For XRP, experts suggest that its architecture may be better equipped to handle these risks than Bitcoin's. This is due in part to the XRP Ledger's open-source, decentralized nature and its use of a unique feature set.

Let's break it down. The primary concern with quantum computing is its potential to reverse-engineer private keys from exposed public keys, allowing attackers to drain funds.

Typically, public keys are exposed when sending transactions, making account activity a key factor in quantum vulnerability. Recently, a quantum vulnerability audit of the XRP Ledger found that around 300,000 accounts holding 2.4 billion XRP have never sent funds, 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 audit found two such accounts holding 21 million XRP, which, although significant, accounts for only 0.03% of the circulating supply.

The XRP Ledger's account-based system and signing key rotation feature allow users to swap their signing key without moving funds, reducing vulnerability. However, this feature is not a foolproof solution, particularly for long-dormant accounts.

Another defense against quantum risk is the 'escrow feature,' which locks funds with a time lock, making them safe due to logic rather than cryptography. While this protects the funds, the account that locked them can still carry quantum risks.

In comparison, the quantum threat to Bitcoin appears more severe due to its larger scale and the use of P2PK, which exposes public keys directly in transaction outputs. Approximately 6.9 million BTC, or nearly 35% of Bitcoin's circulating supply, are vulnerable, including Satoshi Nakamoto's 1 million BTC. Bitcoin holders face a structural problem, as the blockchain lacks a key rotation feature, forcing them to move funds to a new address and exposing the public key of the old address. Although this risk is largely theoretical, it highlights the relative vulnerability of Bitcoin holders.

Bitcoin developers have already begun proposing solutions to develop quantum resistance.