The recent focus on quantum computing, sparked by Google's assertion that a sufficiently powerful machine could compromise legacy blockchains with relatively less computational power than initially thought, has brought attention to the potential vulnerabilities of various cryptocurrencies. For XRP holders, the answer to the question of vulnerability is nuanced.
Experts suggest that XRP's architecture may be better positioned to withstand quantum attacks than Bitcoin's. XRP operates on the XRP Ledger (XRPL), an open-source, decentralized blockchain used by Ripple, a fintech company, to facilitate cross-border transactions. Let's delve into the details step by step. The primary threat to blockchains from quantum computing lies in the potential for a powerful quantum computer to reverse-engineer a user's private key from their exposed public key, thereby gaining access to their funds.
Typically, a user's public key is exposed when they send a transaction, making their account activity a factor in quantum vulnerability, rather than their balance or how long they've held an address. Recently, a quantum vulnerability audit of the XRP Ledger found that approximately 300,000 XRP accounts, holding about 2.4 billion XRP, have never sent funds and thus have never exposed their public keys to the network, making them quantum-safe by default.
However, there are dormant 'whale' accounts that have transacted in the past, exposing their public keys, but these are relatively few and hold a small percentage of the circulating supply. The XRP Ledger's feature of allowing signing key rotation without moving funds provides an additional layer of security, though this is not foolproof, especially for long-dormant accounts. Another feature, the escrow function with a time lock, protects funds logically rather than cryptographically, preventing withdrawal until a specified time has passed.
While this protects the funds, the account itself remains vulnerable to quantum risks. In comparison, the quantum threat to Bitcoin appears more significant due to the sheer scale of potentially vulnerable coins, including Satoshi Nakamoto's untouched 1 million BTC, and the lack of a key rotation feature in Bitcoin's blockchain. This forces Bitcoin holders to move funds to new addresses to protect them, exposing the old address's public key during the transaction process.
Although the risk is still theoretical, and Bitcoin developers are working on quantum resistance proposals, the structural vulnerability of Bitcoin compared to XRP is notable.