One-Third of Bitcoin Exposed to Quantum Computing

Blockstream CEO Adam Back has taken direct aim at Ethereum's original design, calling it an 'obviously broken architecture.' In a post on X on October 10 (local time), he criticized Ethereum while touting Bitcoin's UTXO (unspent transaction output) model. In his reply on X, Back claimed that Ethereum developers simply reimplemented Ethereum around the 'obviously broken architecture' at its core. He assessed that the developers were young and naive, lacking both experience and wisdom. However, no public evidence—such as links, dates, or copies of conversations—was found to back up Back's claim that he specifically warned about the account model's problems before Ethereum's launch in July 2015.

Back's criticism of Ethereum is a long-standing pattern. In 2019, he compared Ethereum to 'Theranos,' a nod to the executive convicted of fraud, and in August 2020, he grouped Ethereum with controversial projects like BitConnect and OneCoin while criticizing the pre-sale of part of the ETH supply.

UTXO vs. account model: exposure patterns diverge. The structural difference translates directly into data security. Bitcoin keeps most of its coins bound to public key hashes (wallet address information that can safely be shown to others) and only reveals the public key when spending; well-designed wallets send any remaining balance to a new address, turning the exposed key into an empty envelope. Ethereum, by contrast, maintains a balance at a single address like a bank account, so once a transaction is made, the public key remains exposed for the entire life of the account. According to Michael Gertkin of Fireblocks, about a third of all Bitcoin already sits in wallets with exposed public keys.

Back's remarks came shortly after Ethereum Foundation researcher Justin Drake issued his 'bunker mode' warning on October 7. Drake warned that AI could, in a worst-case scenario, find ways to break the cryptographic technology protecting wallets within months, urging large holders to consider gradually moving their funds to new addresses.

Bitcoin (UTXO) and Ethereum (account-based) each have their own trade-offs, including parallel processing versus state constraints, and flexibility in implementing smart contracts (self-executing contract programs). On this, Coin Review noted that evaluations flatly declaring one structure 'broken' involve both technical and political perspectives.