Blockstream CEO Adam Back spoke at Paris Blockchain Week with a point that has long been discussed but rarely stated so directly: a future transition of Bitcoin to quantum-resistant addresses will effectively reveal whether Satoshi Nakamoto’s coins are still accessible. Any holder of vulnerable coins will be forced to move them to a new address format — or risk losing access to them forever.
“This transition to a post-quantum address format may show us how many of Satoshi’s coins are still accessible,” Back said.
According to his estimates, Bitcoin’s creator may have owned between 500,000 and 1 million BTC. Data from Arkham links wallets holding 1.09 million bitcoins to Nakamoto — worth around $81.6 B at the time of Back’s remarks. Coins that remain on old addresses after the migration, in his view, can reasonably be considered lost.
The Quantum Threat Isn’t Tomorrow
There’s no immediate cause for concern. Back argues that a real quantum breakthrough capable of threatening Bitcoin signatures is at least 20 years away.
“Today’s quantum computers are less powerful than a $5 calculator, and their practical limitations — especially energy consumption — become more severe as systems scale,” he said.
According to him, Bitcoin developers and holders have enough time to design a post-quantum standard based on hash-based signatures and transition gradually. The migration would give users ample time to move their funds independently.
Back Is Satoshi?
Notably, Back speaks about Satoshi’s coins not purely as an outside observer. Investigative journalist John Carreyrou previously published a report linking Nakamoto’s identity to him.
Carreyrou analyzed cypherpunks mailing list archives, early developer correspondence, and thousands of messages from cryptographic archives, including emails revealed during the court case against Craig Wright. Among the evidence: Back’s authorship of Hashcash, the system that underpins Bitcoin’s mining mechanism and is directly cited in the Bitcoin white paper. He also pointed to similarities in rare terminology, grammar, and a distinctive mix of British and American English.
The journalist also noted that during Bitcoin’s launch period, Back completely disappeared from public discussions about digital money — despite previously writing about it regularly — and only returned to the ecosystem after Satoshi vanished in 2011. Back denied all allegations, dismissing the similarities as coincidental.