X user @cprkrn said he regained access to 5 BTC bought in 2015 after the coins sat untouched for 11 years. At the time of his post, he valued the holdings at roughly $400,000. The recovery did not come from faster password cracking hardware. It came after he fed years of old files and devices into Claude.
An old address sat inactive for more than a decade
Based on the address he shared, 14VJySbsKraEJbtwk9ivnr1fXs6QuofuE6, the wallet first received 0.25462585 BTC in December 2014 and then another 5 BTC in April 2015. He said Bitcoin was trading near $250 at the time, putting the purchase cost for the 5 BTC at about $1,250. The address then showed no outgoing activity for more than 11 years.
@cprkrn said he had written down a mnemonic phrase back then, but for unknown reasons it never let him open the wallet. The main obstacle was Blockchain.com’s “second password” feature. In that setup, a user can set one password for login and another one to encrypt the private keys inside the wallet file, with no server-side copy kept by the company.
Eight weeks and 3.4 trillion password attempts led nowhere
Before turning to AI, he spent eight weeks trying standard wallet recovery methods. He first used btcrecover, an open-source Python tool that runs dictionary attacks and rule-based password variations on CPUs at roughly 300,000 guesses per second. That stage tested about 34 billion combinations without success.
He then moved to Hashcat and rented RTX 4090 GPUs through Vast.ai, pushing speed to around 148 million guesses per second. After two months, the total reached about 3.4 trillion password attempts. It still failed to unlock the second password.
Claude connected an old backup file with a forgotten mnemonic
The breakthrough came after he handed over data from his old college-era computer. According to his account, Claude worked across 2 Macs, 2 external hard drives, 1,684 self-directed Twitter DM messages, paper notebooks, exported Apple Notes files, iCloud Mail, and a Gmail mbox export larger than 1GB.
Claude eventually surfaced an older wallet backup downloaded in December 2019, a file he said he had forgotten existed. He also found an old mnemonic phrase in a college notebook. That phrase could unlock the backup, and the backup contained the private keys that gave him control of the wallet again.
The turning point was file discovery, not a crypto break
The episode did not involve a technical break in Bitcoin or the wallet’s encryption design. The mnemonic already existed, and the backup file had been sitting on storage all along. What changed was the ability to search through years of scattered records and identify which pieces were worth testing together. In this case, Claude functioned less as a password-cracking engine and more as a tireless archival assistant.