Encrypted Wallet.dat Recovery After Quick Format: Hex Extraction Versus File Recovery
IndeterminateHardware device was lost or destroyed — whether access was recovered is not documented.
In November 2020, a user ('fajja') on BitcoinTalk discovered old hard disks that had been quick-formatted years earlier, containing Bitcoin Core wallet.dat files and possibly Litecoin wallets from 2014–2015. The user had been furloughed and was revisiting archived storage. Quick format removes file system references while leaving underlying sector data intact—a technically recoverable state if no new data has overwritten the sectors.
Fajja first attempted recovery using PyWallet, a command-line wallet recovery tool available on GitHub. The tool returned zero errors and zero wallets found. Shifting strategy, the user conducted hex editor searches for '0201010420', a byte sequence commonly associated with Bitcoin wallet structures, and located over 70 matches. The user extracted 32-byte strings following this marker and converted them to Bitcoin addresses using bitaddress.org in offline mode, testing both compressed and uncompressed formats against the blockchain. All tested addresses showed zero transaction history.
A critical technical problem emerged: the original wallet.dat was encrypted with a passphrase that the user still possessed in written form. Forum respondents HCP and PrimeNumber7 explained that encrypted wallet files do not yield individual private keys to simple hex searches. PyWallet and similar tools require the correct passphrase to decrypt the wallet structure before any key material becomes readable. HCP clarified the technical difference between Windows Quick Format (which resets partition tables but leaves data intact) and full format (which zeros sectors), noting that recovery prospects are high after quick format if sectors remain unoverwritten. PrimeNumber7 recommended using dedicated file recovery software such as Recuva to recover the wallet.dat file itself rather than attempting to extract keys from raw sectors.
When Recuva located .dat files, they were reported as 32 gigabytes in size—implausibly large for a wallet file and likely system files rather than the target. By November 16, 2020, the user indicated plans to import recovered hex strings into Electrum and to conduct an extended full-disk hex scan over several days. No follow-up outcome was documented.
| Stress condition | Device loss |
| Custody system | Software wallet |
| Outcome | Indeterminate |
| Documentation | Partial |
| Year observed | 2020 |
What determines whether device loss is permanent
When a device fails, burns, floods, or disappears, the Bitcoin remains on the blockchain, unchanged. What changes is whether any path to authorized access still exists. A seed phrase stored separately from the device preserves that path. A seed phrase stored with the device — or never recorded at all — eliminates it permanently.
The pattern observed across cases in this archive is consistent: recovery is possible when the seed phrase survived the event that took the device. It is not possible when it did not. The type of device, its cost, its brand, its security features — none of these factors determine the outcome. The seed phrase backup does.
Most device loss cases that result in permanent loss involve one of three failure modes: the seed phrase was never recorded at setup, the seed phrase was stored physically alongside the device and lost with it, or the seed phrase was stored in a location that became inaccessible during the same event (flood, fire, relocation). All three are detectable in advance. A backup test — confirming that the seed phrase can restore the wallet on a separate device — would have revealed the gap before the loss event.
A device loss case becomes unrecoverable the moment the backup path is also broken. The preventive action is simple in concept: record the seed phrase at setup, store it independently from the device, and test that it works. Most cases in this archive involved none of these three steps.
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