Background
The client — an early Bitcoin adopter in their 50s — had purchased Bitcoin between 2017 and 2019 and stored it on a Trezor Model T hardware wallet. The device was kept in a home office that sustained water damage from a burst pipe. The Trezor device was rendered non-functional and the paper seed phrase backup, stored in the same room, had six words that were illegible due to water damage. The client contacted us four weeks after the incident.
The Recovery Challenge
The Trezor Model T stores private keys in a microcontroller secured against direct extraction — the device itself could not be simply read. With the device non-functional, the only recovery path was through the seed phrase.
Of the 24 BIP-39 seed words, 18 were fully legible. The remaining six ranged from partially legible (three words had some letters visible) to completely illegible (three words were entirely water-damaged). The position of each missing word within the 24-word sequence was known from the backup format.
BIP-39 seed phrases use a dictionary of exactly 2,048 words. With 18 known words, three partial words, and three unknown words, the recovery required systematic testing of valid word combinations while verifying against the known Bitcoin wallet address on the blockchain.
Our Approach
We catalogued all 24 word positions, documented the legible letters from the three partially damaged words, and established the constraint set for the unknown words.
Using the partial letter information, we narrowed the candidate list for the three partially legible words from 2,048 each to between 8 and 34 candidates per position.
We derived the client's known Bitcoin address from the seed phrase structure, which allowed us to verify candidate combinations against the blockchain without needing to access the funds.
Our recovery tools tested valid BIP-39 word combinations systematically, verifying each candidate against the known address. The correct combination was identified within the first 48 hours of active testing.
Once the full seed phrase was reconstructed, we guided the client through restoring access on a new hardware wallet and verified the full balance was accessible before concluding the engagement.
Challenges We Overcame
- Three completely unknown word positions required testing from the full BIP-39 dictionary of 2,048 words each — a computationally intensive task requiring optimised tooling.
- BIP-39 seed phrases include a built-in checksum that eliminated invalid combinations — this reduced the search space significantly but still required substantial processing time.
- The client's backup used non-standard word spacing that initially caused uncertainty about the position of some words — careful document analysis resolved this before recovery began.
- A secondary verification step was required after the initial reconstruction identified two plausible candidate phrases — further blockchain analysis confirmed the correct one.
Outcome
Final Outcome
Full access to the client's $203,000 in Bitcoin was restored 11 days after the case opened. The complete 24-word seed phrase was reconstructed and the client set up a new hardware wallet with a secure backup procedure. The Bitcoin was confirmed accessible and unaffected — it had never moved from the original addresses during the period of inaccessibility.
I had written off losing that Bitcoin. When they called to say they had found the full seed phrase I genuinely did not believe it at first. Eleven days to get back access to a decade of savings — remarkable.
Client, Australia (name withheld)
Key Lessons
- Seed phrase backups should be stored in multiple secure locations — at minimum one off-site and one resistant to water and fire damage (steel backup plates are a practical solution).
- Even with six of 24 words missing, recovery was possible because the known address provided a verification target — keeping a record of at least one wallet address alongside the backup significantly aids recovery.
- The BIP-39 checksum eliminates the vast majority of invalid combinations, making partial seed phrase recovery computationally feasible in many cases.
- Acting quickly after a hardware failure is important — had the client waited longer and some of the partial words had further degraded, the recovery would have become significantly harder.