Recovering Bitcoin from after the gap limit

[Br3nt0n]

I run a website and have received payments to an xpub BTC address for months. Someone decided it'd be funny to spam create invoices, which generated over 50,000 unused bitcoin addresses through the xpub key. I received a few payments after this on the same xpub key, which I can't access because the gap limit is over 50,000.


I have the gap indexes and the addresses that contain a balance, but I don't know how I'd send the Bitcoin from these addresses because no wallet allows a gap limit so high. I use the Electrum wallet.


Any ideas on how I can recover the BTC in these 3 addresses?

[LoyceV]

Any ideas on how I can recover the BTC in these 3 addresses?

I think you can use IanColeman's Mnemonic Code for this. You can set "start from index" to 50,000.
Note that you should do this offline, preferrably running from an air-gapped Live Linux DVD so you can wipe it's memory by turning it off when you're done.

Update: After some quick testing, I'm not so sure how to enter an Electrum seed into IanColeman's code.

[Lucius]

Update: After some quick testing, I'm not so sure how to enter an Electrum seed into IanColeman's code.

Some modifications are needed to make Electrum seed functional in the Ian Coleman tool - at least that's explained in this thread, in case I didn't misunderstand something.

https://bitcointalk.org/index.php?topic=4595261.msg41815678#msg41815678

The iancoleman code has been updated since those changes were suggested by HCP, so although those are still the changes you need to make, you will no longer find that code at the same places.

Download the repository from here: https://github.com/iancoleman/bip39
Navigate to the folder BIP39/src/js
Open the file jsbip39.js
The string return h == nh; is at line 116, and the string passphrase = "mnemonic" + passphrase; is at line 144.

The other instructions OP has given are correct. Make these code changes and repeat those steps, and you will be able to replicate your Electrum addresses.

Of course with all those settings that are in the OP - > https://bitcointalk.org/index.php?topic=5257708.msg54681093#msg54681093

[o_e_l_e_o]

Since my post above, the relevant code is now on line 118 and 146. These changes essentially stop Ian Coleman from returning an invalid checksum error (since Electrum seed phrases don't use a checksum), and change the salt from BIP39's "mnemonic" to Electrum's "electrum".

So yes, download and verify Ian Coleman, transfer to an airgapped computer, make the necessary changes as above, enter your seed phrase, choose BIP 44/49/84 as needed, change the index as needed, grab the individual private keys and import them back in to a fresh Electrum wallet.

Alternatively of course you could just pull your master private key from your Electrum wallet and put that in to an unmodified Ian Coleman and derive from there. Select BIP32 at m/0 for legacy or BIP141 with P2WPKH at m/0'/0 for segwit.

[Br3nt0n]

Thanks a lot <3

Did all that and used Electrum's sweep tool to send the BTC to my new address.

Thanks again