Tracking and spending ordinary Bitcoin addresses

Tracking and spending ordinary Bitcoin (non-MMGen) addresses

While not recommended, it is possible to use MMGen to track and spend ordinary Bitcoin addresses too, i.e. addresses whose keys you control but which haven’t been spent to your MMGen wallet.

Import the Bitcoin addresses for tracking (online computer):

Make a plain list of the addresses, one address per line, and import the list into the tracking wallet:

$ mmgen-addrimport --rescan -l my_existing_addrs

NOTE: The '--rescan' option forces a rescan of the entire block chain, which is required for all addresses with existing balances. The rescanning process is very slow, and Bitcoin Core unfortunately doesn’t support rescanning in batch mode. This is why you should always import new addresses into the tracking wallet before spending into them, whenever possible.

Create a keylist file for signing transactions (online computer):

To sign transactions that spend from the Bitcoin addresses you’ve imported, you need their corresponding private keys.

If the key or keys in question are in a bitcoind wallet ('wallet.dat'), you can extract them to a keylist file using the 'bitcoin-cli dumpwallet' command:

$ bitcoin-cli dumpwallet my_secret.keys

This will write the keylist file 'my_secret.keys' to your home directory (or maybe to your Bitcoin data directory, results may vary). If you want it written to another location, provide an absolute path.

Note that the keylist file lists your private keys in unencrypted form. Therefore, it should be backed up to a safe location—to a USB stick, say, or your offline computer. After backing up, securely delete all copies of the list on your online computer using a utility such as 'wipe'.

You may also create your own 'my_secret.keys' (or whatever you choose to call it) file in a plain text editor. In it, just list the WIF-format keys corresponding to the addresses you’ve imported, one key per line.

Sign a transaction using the keylist (offline computer):

After creating a transaction that spends from one of your ordinary Bitcoin addresses, transfer the raw transaction file to your offline computer and sign it with the keylist file:

$ mmgen-txsign -k my_secret.keys F9DCBA[6.6].rawtx
...
Signed transaction written to file 'F9DCBA[6.6].sigtx'

If your transaction also contains MMGen inputs, you’ll need to provide a wallet for them too, listing it at the end of the command line, like this:

$ mmgen-txsign -k my_secret.keys F9DCBA[6.6].rawtx 89ABCDEF-76543210[256,3].mmdat

That’s it! Your signed transaction is ready to broadcast.