Coldman is a tool for a multi-signature, deterministic wallet (BIP 0032) based cold wallet. It bases heavily on pycoin and bitcoind.

Coldman is usable with some manual work to fill the gaps.

Coldtool is a command-line interface.

It's the ultimate solution for a communal cold wallet -- all dressed in tinfoil hattery!

If you can trust your comrades, you just use a shared private key.

First, create a coldman datafile using coldtool data.cm init. You will be asked necessary information about running the cold wallet, including the hot wallet that will be drained.

After the datafile is built, you can add as many BIP 0032 formatted public keys as you like. Bitcoin itself supports up to 20 multisig public keys. Add all keys before making the first transaction: it is not possible to alter the set of public keys after the first transaction is made.

Use coldtool data.cm freeze <amount>. A single-use multisig address is created and the hot wallet is drained immediately.

If you're not expecting to use your coins for a while, you can save the following chapters until then. It's this easy!

First pick which cold wallet address to drain using coldtool data.cm report. Take note of the i value of the address you wish to drain.

Now you can create the unsigned transaction using coldtool data.cm thaw i using the value of i that you picked. By default the transaction will return money to the hot wallet configured for the datafile, but you can specify another address as well.

The printed transaction is not complete, and you need to get it signed with private keys until the multisig requirement is fulfilled.

You can do this step on an offline machine. It is in fact recommended you manage private keys on an offline computer that you communicate transactions to using a thumb drive.

You need to know the raw transaction generated above, the i of the original transaction to spend and the original (deterministic) private key corresponding to a public key added to the datafile. The private key should be in BIP 0032 deterministic key format. Unfortunately the method to get such formatted key from Electrum or other wallets is left as an exercise to the reader.

First derive the zeroth subkey (the default account). Then derive the zeroth subkey from the default account, coming up with the external chain. Finally, you derive the external chain with i. Take note of the resulting private key.

If your wallet software doesn't provide low-level key derivation functions, you can use coldtool data.cm derive wif k to get the kth subkey of the given key. Coldtool doesn't actually need a data file in this case, but it's there for syntax reasons.

Anyway, now that you have the fully derived private key, you can sign it using Bitcoind or Electrum:

bitcoind signrawtransaction <hex part of the raw transaction above> '["<derived private key>"]'

OR

electrum signrawtransaction <hex part of the raw transaction above> '<input_info part of the raw transaction above>' '["<derived private key>"]'

Note that the input_info is a JSON object and the private key is inside a JSON array.

You are returned a new raw transaction at the hex part and indication whether the transaction is sendable in the complete part. If complete is false, repeat this step with different private keys.

On an online Bitcoind or Electrum, use sendrawtransaction:

bitcoind sendrawtransaction <hex part of a complete transaction>

OR

electrum sendrawtransaction <hex part of a complete transaction>

Wait for the transaction to confirm, and enjoy your newly thawed bitcoins.

Please see the Github issue tracker (https://github.com/hylje/coldman/issues)