02-wallet.md

02 Wallet

Example: Buy bitcoins

• get new address and print QR code

ADDR=`bc getnewaddress`
qrencode -m 1 -t ansi256 bitcoin:$ADDR

• check if coins are received

bc getreceivedbyaddress $ADDR 0
bc getreceivedbyaddress $ADDR 1

• polling is not the smartest way to do this
  • bd ... -walletnotify='echo %s >> ~/wallet.txt'
  • bd ... -zmqpubrawblock=<zmq socket address>

Example: Sell bitcoins

bc sendtoaddress <address> <amount>

Transaction info

• bc listtransactions
• bc gettransaction <txid> | egrep "confirmation|fee"
• list your addresses
  • bc getaddressesbyaccount ""

Backup

• ~/.bitcoin/wallet.dat contains
  • master seed
  • addr and tx metadata
• backup: turn off bitcoind and copy wallet.dat
• restore: copy saved wallet.dat back
  • start with bd ... -rescan
  • bc getnewaddress
• encryption
  • either bc encryptwallet
    • metadata not encrypted
  • or manual

Offline signing

• means that signing key is not on machine connected to the internet
• with Bitcoin Core
  • https://people.xiph.org/~greg/signdemo.txt
  • https://github.com/rustyrussell/bitcoin-storage-guide
• or hardware wallets
  • ledger
  • trezor
  • digital bitbox

Transactions

• bc getrawtransaction

  • requires bd ... -txindex
  • bc getrawtransaction f4184fc596403b9d638783cf57adfe4c75c605f6356fbc91338530e9831e9e16 1
  • can't look up "addresses", as there is no index for it

• an exemplary transaction subgraph

  +------------+
  |       out0 +---+
  +------------+   |    +------------+
  TxA              +----> in0   out0 |
                        |            |
                   +----> in1        |
  +------------+   |    +------------+
  |       out0 +---+    TxC
  |            |
  |       out1 |
  +------------+
  TxB
  

"Raw" transaction interface

• useful for

  • spending multisig
    • multisig: f.e. need 2 of 3 keys to spend
    • creating bc createmultisig 1 '["$PK1", "$PK2"]'
  • offline signing
  • control over which exact coins to spend

• bc listunspent

• bc createrawtransaction

  • don't forget to add change!

• bc signrawtransaction

• bc submitrawtransaction

• even more control with the bitcoin-tx tool

Create m-of-n multisig

• bc getnewaddress
• find pubkey with bc validateaddress <address> and broadcast to signers
• all signers: bc addmultisigaddress m '["pubKey_1", ..., "pubKey_n"]'

Spend m-of-n multisig

• bc createrawtransaction '[{"txid": "multisig_output_txid", "vout": vout, "nValue": value}]' '{"destination_address": value}'
• bc signrawtransaction <txhex>
• pass signature to next signer until complete
• bc sendrawtransaction <signed_txhex>