Quote from: oshirowanen on June 13, 2014, 08:39:06 PM

If my cold wallet (bitcoin-qt) does not have the full block chain, how do I figure out the scriptPubKey?

This seems trivial, just write it down or save it otherwise. If you want to spend outputs of transactions which you create yourself, you already have everything you need: txid, vout#, scripts. The Core client provides the following commands which can be helpful to get the data from raw transactions or (on an online machine) from the blockchain: "decoderawtransaction", "getrawtransaction" or "gettxout". Most block explorers such as blockchain.info display scripts and other stuff, too.

Some general information which may be useful to others who like to sign transactions with an unsynchronized client:

Transaction inputs are references to outputs of other transactions and when you sign a transaction, those references are replaced by the referenced data. An offline client usually has no clue about any transaction and therefore also no idea what you actually like to sign, therefore you need to provide the scriptPubKey(s) explicitly.

I'm going to use bitcoind via command line to demonstrate the whole process. Leave out all "./bitcoind", if you use the -Qt client's debug console which can be opened via "Help" - "Debug window" - "Console".

Say I want to spend some testnet coins associated with n4EmA9R4VmxLnxu9G8yZMDxvBBha8bUtEQ. I need to know which outputs can be spent and to get a list of unspent outputs with at least 1 and at most 9999999 confirmations:

Code:

./bitcoind listunspent 1 9999999 '["n4EmA9R4VmxLnxu9G8yZMDxvBBha8bUtEQ"']

[{
  "txid": "77d35b87d1ad549011b66dbb06ec7b6d84b06325ee9c18cf6f3467e9b7a7bda2",
  "vout": 0,
  "address": "n4EmA9R4VmxLnxu9G8yZMDxvBBha8bUtEQ",
  "account": "",
  "scriptPubKey": "76a914f93af105187d21ed6adfa5d71bfada7d7324e53c88ac",
  "amount": 1.90978096,
  "confirmations": 233
}]

Txid and vout are used to create a raw transaction:

Code:

./bitcoind createrawtransaction '[{"txid" : "77d35b87d1ad549011b66dbb06ec7b6d84b06325ee9c18cf6f3467e9b7a7bda2","vout":0}]' '{"n4EmA9R4VmxLnxu9G8yZMDxvBBha8bUtEQ":1.90968096}'

0100000001a2bda7b7e967346fcf189cee2563b0846d7bec06bb6db6119054add1875bd3770000000000ffffffff0120f1610b000000001976a914f93af105187d21ed6adfa5d71bfada7d7324e53c88ac00000000

Some details about this unsigned transaction:

Code:

./bitcoind decoderawtransaction 0100000001a2bda7b7e967346fcf189cee2563b0846d7bec06bb6db6119054add1875bd3770000000000ffffffff0120f1610b000000001976a914f93af105187d21ed6adfa5d71bfada7d7324e53c88ac00000000

{
  "txid": "e8ecde1d813f320a96ed34f7791e9f62fc86070d5d96b881397285ddbebd7fff",
  "version": 1,
  "locktime": 0,
  "vin": [{
   "txid": "77d35b87d1ad549011b66dbb06ec7b6d84b06325ee9c18cf6f3467e9b7a7bda2",
   "vout": 0,
   "scriptSig": {
   "asm": "",
   "hex": ""
   },
   "sequence": 4294967295
  }],
  "vout": [{
   "value": 1.90968096,
   "n": 0,
   "scriptPubKey": {
   "asm": "OP_DUP OP_HASH160 f93af105187d21ed6adfa5d71bfada7d7324e53c OP_EQUALVERIFY OP_CHECKSIG",
   "hex": "76a914f93af105187d21ed6adfa5d71bfada7d7324e53c88ac",
   "reqSigs": 1,
   "type": "pubkeyhash",
   "addresses": [
   "n4EmA9R4VmxLnxu9G8yZMDxvBBha8bUtEQ"
   ]
   }
  }]
}

What's important is the scriptPubKey of the output that I try to spend. This is "76a914f93af105187d21ed6adfa5d71bfada7d7324e53c88ac" in this case. The hex of the raw transaction, txid and vout# of the output to spent as well as the private key to sign the transaction are also required.

This data is used on an offline machine to sign the transaction:

Code:

./bitcoind signrawtransaction 0100000001a2bda7b7e967346fcf189cee2563b0846d7bec06bb6db6119054add1875bd3770000000000ffffffff0120f1610b000000001976a914f93af105187d21ed6adfa5d71bfada7d7324e53c88ac00000000 '[{"txid":"77d35b87d1ad549011b66dbb06ec7b6d84b06325ee9c18cf6f3467e9b7a7bda2","vout":0,"scriptPubKey":"76a914f93af105187d21ed6adfa5d71bfada7d7324e53c88ac"}]' '["cSf2Lcme2kSpkZ1s5AW8a2K2Y41P8HYGoXAevNzPUna6iXDw9boC"]'

{
"hex": "0100000001a2bda7b7e967346fcf189cee2563b0846d7bec06bb6db6119054add1875bd377000000006a4730440220528e92bc890b362efcab0ab1af0f9427d501909be59fe22dbdb4c26eac17418102206eb9c83360ad46c9f17be32ea15a08d2765a934e08ce6f2578b3379bbfa03afd0121024451fc7d9e271fab77265bd0292fc274ee231e7ecc076bf6269999c0cbbf9f90ffffffff0120f1610b000000001976a914f93af105187d21ed6adfa5d71bfada7d7324e53c88ac00000000",
"complete": true
}

Back on my online machine I broadcast the signed transaction:

Code:

./bitcoind sendrawtransaction 0100000001a2bda7b7e967346fcf189cee2563b0846d7bec06bb6db6119054add1875bd377000000006a4730440220528e92bc890b362efcab0ab1af0f9427d501909be59fe22dbdb4c26eac17418102206eb9c83360ad46c9f17be32ea15a08d2765a934e08ce6f2578b3379bbfa03afd0121024451fc7d9e271fab77265bd0292fc274ee231e7ecc076bf6269999c0cbbf9f90ffffffff0120f1610b000000001976a914f93af105187d21ed6adfa5d71bfada7d7324e53c88ac00000000

d1432ed0ea9409bea9bf4aaea8752d76a8708b3f6c10231879b4871e423cac92

... and fetch it once more, just for the sake of getting some data which includes the scriptPubKey:

Code:

./bitcoind getrawtransaction d1432ed0ea9409bea9bf4aaea8752d76a8708b3f6c10231879b4871e423cac92 1

{
  "hex": "0100000001a2bda7b7e967346fcf189cee2563b0846d7bec06bb6db6119054add1875bd377000000006a4730440220528e92bc890b362efcab0ab1af0f9427d501909be59fe22dbdb4c26eac17418102206eb9c83360ad46c9f17be32ea15a08d2765a934e08ce6f2578b3379bbfa03afd0121024451fc7d9e271fab77265bd0292fc274ee231e7ecc076bf6269999c0cbbf9f90ffffffff0120f1610b000000001976a914f93af105187d21ed6adfa5d71bfada7d7324e53c88ac00000000",
  "txid": "d1432ed0ea9409bea9bf4aaea8752d76a8708b3f6c10231879b4871e423cac92",
  "version": 1,
  "locktime": 0,
  "vin": [{
   "txid": "77d35b87d1ad549011b66dbb06ec7b6d84b06325ee9c18cf6f3467e9b7a7bda2",
   "vout": 0,
   "scriptSig": {
   "asm": "30440220528e92bc890b362efcab0ab1af0f9427d501909be59fe22dbdb4c26eac17418102206eb9c83360ad46c9f17be32ea15a08d2765a934e08ce6f2578b3379bbfa03afd01 024451fc7d9e271fab77265bd0292fc274ee231e7ecc076bf6269999c0cbbf9f90",
   "hex": "4730440220528e92bc890b362efcab0ab1af0f9427d501909be59fe22dbdb4c26eac17418102206eb9c83360ad46c9f17be32ea15a08d2765a934e08ce6f2578b3379bbfa03afd0121024451fc7d9e271fab77265bd0292fc274ee231e7ecc076bf6269999c0cbbf9f90"
   },
   "sequence": 4294967295
  }],
  "vout": [{
   "value": 1.90968096,
   "n": 0,
   "scriptPubKey": {
   "asm": "OP_DUP OP_HASH160 f93af105187d21ed6adfa5d71bfada7d7324e53c OP_EQUALVERIFY OP_CHECKSIG",
   "hex": "76a914f93af105187d21ed6adfa5d71bfada7d7324e53c88ac",
   "reqSigs": 1,
   "type": "pubkeyhash",
   "addresses": [
   "n4EmA9R4VmxLnxu9G8yZMDxvBBha8bUtEQ"
   ]
   }
  }]
}

To get information of the (unspent) output of this new transaction:

Code:

./bitcoind gettxout d1432ed0ea9409bea9bf4aaea8752d76a8708b3f6c10231879b4871e423cac92 0

{
  "bestblock": "0000000039ba07b3b39ef2c7b31a9942fb1d44528cf654e1ea956a9fdbc191b6",
  "confirmations": 0,
  "value": 1.90968096,
  "scriptPubKey": {
   "asm": "OP_DUP OP_HASH160 f93af105187d21ed6adfa5d71bfada7d7324e53c OP_EQUALVERIFY OP_CHECKSIG",
   "hex": "76a914f93af105187d21ed6adfa5d71bfada7d7324e53c88ac",
   "reqSigs": 1,
   "type": "pubkeyhash",
   "addresses": [
   "n4EmA9R4VmxLnxu9G8yZMDxvBBha8bUtEQ"
   ]
  },
  "version": 1,
  "coinbase": false
}