Quote from: CryptoPadawan on July 17, 2019, 08:21:46 AM

So if there are three private keys controlled by my xprv. And when I spend all my unspent outputs (all my BTC on HW wallet) in one transaction, it actually using three private keys for signing? So it's actually three transactions?

No, it's one transaction spending 3 unspent outputs that were funding 3 addresses. Your wallet will use 3 private keys to sign this one transaction.

I'll try to give an example... This is the last transaction i made (publicly):
https://www.blockchain.com/btc/tx/aa4e570adc48116013f0b562bc9fd8a1d45a0608799ab9f82881c6fd897fe772

Click on "Show scripts & coinbase"

You'll see i'm spending 3 unspent outputs (in this case, funding the same address), you'll also see 3 ScriptSig scripts... If i was spending unspent outputs funding different addresses, those signatures at the bottom would be made with 3 private keys instead of one, that's all...

Actually, here's the decoded raw transaction:

Code:

bitcoin@node:~$ bitcoin-cli getrawtransaction aa4e570adc48116013f0b562bc9fd8a1d45a0608799ab9f82881c6fd897fe772
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
bitcoin@node:~$ bitcoin-cli decoderawtransaction 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
{
  "txid": "aa4e570adc48116013f0b562bc9fd8a1d45a0608799ab9f82881c6fd897fe772",
  "hash": "aa4e570adc48116013f0b562bc9fd8a1d45a0608799ab9f82881c6fd897fe772",
  "version": 2,
  "size": 616,
  "vsize": 616,
  "locktime": 578637,
  "vin": [
   {
   "txid": "2c2aeff0cabafbe2bc0cfb1d5fa20c0eb87e902377122e93a4f1695a8a570a70",
   "vout": 0,
   "scriptSig": {
   "asm": "30450221008c85fe94c4fcc32fc948733db3de1ba597f7c7c7cebfa21582d96292f57d4d2e02207a864ec1e305eede42b72d3a80e0989c424555714e8faa0e6766e9be6a00b28b[ALL] 04ed1df4aaa790f8118646976365a33de02dcbb4c78d92edf1271a85abe53c15a316d08c29b1069a52ae98e015a29aa52cbeb41c1fb77bf091d809d286adff8a73",
   "hex": "4830450221008c85fe94c4fcc32fc948733db3de1ba597f7c7c7cebfa21582d96292f57d4d2e02207a864ec1e305eede42b72d3a80e0989c424555714e8faa0e6766e9be6a00b28b014104ed1df4aaa790f8118646976365a33de02dcbb4c78d92edf1271a85abe53c15a316d08c29b1069a52ae98e015a29aa52cbeb41c1fb77bf091d809d286adff8a73"
   },
   "sequence": 4294967293
   },
   {
   "txid": "77b919a14cfa923ad4daab98ca0f3d8f8623e8cfd533028445613b4157cbd583",
   "vout": 421,
   "scriptSig": {
   "asm": "3045022100f3c25ac424dfff0fa1fae176450f7b666200657468de1e0eae20e3c003d5db050220782ccdb95f53acf7dede4d8456272e1d10ed0d8d7da02d08c1ed82b56aedf052[ALL] 04ed1df4aaa790f8118646976365a33de02dcbb4c78d92edf1271a85abe53c15a316d08c29b1069a52ae98e015a29aa52cbeb41c1fb77bf091d809d286adff8a73",
   "hex": "483045022100f3c25ac424dfff0fa1fae176450f7b666200657468de1e0eae20e3c003d5db050220782ccdb95f53acf7dede4d8456272e1d10ed0d8d7da02d08c1ed82b56aedf052014104ed1df4aaa790f8118646976365a33de02dcbb4c78d92edf1271a85abe53c15a316d08c29b1069a52ae98e015a29aa52cbeb41c1fb77bf091d809d286adff8a73"
   },
   "sequence": 4294967293
   },
   {
   "txid": "a304624a432de61610efb6cff33fb3de34f9f0616c7c73c399b3270aec2cc837",
   "vout": 0,
   "scriptSig": {
   "asm": "3045022100a6cadc449c1ed0a683971f6e7b74d278014b19a424f2c30de830afd4ba586a5d02207830a1fddb67bf0f2bdc1c455313d9296c6b774d4010ef98b216931451a58bfb[ALL] 04ed1df4aaa790f8118646976365a33de02dcbb4c78d92edf1271a85abe53c15a316d08c29b1069a52ae98e015a29aa52cbeb41c1fb77bf091d809d286adff8a73",
   "hex": "483045022100a6cadc449c1ed0a683971f6e7b74d278014b19a424f2c30de830afd4ba586a5d02207830a1fddb67bf0f2bdc1c455313d9296c6b774d4010ef98b216931451a58bfb014104ed1df4aaa790f8118646976365a33de02dcbb4c78d92edf1271a85abe53c15a316d08c29b1069a52ae98e015a29aa52cbeb41c1fb77bf091d809d286adff8a73"
   },
   "sequence": 4294967293
   }
  ],
  "vout": [
   {
   "value": 0.00150000,
   "n": 0,
   "scriptPubKey": {
   "asm": "OP_HASH160 6455b6f90b32cd4b824f1ca0cb1f6ca85c41e28c OP_EQUAL",
   "hex": "a9146455b6f90b32cd4b824f1ca0cb1f6ca85c41e28c87",
   "reqSigs": 1,
   "type": "scripthash",
   "addresses": [
   "3AqYBHqkwhKHLo2wCJ8bh8dvs6dmEFWVnV"
   ]
   }
   },
   {
   "value": 0.01289663,
   "n": 1,
   "scriptPubKey": {
   "asm": "OP_DUP OP_HASH160 e432ffb6ef0bde696af29ca13dd37c0824a40823 OP_EQUALVERIFY OP_CHECKSIG",
   "hex": "76a914e432ffb6ef0bde696af29ca13dd37c0824a4082388ac",
   "reqSigs": 1,
   "type": "pubkeyhash",
   "addresses": [
   "1MocACiWLM8bYn8pCrYjy6uHq4U3CkxLaa"
   ]
   }
   }
  ]
}