Merge #413: step-by-step guide on how to use HWI and Bitcoin Core

7de0237 detailed walk-through of using Bitcoin Core with a hardware wallet (8go)

Pull request description:

  This page shows in details through screenshots and description on how to use a hardware wallet with Bitcoin Core through the help of HWI. I hope this one-pager helps people to see how it works, takes their fear and increments the use of hardware wallets with Bitcoin Core.

ACKs for top commit:
  achow101:
    ACK 7de0237

Tree-SHA512: b8ad8462c6121261b484323316fd9cb44e3a1cf584a96df42a5833e48f60962305c3a99096a948e1aa59b4fbeade3c780b1b699e4260813597ab3b4a3a88cf07

docs/walk-through/README.rst

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+How to Use a Hardware Wallet with Bitcoin Core Wallet
+*****************************************************
+
+A Step-by-step Walk-Through
+***************************
+
+Summary: On this page we describe step-by-step and show in screenshots how to use a hardware wallet and HWI 
+together with a Bitcoin Core Wallet. As hardware wallet example we have used a Trezor.
+
+Create a watch-only Bitcoin Core wallet for Trezor
+==================================================
+
+Create your watch-only Bitcoin Core Wallet as described in `Using Bitcoin Core with Hardware Wallets <../bitcoin-core-usage.rst>`_. 
+You find all the details well described in this link. But in summary, one opens a terminal and runs ``bitcoind``. E.g.
+
+::
+
+  bitcoind -testnet  -datadir=$HOME/.bitcoin-testnet
+
+for a testnet ``bitcoind`` daemon, or
+
+::
+
+  bitcoind
+
+for a mainnet, i.e. regular, ``bitcoind`` daemon.
+
+Then in another terminal run commands similar to these, adapted to your environment:
+
+::
+
+  hwi.py enumerate # this shows you the fingerprint of your hardware wallet
+  FINGERPRINT_TESTNET="yourHardwareWalletFingerprint" # shown by "hwi enumerate"
+  # in this example we use SEGWIT BECH32 ADDRESSES
+  DERIVATIONPATH_TESTNET=1 # testnet uses derivation paths like m/84h/1h/0h/0/* and m/84h/1h/0h/1/*
+  DERIVATIONPATH_MAINNET=0 # mainnet uses derivation paths like m/84h/0h/0h/0/* and m/84h/0h/0h/1/*
+  # if the mainnet path is used on testnet, it will work too, but Trezor device gives warnings 
+  # of unknown address on Trezor display. This is not recommended. Use the correct derivation path
+  # for the corresponding network!
+  wallet=wallet.test
+  rec=$(hwi --testnet -f $FINGERPRINT_TESTNET getkeypool --addr-type wpkh --path m/84h/${DERIVATIONPATH_TESTNET}h/0h/0/* --keypool 0 1000)
+  chg=$(hwi --testnet -f $FINGERPRINT_TESTNET getkeypool --addr-type wpkh --path m/84h/${DERIVATIONPATH_TESTNET}h/0h/1/* --keypool --internal 0 1000)
+  bitcoin-cli -testnet createwallet "$wallet" true
+  bitcoin-cli -testnet -rpcwallet="$wallet" importmulti "$rec"
+  bitcoin-cli -testnet -rpcwallet="$wallet" importmulti "$chg"
+  echo "If the hardware wallet has been used before and holds funds then you should rescan. Rescanning might take 30 minutes."
+  bitcoin-cli -testnet -rpcwallet="$wallet" rescanblockchain # full rescan
+  # after rescan unload wallet
+  bitcoin-cli -testnet -rpcwallet="$wallet" unloadwallet
+
+This script needs to be adapted to your needs. If you are creating a wallet for mainnet get rid of ``-testnet`` and ``--testnet`` and 
+use ``DERIVATIONPATH_MAINNET`` instead of ``DERIVATIONPATH_TESTNET``. Adapt the derivation paths to your needs. 
+Now that the watch-only Bitcoin Core wallet has been created, stop ``bitcoind`` with control-C. We are ready to use the wallet.
+
+Send funds with Bitcoin Core and Trezor using HWI
+=================================================
+
+* our example does everything on the Bitcoin testnet, so watch out, your addresses and paths will differ
+* TREZOR: plug in your hardware wallet, e.g. your Trezor, put in the PIN if any
+* HWI: type ``hwi-qt.py --testnet`` to start HWI GUI for testnet (type ``hwi-qt.py`` to start HWI GUI for mainnet)
+
+.. image:: Screenshot01_HWI_Empty-State.png
+
+* TREZOR: your hardware wallet, e.g. Trezor, might prompt you for a passphrase, enter passphrase on hardware wallet (if any)
+* HWI: select your hardware wallet in HWI GUI
+
+.. image:: Screenshot02_HWI_HWW-Selected.png
+
+* CORE: start Bitcoin Core wallet, e.g. ``bitcoin-qt -testnet`` (or ``bitcoin-qt`` for mainnet)
+
+.. image:: Screenshot03-Core-Initial-Wallet-Overview.png
+
+* on the very first run it might be a good idea to verify that the wallet has been created correctly
+* on first run **verify your wallet** (optional)
+* HWI: HWI GUI -> "Display Address", since we use BECH32 address, select "P2WPKH", 
+  enter "m/84h/1h/0h/0/0" (testnet derivation path) (or "m/84h/0h/0h/0/0" on mainnet). 
+  This path represents the first receiving address. Click "Go". 
+  In our example, it shows address "tb1q0r2gn9wzfjm5j5zshx5yp5342h928c8pmllfep".
+
+.. image:: Screenshot04_HWI_Address-Display-Request.png
+
+.. image:: Screenshot05_HWW_Display-Receive-Address.png
+
+.. image:: Screenshot06_HWI_Address-Display-Response.png
+
+* CORE: In Core Wallet, open "Console", enter ``getaddressinfo tb1q0r2gn9wzfjm5j5zshx5yp5342h928c8pmllfep``, 
+  observe these values:
+  It is crucial that ``solvable`` shows as ``true``!
+
+  * "solvable": true,
+  * "iswatchonly": true,
+  * "hdkeypath": "m/84'/1'/0'/0/0",
+
+.. image:: Screenshot07_Core_Console-getaddressinfo.png
+
+* HWI: In HWI GUI main window click "Display Address", since we use BECH32 address, 
+  select "P2WPKH", enter "m/84h/1h/0h/1/0" (testnet derivation path) (or "m/84h/0h/0h/1/0" on mainnet).
+  This path represents the first change address. Click "Go". 
+  In our example it shows address "tb1qca3u0ka22c934jfqw7gjr9vg4gwwjldpzatrh5".
+
+.. image:: Screenshot08_HWI_Address-Display-Request.png
+
+.. image:: Screenshot09_HWW_Display-Change-Address.png
+
+.. image:: Screenshot10_HWI_Address-Display-Response.png
+
+* CORE: In Core Wallet, open "Console", enter ``getaddressinfo tb1qca3u0ka22c934jfqw7gjr9vg4gwwjldpzatrh5``, 
+  observe these values: 
+  It is crucial that ``solvable`` shows as ``true``!
+
+  * "solvable": true,
+  * "iswatchonly": true,
+  * "hdkeypath": "m/84'/1'/0'/1/0",
+
+.. image:: Screenshot11_Core_Console-getaddressinfo.png
+
+* If you see the same addresses for the same paths on Trezor, in HWI and in Bitcoin Core Wallet 
+  you can rest assured that the wallet has been created correctly and 
+  that the Bitcoin Core wallet corresponds to your Trezor device.
+
+* Now let us **send funds**.
+
+* CORE: To send funds, open the "Send" tab in Bitcoin Core Wallet, 
+  then select input, amount, fees, etc. Once satisifed, click "Create Unsigned", 
+  verify any displayed information, then click "Create Unsigned" again.
+  The PSBT (Partially Signed Bitcoin Transaction) is now on the clipboard.
+
+.. image:: Screenshot12_Core_Send-Tab.png
+
+.. image:: Screenshot13_Core_Create-Unsigned-Tx.png
+
+.. image:: Screenshot14_Core_Paste-PSBT-to-Clipboard.png
+
+* HWI: In HWI GUI main window click "Sign PSBT", then paste PSBT from clipboard 
+  into the above text field. After paste, click "Sign PSBT".
+
+.. image:: Screenshot15_HWI_Empty-PSBT.png
+
+.. image:: Screenshot16_HWI_Prepare-PSBT-signing.png
+
+* TREZOR: verify signing on Trezor, accept operation on Trezor if all is correct
+
+.. image:: Screenshot17_HWW_Confirm-Amount-Destination.png
+
+.. image:: Screenshot18_HWW_Confirm-Locktime.png
+
+.. image:: Screenshot19_HWW_Confirm-Amount-Fees.png
+
+* CORE: Trezor prints blockheight of locktime which can optionally be verified in 
+  Bitcoin Core Wallet (Console -> ``getblockcount``). For a simple send the locktime
+  is now and you should get the current blockheight.
+
+.. image:: Screenshot20_Core_Console_getblockcount.png
+
+* HWI: upon accepting on Trezor, the HWI bottom text area is filled. 
+  Select the bottom output, and copy full output from the bottom text area to the clipboard
+
+.. image:: Screenshot21_HWI_Show-Signed-PSBT.png
+
+* CORE: In Bitcoin Core Wallet, go to the pull-down menu: select File -> Load from Clipboard.
+
+.. image:: Screenshot22_Core_Broadcast-Signed-PSBT.png
+
+* CORE: In Core Wallet, visually verify again, then click "Broadcast Tx" button. 
+  Once broadcasted, click "Close".
+  The funds have been sent to the mempool awaiting confirmations on the Bitcoin network.
+
+* CORE: In Core Wallet, go to "Transactions" tab. Here you can find the just 
+  sent transaction in the top line. Wait for confirmations. 
+
+.. image:: Screenshot23_Core_Transactions-Tab.png
+
+* CORE: Optionally double click transaction to see transaction details.
+
+.. image:: Screenshot24_Core_Transaction-Details.png
+
+* CORE: Optionally, one can also see the transaction details in the 
+  Console -> ``gettransaction 58d9dccd190250742c47733f3c0f0d33075d65621196434f163f92b69847843f``
+
+.. image:: Screenshot25_Core_Console-gettransaction.png
+
+* HWI: close HWI GUI
+* CORE: close Core wallet
+* you are done! Pad yourself on the shoulder ;)
+
+Versions Used
+=============
+
+* This walk-trough was done in Janary 2021
+* HWI version 1.2.1
+* Bitcoin 0.21.0