Alistair Mann - 16 Sep 2019

Overview

This project was to learn more about how raw transactions can be signed, and develops runeks' answer at https://bitcoin.stackexchange.com/a/5241/89798. Please note ONLY presegwit transactions (version 01000000) are supported.

I expand on the original snippet to include generating the transactions used and change the output to assist single-stepping through the resulting signed transaction.

Linux, bash and python2 are assumed.

Note: This project was developed on a 2016-era Linux Mint 17.3 system downloaded from https://linuxmint.com/edition.php?id=204. I'm aware that the file brutus/ecdsa_ssl.py contains the line priv_key = ssl.BN_bin2bn(secret, 32, ssl.BN_new()) which segfaults on Debian 9 (2017) and Kubuntu 18.04 (2018).

Usage

To run with just the example regtest data: python2 scripts/bsec-3374.py

To generate fresh data:

1. Install bitcoin-0.13.2
2. Add the provided config/regtest.conf file to your .bitcoin directory
3. Install bitcoin-tool (by Mat Anger)
4. Run scripts/generate-new-tx.sh
5. Edit the four displayed variables into scripts/bsec-3374.py
6. Run python2 scripts/bsec-3374.py

Optionally, to see your transaction single-stepped:

1. Install btcdeb
2. take the output from bsec-3374.py above and run as a command. See btcdeb/README.md for more details.

Repository contents

bitcoin-0.13.2/

The code as originally written relied on uncompressed public keys being used in constructing the transaction. As these required using a version earlier than 0.6.0 - which seems pretty hard to find - I adjusted the code to use the compressed public keys of later versions.

Also as the code stands segwit transactions cannot be signed. They became the default with version 0.14.0.

I use version 0.13.2 to meet the above constraints, downloading it from: https://bitcoin.org/bin/bitcoin-core-0.13.2/bitcoin-0.13.2.tar.gz and provided here. Its SHA256 is 621201189c0409cb17a5073278872dcdcfff1ea147ead6958b55e94416b896d7

config/regtest.conf

This project generates example presegwit transactions intended for the regtest network. This is the config file used.

bitcointools/

https://github.com/runeksvendsen/bitcointools as at 26 Sep 2012. Runes K. Svendsen's tools, used for for serializing and deserializing transactions, and base58 encoding/decoding. This is the nearest equivalent I can find to Gavin Andresen's now defunct repository which was used in the original answer.

brutus/

https://github.com/runeksvendsen/brutus/ as at 30 Oct 2012. Runes K. Svendsen's fork of ecdsa_ssl.py from Joric's Brutus repository. Used for constructing public/private EC key pairs and ECDSA signing.

bitcoin-tool/

https://github.com/matja/bitcoin-tool as at 3 Mar 2018. Mat Anger's tool, used to convert the compressed private keys to hex.

scripts/

scripts/generation-new-tx.sh

This script will reset regtest, then construct a single transaction on your new regtest network. It will then display four variables: HEX_TRANSACTION, OUTPUT_INDEX, SEND_TO_ADDRESS and PRIVATE_KEY.

This will give you insight into where ThePiachu's data came from.

scripts/bsec-3374.py

This is an adaptation of runeks' script.

This script comes preloaded with regtest example data, not the mainnet example data from ThePiachu's question. The original merely printed out the raw, signed transaction; this one returns the btcdeb (see below) command that allows for the transaction to be single-stepped, including the original raw, signed transaction.

Call it with: python2 bsec-3374.py

If the response is Segmentation fault (core dumped) you may be using a system that's too new as per note at the top of this file. Sorry! I don't have an answer as to what would correct it yet.

btcdeb/

Not present in this repository but can be found at https://github.com/kallewoof/btcdeb. This is Kallewoof's debugger that allows single-stepping of BTC transactions. Directory contains a more detailed description of use.

Postscript

Do not use this code in a production environment or on a machine with live keys! I have made no effort to check the safety of anyone's code but my own.

Thank you to Runes K. Svendsen and Andrew Chow for direct help, thank you to the others who created the code I've forked.