Gerbera is a Bitcoin offline transaction builder used to generate a raw hex Bitcoin transaction. Generated transaction hex may be later broadcast via online services (e.g. Blockchain.info Broadcast).

What's Supported

• Send to:
  • P2PKH (1-Addresses. Regular and compressed)
  • P2SH (3-Addresses, including SegWit)
• Spend from:
  • P2PKH-produced outputs (1-Addresses)
  • P2SH-P2WPKH segwit outputs (3-Addresses)
• Signature types
  • SIGHASH_ALL
• Multiple inputs from different addresses (signed with different keys)
• Multiple outputs
• Networks
  • MainNet
  • TestNet
• Usage
  • As library
  • Command line application

Help

• Where to find unspent outputs to fill TransactionBuilder.from() method arguments

Quick examples

Build multiple-outputs transaction

The following is an example of how to build a transaction with one input and three (2 custom and 1 for change) outputs.

As library

Transaction transaction = TransactionBuilder.create()
        .from(
                "fb8212db8c6c0509d1892115b0a73acfc3c30668a0f51dc80758cc479e29e67e", // from transaction big endian
                13,                                                                 // from Tout index
                "76a91491b24bf9f5288532960ac687abb035127b1d28a588ac",               // locking script
                40404,                                                              // satoshi
                "5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAnchuDf"               // WIF
        )
        .to("1NZUP3JAc9JkmbvmoTv7nVgZGtyJjirKV1", 17000)                            // output. where and how much (satoshi)
        .to("31h38a54tFMrR8kvVig3R23ntQMoitzkAf", 20000)                            // another output
        .withFee(3000)                                                              // fee (satoshi)
        .changeTo("17Vu7st1U1KwymUKU4jJheHHGRVNqrcfLD")                             // Send change to (if any)
        .build();

Command line tool

$ init mainnet
$ from fb8212db8c6c0509d1892115b0a73acfc3c30668a0f51dc80758cc479e29e67e 13 76a91491b24bf9f5288532960ac687abb035127b1d28a588ac 40404 5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAnchuDf
$ to 1NZUP3JAc9JkmbvmoTv7nVgZGtyJjirKV1 17000
$ to 31h38a54tFMrR8kvVig3R23ntQMoitzkAf 20000
$ withfee 3000
$ changeto 17Vu7st1U1KwymUKU4jJheHHGRVNqrcfLD

If (all inputs) - (all outputs) - fee gives positive value, it will be send to changeTo address.

Build multiple-inputs transaction

The following is an example of how to build a transaction with three inputs and one output:

As library

Transaction transaction = TransactionBuilder.create()
        .from(
                "3722df3eff476fe31db8ae2b52806379bde58e9289026d10e425adc25c2e3f03", // from transaction big endian
                1,                                                                  // from Tout index
                "76a91491b24bf9f5288532960ac687abb035127b1d28a588ac",               // locking script
                3000,                                                               // satoshi
                "5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAnchuDf"               // WIF
        )
        .from(
                "262dc0cba867ba38ec5e92239acbe3074eea3a79105b8e551f60905b1cd79abe", // from transaction big endian
                2,                                                                  // from Tout index
                "76a91406afd46bcdfd22ef94ac122aa11f241244a37ecc88ac",               // locking script
                2500,                                                               // satoshi
                "KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU74NMTptX4"              // WIF
        )
        .from(
                "8b109e31552b7bd3a9c41a30c739eeb0ab90a6ffc92f5a9471e0874acd75e5ba", // from transaction big endian
                12,                                                                 // from Tout index
                "76a91406afd46bcdfd22ef94ac122aa11f241244a37ecc88ac",               // locking script
                10000,                                                              // satoshi
                "KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU74NMTptX4"              // WIF
        )
        .to("1NZUP3JAc9JkmbvmoTv7nVgZGtyJjirKV1", 10000)                            // fee (satoshi)
        .withFee(5500)
        .build();

In case change address is not explicitly included (like in this example), but change is present, an Exception containing change satoshi amount is thrown. Change address must be explicitly declared so that change satoshi are not accidentally spent as fee.

Command line tool

$ init mainnet
$ from 3722df3eff476fe31db8ae2b52806379bde58e9289026d10e425adc25c2e3f03 1  76a91491b24bf9f5288532960ac687abb035127b1d28a588ac 3000  5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAnchuDf
$ from 262dc0cba867ba38ec5e92239acbe3074eea3a79105b8e551f60905b1cd79abe 2  76a91406afd46bcdfd22ef94ac122aa11f241244a37ecc88ac 2500  KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU74NMTptX4
$ from 8b109e31552b7bd3a9c41a30c739eeb0ab90a6ffc92f5a9471e0874acd75e5ba 12 76a91406afd46bcdfd22ef94ac122aa11f241244a37ecc88ac 10000 KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU74NMTptX4
$ withfee 5500
$ to 1NZUP3JAc9JkmbvmoTv7nVgZGtyJjirKV1 10000

Transaction may contain multiple inputs and multiple outputs at the same time.

Build transaction for TestNet

As library

To build a TestNet transaction, create a TransactionBulder with false argument (true is for MainNet, which is default)

Transaction transaction = TransactionBuilder.create(false)
        ...
        ...
        ...
        .build();

Command line tool

$ init testnet

Note that in TestNet, addresses and WIFs have different prefixes.

Get transaction hex

As library

The built transaction object may be used to get raw transaction hex:

transaction.getRawTransaction()

The output is a String that may be submitted to an online service to broadcast the built transaction.

Command line tool

$ raw

Result example:

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

Get transaction field-split representation

As library

The transaction object may be also used to get field-split hex transaction representation that makes reading raw hex easier.

transaction.getSplitTransaction()

Command line tool

$ split

Result example:

Version                  01000000
Input count              01
   Input
      Transaction out    7ee6299e47cc5807c81df5a06806c3c3cf3aa7b0152189d109056c8cdb1282fb
      Tout index         0d000000
      Unlock length      8a
      Unlock             47304402206fb7d70259301222232e8e006cf1d0c6814666e52b5379e04b7cef0d695c4ff202205323e65a65bd74d904d02dfa3d33bfd1d937cd82fadf1a41d9da9d288498163a01410479be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8
      Sequence           ffffffff
Output count             03
   Output (Custom)
      Satoshi            6842000000000000
      Lock length        19
      Lock               76a914ec7eced2c57ed1292bc4eb9bfd13c9f7603bc33888ac
   Output (Custom)
      Satoshi            204e000000000000
      Lock length        17
      Lock               a914000102030405060708090001020304050607080987
   Output (Change)
      Satoshi            9401000000000000
      Lock length        19
      Lock               76a9144747e8746cddb33b0f7f95a90f89f89fb387cbb688ac
Locktime                 00000000

For SegWit transactions (spending SegWit outputs), result example is:

Version                  01000000
Marker                   00
Flag                     01
Input count              02
   Input (Segwit)
      Transaction out    82cb6eb26722118afac52ba256f8753f44de29637bb874fa5d952ebdf952a8cb
      Tout index         02000000
      Unlock length      17
      Unlock             160014033118abb28063208561dc3ce63bdb32880a78ef
      Sequence           ffffffff
   Input
      Transaction out    84b1959dbc3e7dd49b90b5012922a82022fc5cf2df6d0fe23a2d1ad8d615d3cf
      Tout index         00000000
      Unlock length      8b
      Unlock             483045022100c592992fffde118fe8b37e30ee46b7a6ca276be5486c3022e6e20ad4bec5947b02203772a20074aacf7dd3cd37fc36afeba88d8e114fa1e8191bd9bc9b52a38db26a0141047cab4279ec773172c1eeb65b7292149df9bb2f1fb6c7dcacf043aabb893ad19fa90c4286bbb50b211ce6e272dccd511310041c2843af6059d90df4a186782134
      Sequence           ffffffff
Output count             01
   Output (Custom)
      Satoshi            49cdec0600000000
      Lock length        17
      Lock               a914a9974100aeee974a20cda9a2f545704a0ab54fdc87
Witnesses
   Witness               0247304402206bb7c127506f6c25fead2071744014e6111da6af31092e45a1c8eefb73cebb3a02205c2573d4d35bfa5982af5067bcca90473c5cf83844420ab2954d31503abcec9f0121030d7ca27f28ea0b5b4b57605d9ec3f05a2858667529f65797f1cc4b50e2be149f
   Witness               00
Locktime                 00000000

Get additional transaction information

As library

To get additional transaction info (size in bytes and satoshi/byte fee) call the following method of the transaction object:

transaction.getTransactionInfo()

Command line tool

$ info

Result example:

Size (bytes):
  292
Fee (satoshi/byte):
  10.274

For SegWit transactions, fee-per-byte is calculated based on vertual size:

Virtual Size (bytes):
  292
Fee (satoshi/byte):
  10.274

How to compile

First clone the project:

$ git clone https://github.com/aafomin/gerbera.git

Then build a jar:

$ ./gradlew build

The jar gerbera-VERSION.jar will appear in ./build/libs/

How to use

As library

Add the built jar to your project and start from sd.fomin.gerbera.transaction.TransactionBuilder class.

Command line tool

$ java -jar path_to_build_jar/gerbera-VERSION.jar