Bitcoin Block Hash Finder

A project that can calculate the hash of a bitcoin block given the block header

How to build and run the project

1. The perfect way

Normally you would install the IntelliJ Idea IDE and import the gradle project. Then click the run icon.

2. On a GNU/Linux system

1. Install JAVA. Both the JDK and the JRE. I compiled the project with JAVA 13, but it is compatible with down to JAVA 8

   • on Ubuntu based systems you can run sudo apt install openjdk-11-jdk or sudo apt install openjdk-8-jdk (I hope)
   • on Arch based systems run sudo pacman -S jdk13-openjdk or the same command for jdk11-openjdk etc.
   • on the rest: I don't know, you are on your own

2. Install the gradle build system

   • Ubuntu sudo apt install gradle
   • Arch sudo pacman -S gradle

3. Install Kotlin

   • Ubuntu snap install kotlin
   • Arch same as above, or if you don't have snap support or hate them sudo pacman -S kotlin

3. On Windows

I can only give you the links and you need to install things manually because Windows doesn't have a serious package manager in 2020

• JAVA: Download the Windows 10 build and then set the JAVA PATH
• Gradle: Follow the instructions for windows
• Kotlin: I recommend following the chocolatey route

How to run the project (without the IDE)

0. Download this repo either with git clone https://github.com/alexandru-balan/btcblock-hash-finder.git or through the download button

1. Navigate to btcblock-hash-finder/

2. Run in this order:

   • ./gradlew build or to speciffy a java folder path ./gradlew build -Dorg.gradle.java.home={path_to_java_folder}, for example I run ./gradlew build -Dorg.gradle.java.home=/usr/lib/jvm/java-13-openjdk/
   • ./gradlew run; I run ./gradlew run -Dorg.gradle.java.home=/usr/lib/jvm/java-13-openjdk/

How to use the project

This project is intended to be just a starting point that I made as a university project. I architected the project to be easy to build through gradle and easy to incorporate in other projects.

The main classes are BlockHeader and Finder and are essential to the project. The BlockHeader class implements a Hashable interface which means that you can use blockHeader.hash() to generate a hash of the block.

Everything was designed with speed in mind so most auxiliary stuff like the files you will find in the extensions package uses bitwise operations. The Finder class is multithreaded and can run through 100_000_000 hashes in a matter of minutes on most modern laptops. (7 minutes on a laptop with Intel i7 3.2GHz and 8 cores)

The playground package is used for the executable part of the project. Please put the Main.kt file there and any other scripts you might want to run.