BitCrack Documentation

BitCrack is a tool for brute-forcing Bitcoin private keys, often used for solving the Bitcoin puzzle transaction.

Depending on your hardware, use the appropriate executable:

• cuBitCrack.exe for NVIDIA CUDA devices.
• clBitCrack.exe for OpenCL devices (Note: clBitCrack.exe is experimental and may have bugs on some AMD and Intel devices).

Basic syntax: xxBitCrack.exe [OPTIONS] [TARGETS]

Where [TARGETS] are one or more Bitcoin addresses.

xxBitCrack.exe 1FshYsUh3mqgsG29XpZ23eLjWV8Ur3VwH

GPU performance is affected by three main parameters. Tuning these can increase the keys per second (MKey/s):

1. blocks (-b): Should be a multiple of the number of compute units on the device. Default is 32.
2. threads (-t): The number of threads in a block. Must be a multiple of 32. Default is 256.
3. points (-p): The number of keys each thread will process. Increasing this value increases performance asymptotically, though it causes the kernel to run longer.

Example of manual tuning:

xxBitCrack.exe -b 32 -t 256 -p 16 1FshYsUh3mqgsG29XpZ23eLjWV8Ur3VwH

Build BitCrack using make with the following commands:

Build CUDA version:

make BUILD_CUDA=1

Build OpenCL version:

make BUILD_OPENCL=1

Build both versions:

make BUILD_CUDA=1 BUILD_OPENCL=1

Dependencies

• Visual Studio 2019
• For CUDA: CUDA Toolkit 10.1
• For OpenCL: An OpenCL SDK (included in CUDA toolkit)

Build Steps

1. Open the Visual Studio solution.
2. To build for OpenCL: Build the clKeyFinder project.
3. To build for CUDA: Build the cuKeyFinder project.

Note: By default, NVIDIA OpenCL headers are used. You can configure the header and library path for OpenCL in the BitCrack.props property sheet.

BitCrack is a command-line tool used to search for private keys corresponding to specific Bitcoin addresses. You can provide addresses directly as command-line arguments or read them from a file. The tool supports various hardware acceleration methods (CUDA/OpenCL) and allows fine-grained control over the keyspace, device parameters, and compression types.

BitCrack [OPTIONS] [TARGETS]

# Example: Search for a specific address using a specific device
BitCrack --device 0 1A1zP1eP5QGefi2DMPTfS5ht1W58ieEtuv

# Example: Search using a file of addresses
BitCrack --in addresses.txt

You can use the --keyspace option to define exactly which private keys to search. This allows you to start at a specific key or define a specific range.

To start at a specific private key:

xxBitCrack.exe --keyspace 766519C977831678F0000000000 1FshYsUh3mqgsG29XpZ23eLjWV8Ur3VwH

To search a specific range (e.g., from 80000000 to ffffffff):

xxBitCrack.exe --keyspace 80000000:ffffffff 1FshYsUh3mqgsG29XpZ23eLjWV8Ur3VwH

BitCrack can save its current state to a checkpoint file and resume from that state later. This prevents losing progress if the process is interrupted. Use --continue FILE to point to a previously saved checkpoint file. The checkpoint file stores the current key, keyspace boundaries, device settings, and elapsed time.

# To save progress (implicitly handled if --continue is provided and running)
# To resume from a checkpoint
BitCrack --continue checkpoint.txt 1A1zP1eP5QGefi2DMPTfS5ht1W58ieEtuv

The --keyspace option allows you to define the range of private keys to search. All values must be in hexadecimal format. Supported formats include:

• START:END: A specific range.
• START:+COUNT: From a start point for a specific number of keys.
• START: From a start point to the end of the curve.
• :END: From the beginning of the curve to an end point.
• :+COUNT: The first N keys of the curve.

# Example: Search from hex START to hex END
BitCrack --keyspace 1000:2000

# Example: Search from hex START for 500 keys
BitCrack --keyspace 1000:+500

To distribute a large keyspace across multiple machines or processes, use the --share M/N option. This divides the current keyspace into N equal shares and instructs BitCrack to process only the M-th share. This is useful for parallelizing searches across different devices or nodes.

# Example: Process the 1st share out of 4 total shares
BitCrack --share 1/4 1A1zP1eP5QGefi2DMPTfS5ht1W58ieEtuv