Testchain Generator

This tools deterministically generates a synthetic blockchain using Bitcoin's regtest mode. It was written to provide a lean blockchain to run functional and regression against and is used to test BlockSci.

Requirements

• Requires Python >=3.6
• Install Bitcoin Core (bitcoind)
  • Mac: brew install bitcoin
  • Linux: Install instructions (only install the daemon)
• Install secp256k1
• Install Python3 requirements
  • pip3 install -r requirements.txt

Running

The generate_chain.py script takes three arguments:

• --output-dir= specifies where the output should be stored (default: ../files/)
• --chain= specifies whether a Bitcoin or a Bitcoin Cash chain should be generated (options: btc or bch, default: btc)
• --exec= expects a path to the node daemon (default: bitcoind)

If you are using this as a submodule for BlockSci and want to update the Bitcoin (BTC) chain, you would run

python3 generate_chain.py

It will automatically update the BlockSci/test/files/btc/ directory with the new block and json files.

To update the Bitcoin Cash output, you'll need to select bch and provide a path to the Bitcoin ABC daemon executable.

python3 generate_chain.py --chain=bch --exec=<path/to/bitcoincashdaemon>

If you're using this as a standalone tool, you'll probably want to change the output directory for the generated files, e.g.

python3 generate_chain.py --output-dir=.output

Extending the blockchain

New motifs can be created by adding a new class in blockgen/motifs/ that inherits from Generator. Then, add this new class to generate_chain.py. The Generator class provides a number of utility functions, such as:

• next_address(): returns a new Address
• current_address(): returns the current address (the one returned by the last next_address() call)
• fund_address(addr, value): sends value BTC to the address addr
• create_transaction([sources], [recipients]): creates a new transaction using a list of addresses as inputs ([sources]) and another list of addresses as outputs ([recipients])
• generate_block(): creates a new block that includes all transactions created since it was last called