Boltzmann

A python script computing the entropy of Bitcoin transactions and the linkability of their inputs and outputs.

For a description of the metrics :

• Bitcoin Transactions & Privacy (part 1) : https://gist.github.com/LaurentMT/e758767ca4038ac40aaf

• Bitcoin Transactions & Privacy (part 2) : https://gist.github.com/LaurentMT/d361bca6dc52868573a2

• Bitcoin Transactions & Privacy (part 3) : https://gist.github.com/LaurentMT/e8644d5bc903f02613c6

Boltzmann is also available for Java: https://github.com/Samourai-Wallet/efficiency-score

Python versions

Python 3.3.3

Dependencies

• sortedcontainers
• numpy
• python-bitcoinrpc
• mpmath
• sympy
• chainside-btcpy (>=0.5.1)

Installation

Manual installation

Gets the library from Github : https://github.com/Samourai-Wallet/boltzmann/archive/master.zip
Unzips the archive in a temp directory
python setup.py install

Usage

python ludwig.py [--rpc] [--duration=600] [--maxnbtxos=12] [--cjmaxfeeratio=0] [--options=PRECHECK,LINKABILITY,MERGE_FEES,MERGE_INPUTS,MERGE_OUTPUTS] [--txids=8e56317360a548e8ef28ec475878ef70d1371bee3526c017ac22ad61ae5740b8,812bee538bd24d03af7876a77c989b2c236c063a5803c720769fc55222d36b47,...]

[-t OR --txids] = List of txids to be processed.

[-p OR --rpc] = Use bitcoind's RPC interface as source of blockchain data

[-T OR --testnet] = Use testnet3 as source of blockchain data

[-s OR --smartbit] = Use Smartbit as source of blockchain data

[-d OR --duration] = Maximum number of seconds allocated to the processing of a single transaction. Default value is 600 seconds.

[-x OR --maxnbtxos] = Maximum number of inputs or ouputs. Transactions with more than maxnbtxos inputs or outputs are not processed. Default value is 12.

[-r OR --cjmaxfeeratio] = Max intrafees paid by the taker of a coinjoined transaction. Expressed as a percentage of the coinjoined amount.

[-o OR --options] = Options to be applied during processing. Default value is PRECHECK, LINKABILITY, MERGE_INPUTS. Available options are :

• PRECHECK = Checks if deterministic links exist without processing the entropy of the transaction. Similar to Coinjoin Sudoku by K.Atlas.

• LINKABILITY = Computes the entropy of the transaction and the txos linkability matrix.

• MERGE_INPUTS = Merges inputs "controlled" by a same address. Speeds up computations.

• MERGE_OUTPUTS = Merges outputs "controlled" by a same address. Speeds up computations but this option is not recommended.

• MERGE_FEES = Processes fees as an additional output paid by a single participant. May speed up computations.

Troubleshooting

This project requires python 3. If your default python points to python 2, substitute python3 for all instructions in this README.

MERGE_OUTPUTS option is still a work in progress. Results are not always reliable.

MERGE_FEES should only be used if it is known with certainty that all mining fees were paid by a single partificant to the transaction. Not recommended to use, especillay in the case of Stonewall/Stonewallx2 transactions.

If your request is returning no response and you only see "DEBUG: Using remote blockchain.info API" make sure you are typing the commands correctly.

Data Sources

You can use the remote Blockchain.info API for blockchain data (default), bitcoind's local RPC interface using the --rpc command line option, or write your own wrapper.

In order to use bitcoind's RPC interface, you must set these environment variables:

• BOLTZMANN_RPC_USERNAME
• BOLTZMANN_RPC_PASSWORD
• BOLTZMANN_RPC_HOST
• BOLTZMANN_RPC_PORT

Ex. $ export BOLTZMANN_RPC_USERNAME=myusername

You will also need to enable full indexing for bitcoind. This consumes more storage space. See this sample excerpt of a bitcoin.cfg file:

# You must set rpcuser and rpcpassword to secure the JSON-RPC api
rpcuser=myusername
rpcpassword=mysecretpassword_REPLACE_ME
rpcport=8332

#Maintain a full transaction index, used by the getrawtransaction rpc call (default: 0)
txindex=1

Contributors

@LaurentMT @kristovatlas @SamouraiDev

Uses Chainside's btcpy library and Sipa's bech32 reference code for deriving bech32 addresses from public keys (btcpy) and redeem scripts/witness programs (Sipa).

Contributing

Many improvements are needed:

• smarter heuristics to manage intra fees paid/received by participants to coinjoin markets (e.g. joinmarket, ...)
• optimization of the algorithm (parallelization, memorization, ...)
• ...

Help us to make Boltzmann better !

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request

Tip: Don't forget to run python setup.py clean && python setup.py build && python setup.py install after modifying source files.