Pifke's Bitcoin API

This module provides a Python API for Bitcoin mining and research.

JSON-RPC Client

Provided here is yet another JSON-RPC client for talking to a running Bitcoin daemon. Example usage:

from pifkoin import bitcoind

bitcoind.getnewaddress() # returns '1GWgcCuuXXZhtmLpofNeNV9sVEXSxCxAM7'

It will automatically read the RPC connection information from ~/.bitcoin/bitcoin.conf and establish a new connection to the running bitcoind daemon.

Python's standard logging module is used for logging, and most error conditions will result in a BitcoindException with a description of the issue.

To re-use the same connection between commands, or to specify an alternate location for the configuration file, use:

from pifkoin.bitcoind import Bitcoind, BitcoindException

conn = Bitcoind('/foo/bitcoind.conf') # filename is optional
conn.getnewaddress() # returns '1ESa86bBU7CERCQE4VzWBZfwc1LjoW2FnH'
conn.nonexistantcommand() # raises BitcoindException

The latter method of operation can also be used for JSON-RPC methods not explicitly listed in the module, for instance when talking to an alternate implementation such as namecoind.

When instantiating Bitcoind yourself, you can override options from the configuration file by passing them to the constructor:

from pifkoin.bitcoind import Bitcoind

conn = Bitcoind(rpcuser='foo', rpcpassword='bar')

Blockchain Tools

The BlockHeader class provides convenient methods for reading and working with the blockchain. Blocks can be obtained from the running daemon as follows:

from pifkoin.blockchain import BlockHeader

# Using block hash:
bh = BlockHeader.from_blockchain(hash='00000000000006bca5f9613129affe05a1433e45d1087fe3109816aad0156a41')

# Using block height:
bh = BlockHeader.from_blockchain(height=182400)

# Using relative block height:
bh = BlockHeader.from_blockchain(height=-1) # most recent
bh = BlockHeader.from_blockchain(height=-2) # next most recent (and so on)

# For mining:
bh = BlockHeader.from_getwork()

BlockHeader instances contain properties and methods for converting between various formats. For instance, to get the binary string that is hashed as part of the mining operation:

from pifkoin.blockchain import BlockHeader

bh = BlockHeader.from_blockchain(182400)
bh.bytes
# returns '\x01\x00\x00\x00\xfd-Df=\xb1u\x96\x0bU-d\xa5\x1c\x98\xfe\xfb\x82\xa0\x9c7W\x0f\xc0[\x01\x00\x00\x00\x00\x00\x00\xda?\x03\x1d\xf3\xb6\xaa\xb6\xf4\x1e\xc2\x850\x94\x9ddc.\xc3\xee\xc0\x8ec\xc1Z,\xb7\xe0r\x7f1\xd2c\xba\xc7O_\x8b\n\x1ae@\xc8\x1a'

Mining functionality is included for experimentation - it's too slow to be of practical use, but the source code explains what's going on and can be used as a basis for tracing, or for testing new algorithms.

bh.calculate_hash() # recalculates hash using current nonce
bh.find_nonces() # iterates over every possible nonce

SHA256 Implementation

The mining functionality makes use of a pure-Python SHA256 implementation I wrote from scratch to help gain an understanding of the algorithm. It's written for readability and extensibility, not speed; it's orders of magnitude slower than the version in the Python standard library.

The goals of this implementation are to make it easy to trace register values between rounds, and to serve as a basis for reduced-round and alternative algorithms. For instance, the mining code makes the first few rounds loop invariant when iterating over possible nonces, and skips the final few rounds of the algorithm if it determines the resulting hash won't meet the difficulty target. This simulates the behavior of most FPGA and GPU miners; the Python implementation can therefore be used to create test vectors or aid in debugging.