eth-bloom

A python implementation of the bloom filter used by Ethereum.

This library and repository was previously located at https://github.com/pipermerriam/ethereum-bloom. It was transferred to the Ethereum foundation github in November 2017 and renamed to eth-bloom. The PyPI package was also renamed from ethereum-bloom to eth-bloom.

Read more in the documentation below. View the change log.

For more information on what Bloom Filters are, see Wikipedia.

Installation

python -m pip install eth-bloom

Usage

The BloomFilter object

>>> from eth_bloom import BloomFilter
>>> b = BloomFilter()
>>> b'a value' in b  # check whether a value is present
False
>>> b.add(b'a value')  # add a single value
>>> b'a value' in b
True
>>> int(b)  # cast to an integer
3458628712844765018311492773359360516229024449585949240367644166080576879632652362184119765613545163153674691520749911733485693171622325900647078772681584616740134230153806267998022370194756399579977294154062696916779055028045657302214591620589415314367270329881298073237757853875497241510733954508399863880080986777555986663988492288946856978031023631618215522505971170427986911575695114157059398791122395379400594948096
>>> bin(b)  # cast to a binary string
'0b100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'

You can also add an iterable of items to a bloom filter.

>>> b = BloomFilter()
>>> b'value-a' in b
False
>>> b'value-b' in b
False
>>> b.extend([b'value-a', b'value-b'])
>>> b'value-a' in b
True
>>> b'value-b' in b
True

You can initialize a bloom filter from an iterable of byte strings.

>>> b = BloomFilter.from_iterable([b'value-a', b'value-b'])  # initialize from an iterable of values.
>>> b'value-a' in b
True
>>> b'value-b' in b
True

You can initialize a bloom filter from the integer representation of the bloom bits.

>>> b = BloomFilter(3458628712844765018311492773359360516229024449585949240367644166080576879632652362184119765613545163153674691520749911733485693171622325900647078772681584616740134230153806267998022370194756399579977294154062696916779055028045657302214591620589415314367270329881298073237757853875497241510733954508399863880080986777555986663988492288946856978031023631618215522505971170427986911575695114157059398791122395379400594948096)
>>> b'a value' in b
True

You can also merge bloom filters

>>> from eth_bloom import BloomFilter
>>> b1 = BloomFilter()
>>> b2 = BloomFilter()
>>> b1.add(b'a')
>>> b1.add(b'common')
>>> b2.add(b'b')
>>> b2.add(b'common')
>>> b'a' in b1
True
>>> b'b' in b1
False
>>> b'common' in b1
True
>>> b'a' in b2
False
>>> b'b' in b2
True
>>> b'common' in b2
True
>>> b3 = b1 + b2  # using addition
>>> b'a' in b3
True
>>> b'b' in b3
True
>>> b'common' in b3
True
>>> b4 = b1 | b2  # or using bitwise or
>>> b'a' in b4
True
>>> b'b' in b4
True
>>> b'common' in b4
True
>>> b1 |= b2  # or using in-place operations (works with += too)
>>> b'a' in b1
True
>>> b'b' in b1
True
>>> b'common' in b1
True

Developer Setup

If you would like to hack on eth-bloom, please check out the Snake Charmers Tactical Manual for information on how we do:

• Testing
• Pull Requests
• Documentation

We use prek to maintain consistent code style. Once installed, it will run automatically with every commit. You can also run it manually with uv run prek run --all-files. If you need to make a commit that skips the prek checks, you can do so with git commit --no-verify.

Development Environment Setup

You can set up your dev environment with the dev dependency group, which is installed by default when you run uv sync.

git clone git@github.com:ApeWorX/eth-bloom.git
cd eth-bloom
uv sync
uv run prek install

Checks

Run the standard local checks with:

uv build
uv run --group lint ruff check .
uv run --group lint ruff format --check .
uv run --group lint --group test mypy -p eth_bloom
uv run --group test pytest tests

Release setup

To release a new version, create a GitHub Release. The release tag is used by setuptools-scm to derive the package version, and GitHub Actions publishes the built package to PyPI using trusted publishing.