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The Ethereum hashing function, keccak256, sometimes (erroneously) called sha3

Note: the similarly named pyethash has a completely different use: it generates proofs of work.

This is a low-level library, intended to be used internally by other Ethereum tools. If you're looking for a convenient hashing tool, check out eth_utils.keccak() which will be a little friendlier, and provide access to other helpful utilities.

Read more in the documentation on ReadTheDocs. View the change log.


pip install eth-hash[pycryptodome]
>>> from import keccak
>>> keccak(b'')

See the docs for more about choosing and installing backends.

Developer setup

If you would like to hack on eth-hash, please check out the Ethereum Development Tactical Manual for information on how we do:

  • Testing
  • Pull Requests
  • Code Style
  • Documentation

Development Environment Setup

You can set up your dev environment with:

git clone
cd eth-hash
virtualenv -p python3 venv
. venv/bin/activate
pip install -e .[dev]

Testing Setup

During development, you might like to have tests run on every file save.

Show flake8 errors on file change:

# Test flake8
when-changed -v -s -r -1 eth_hash/ tests/ -c "clear; flake8 eth_hash tests && echo 'flake8 success' || echo 'error'"

Run multi-process tests in one command, but without color:

# in the project root:
pytest --numprocesses=4 --looponfail --maxfail=1
# the same thing, succinctly:
pytest -n 4 -f --maxfail=1

Run in one thread, with color and desktop notifications:

cd venv
ptw --onfail "notify-send -t 5000 'Test failure ⚠⚠⚠⚠⚠' 'python 3 test on eth-hash failed'" ../tests ../eth_hash

Release setup

For Debian-like systems:

apt install pandoc

To release a new version:

make release bump=$$VERSION_PART_TO_BUMP$$

How to bumpversion

The version format for this repo is {major}.{minor}.{patch} for stable, and {major}.{minor}.{patch}-{stage}.{devnum} for unstable (stage can be alpha or beta).

To issue the next version in line, specify which part to bump, like make release bump=minor or make release bump=devnum.

If you are in a beta version, make release bump=stage will switch to a stable.

To issue an unstable version when the current version is stable, specify the new version explicitly, like make release bump="--new-version 4.0.0-alpha.1 devnum"


The Ethereum hashing function, keccak256, sometimes (erroneously) called sha256 or sha3




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