Common API for Ethereum key operations

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

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

python -m pip install eth-keys

>>> from eth_keys import keys
>>> pk = keys.PrivateKey(b'\x01' * 32)
>>> signature = pk.sign_msg(b'a message')
>>> pk
'0x0101010101010101010101010101010101010101010101010101010101010101'
>>> pk.public_key
'0x1b84c5567b126440995d3ed5aaba0565d71e1834604819ff9c17f5e9d5dd078f70beaf8f588b541507fed6a642c5ab42dfdf8120a7f639de5122d47a69a8e8d1'
>>> signature
'0xccda990dba7864b79dc49158fea269338a1cf5747bc4c4bf1b96823e31a0997e7d1e65c06c5bf128b7109e1b4b9ba8d1305dc33f32f624695b2fa8e02c12c1e000'
>>> pk.public_key.to_checksum_address()
'0x1a642f0E3c3aF545E7AcBD38b07251B3990914F1'
>>> signature.verify_msg(b'a message', pk.public_key)
True
>>> signature.recover_public_key_from_msg(b'a message') == pk.public_key
True

The KeyAPI object is the primary API for interacting with the eth-keys libary. The object takes a single optional argument in its constructor which designates what backend will be used for eliptical curve cryptography operations. The built-in backends are:

• eth_keys.backends.NativeECCBackend: A pure python implementation of the ECC operations.
• eth_keys.backends.CoinCurveECCBackend: Uses the coincurve library for ECC operations.

By default, eth-keys will try to use the CoinCurveECCBackend, falling back to the NativeECCBackend if the coincurve library is not available.

Note: The coincurve library is not automatically installed with eth-keys and must be installed separately.

The backend argument can be given in any of the following forms.

• Instance of the backend class
• The backend class
• String with the dot-separated import path for the backend class.

>>> from eth_keys import KeyAPI
>>> from eth_keys.backends import NativeECCBackend
# These are all the same
>>> keys = KeyAPI(NativeECCBackend)
>>> keys = KeyAPI(NativeECCBackend())
>>> keys = KeyAPI('eth_keys.backends.NativeECCBackend')
# Or for the coincurve base backend
>>> keys = KeyAPI('eth_keys.backends.CoinCurveECCBackend')

The backend can also be configured using the environment variable ECC_BACKEND_CLASS which should be set to the dot-separated python import path to the desired backend.

>>> import os
>>> os.environ['ECC_BACKEND_CLASS'] = 'eth_keys.backends.CoinCurveECCBackend'

This method returns a signature for the given message_hash, signed by the provided private_key.

• message_hash: must be a byte string of length 32
• private_key: must be an instance of PrivateKey

Returns True or False based on whether the provided signature is a valid signature for the provided message_hash and public_key.

• message_hash: must be a byte string of length 32
• signature: must be an instance of Signature
• public_key: must be an instance of PublicKey

Returns the PublicKey instances recovered from the given signature and message_hash.

• message_hash: must be a byte string of length 32
• signature: must be an instance of Signature

Returns the PublicKey instances computed from the given private_key instance.

• private_key: must be an instance of PublicKey

There is a common API for the following objects.

• PublicKey
• PrivateKey
• Signature

Each of these objects has all of the following APIs.

• obj.to_bytes(): Returns the object in it's canonical bytes serialization.
• obj.to_hex(): Returns a text string of the hex encoded canonical representation.

The PublicKey class takes a single argument which must be a bytes string with length 64.

Note that there are two other common formats for public keys: 65 bytes with a leading \x04 byte and 33 bytes starting with either \x02 or \x03. To use the former with the PublicKey object, remove the first byte. For the latter, refer to PublicKey.from_compressed_bytes.

The following methods are available:

This classmethod returns a new PublicKey instance computed from its compressed representation.

• compressed_bytes must be a byte string of length 33 starting with \x02 or \x03.

This classmethod returns a new PublicKey instance computed from the given private_key.

• private_key may either be a byte string of length 32 or an instance of the KeyAPI.PrivateKey class.

This classmethod returns a new PublicKey instance computed from the provided message and signature.

• message must be a byte string
• signature must be an instance of KeyAPI.Signature

Same as PublicKey.recover_from_msg except that message_hash should be the Keccak hash of the message.

This method returns True or False based on whether the signature is a valid for the given message.

Same as PublicKey.verify_msg except that message_hash should be the Keccak hash of the message.

Returns the compressed representation of this public key.

Returns the hex encoded ethereum address for this public key.

Returns the ERC55 checksum formatted ethereum address for this public key.

Returns the 20-byte representation of the ethereum address for this public key.

The PrivateKey class takes a single argument which must be a bytes string with length 32.

The following methods and properties are available

This property holds the PublicKey instance coresponding to this private key.

This method returns a signature for the given message in the form of a Signature instance

• message must be a byte string.

Same as PrivateKey.sign except that message_hash should be the Keccak hash of the message.

The Signature class can be instantiated in one of two ways.

• signature_bytes: a bytes string with length 65.
• vrs: a 3-tuple composed of the integers v, r, and s.

Note: If using the signature_bytes to instantiate, the byte string should be encoded as r_bytes | s_bytes | v_bytes where | represents concatenation. r_bytes and s_bytes should be 32 bytes in length. v_bytes should be a single byte \x00 or \x01.

Signatures are expected to use 1 or 0 for their v value.

The following methods and properties are available

This property returns the v value from the signature as an integer.

This property returns the r value from the signature as an integer.

This property returns the s value from the signature as an integer.

This property returns a 3-tuple of (v, r, s).

This method returns True or False based on whether the signature is a valid for the given public key.

• message: must be a byte string.
• public_key: must be an instance of PublicKey

Same as Signature.verify_msg except that message_hash should be the Keccak hash of the message.

This method returns a PublicKey instance recovered from the signature.

• message: must be a byte string.

Same as Signature.recover_public_key_from_msg except that message_hash should be the Keccak hash of the message.

This error is raised during instantaition of any of the PublicKey, PrivateKey or Signature classes if their constructor parameters are invalid.

This error is raised from any of the recover or verify methods involving signatures if the signature is invalid.

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

• Testing
• Pull Requests
• Documentation

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

You can set up your dev environment with:

git clone [email protected]:ethereum/eth-keys.git
cd eth-keys
virtualenv -p python3 venv
. venv/bin/activate
python -m pip install -e ".[dev]"
pre-commit install

To release a new version:

make release bump=$$VERSION_PART_TO_BUMP$$

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. This is typically done from the main branch, except when releasing a beta (in which case the beta is released from main, and the previous stable branch is released from said branch).

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"