eth-keyfile

A library for handling the encrypted keyfiles used to store ethereum private keys

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

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

Quickstart

python -m pip install eth-keyfile

Documentation

eth_keyfile.load_keyfile(path_or_file_obj) --> keyfile_json

Takes either a filesystem path represented as a string or a file object and returns the parsed keyfile json as a python dictionary.

>>> from eth_keyfile import load_keyfile
>>> load_keyfile('path/to-my-keystore/keystore.json')
{
    "crypto" : {
        "cipher" : "aes-128-ctr",
        "cipherparams" : {
            "iv" : "6087dab2f9fdbbfaddc31a909735c1e6"
        },
        "ciphertext" : "5318b4d5bcd28de64ee5559e671353e16f075ecae9f99c7a79a38af5f869aa46",
        "kdf" : "pbkdf2",
        "kdfparams" : {
            "c" : 262144,
            "dklen" : 32,
            "prf" : "hmac-sha256",
            "salt" : "ae3cd4e7013836a3df6bd7241b12db061dbe2c6785853cce422d148a624ce0bd"
        },
        "mac" : "517ead924a9d0dc3124507e3393d175ce3ff7c1e96529c6c555ce9e51205e9b2"
    },
    "id" : "3198bc9c-6672-5ab3-d995-4942343ae5b6",
    "version" : 3
}

eth_keyfile.create_keyfile_json(private_key, password, kdf="pbkdf2", work_factor=None, salt_size=16) --> keyfile_json

Takes the following parameters:

• private_key: A bytestring of length 32. See note below.
• password: A bytestring which will be the password that can be used to decrypt the resulting keyfile.
• version: An int to select the keyfile standard to use. Supported are 3 and 4. Defaults to 3.
• kdf: A str to select the key derivation function. Allowed values are pbkdf2 and scrypt. By default, pbkdf2 will be used.
• iterations: An int to set the work factor which will be used for the given key derivation function. By default 1000000 will be used for pbkdf2 and 262144 for scrypt.
• salt_size: An int to define the size of the randomly-generated salt in bytes. Defaults to 16 for v3 and 32 for v4.
• description: (v4 only) An optional str for a user-defined message, generally to be able to tell one keyfile from another. Defaults to an empty string.
• path: (v4 only) An optional str to indicate where in the key-tree a key originates from. Defaults to an empty string. See EIP-2334 for more detail.

Returns the keyfile json as a python dictionary.

>>> private_key = b'\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01'
>>> create_keyfile_json(private_key, b'foo')
{
    "address" : "1a642f0e3c3af545e7acbd38b07251b3990914f1",
    "crypto" : {
        "cipher" : "aes-128-ctr",
        "cipherparams" : {
            "iv" : "6087dab2f9fdbbfaddc31a909735c1e6"
        },
        "ciphertext" : "5318b4d5bcd28de64ee5559e671353e16f075ecae9f99c7a79a38af5f869aa46",
        "kdf" : "pbkdf2",
        "kdfparams" : {
            "c" : 262144,
            "dklen" : 32,
            "prf" : "hmac-sha256",
            "salt" : "ae3cd4e7013836a3df6bd7241b12db061dbe2c6785853cce422d148a624ce0bd"
        },
        "mac" : "517ead924a9d0dc3124507e3393d175ce3ff7c1e96529c6c555ce9e51205e9b2"
    },
    "id" : "3198bc9c-6672-5ab3-d995-4942343ae5b6",
    "version" : 3
}

>>> create_keyfile_json(private_key, b'foo', version=4)
 {
    'crypto': {
        'checksum': {
            'function': 'sha256',
            'message': '66a4883a8017c9ef2854acc0c46af6cc8943de5bcf6bb501a2d6a932a91c5333',
            'params': {}
        },
        'cipher': {
            'function': 'aes-128-ctr',
            'message': '584fbbc86d65a92c1e0dfcaa3ba46c4790d31382c5dba25c94acfa2ae6e2687d',
            'params': {
                'iv': 'f948a84c4072cc3f38c82f6f672fa8a9'
            }
        },
        'kdf': {
            'function': 'pbkdf2',
            'message': '',
            'params': {
                'c': 1000000,
                'dklen': 32,
                'prf': 'hmac-sha256',
                'salt': 'd0a1d8a34e7b8bdffbe34e1152ee0bcf3dba64c6e1539cf2bce2ef6995061757'
            }
        }
    },
    'description': '',
    'path': '',
    'pubkey': 'aa1a1c26055a329817a5759d877a2795f9499b97d6056edde0eea39512f24e8bc874b4471f0501127abb1ea0d9f68ac1',
    'uuid': '92c3f383-e8ea-47a1-a1d7-55adccfae8fe',
    'version': 4}

A note on private keys

Valid values for private keys are more limited with the keyfile v4 standard.

In v3, a valid key must be less than '0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141', a limit which most users are unlikely to run into.

In v4, the key must be less than '0x73eda753299d7d483339d80809a1d80553bda402fffe5bfeffffffff00000001'.

These limits are due to the cryptographic functions used. secp256k1 is used for v3, while bls12-381 is used for v4.

eth_keyfile.decode_keyfile_json(keyfile_json, password) --> private_key

Takes the keyfile json as a python dictionary and the password for the keyfile, returning the decoded private key.

>>> keyfile_json = {
...     "crypto" : {
...         "cipher" : "aes-128-ctr",
...         "cipherparams" : {
...             "iv" : "6087dab2f9fdbbfaddc31a909735c1e6"
...         },
...         "ciphertext" : "5318b4d5bcd28de64ee5559e671353e16f075ecae9f99c7a79a38af5f869aa46",
...         "kdf" : "pbkdf2",
...         "kdfparams" : {
...             "c" : 262144,
...             "dklen" : 32,
...             "prf" : "hmac-sha256",
...             "salt" : "ae3cd4e7013836a3df6bd7241b12db061dbe2c6785853cce422d148a624ce0bd"
...         },
...         "mac" : "517ead924a9d0dc3124507e3393d175ce3ff7c1e96529c6c555ce9e51205e9b2"
...     },
...     "id" : "3198bc9c-6672-5ab3-d995-4942343ae5b6",
...     "version" : 3
... }
>>> decode_keyfile_json(keyfile_json, b'foo')
b'\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01'

eth_keyfile.extract_key_from_keyfile(path_or_file_obj, password) --> private_key

Takes a filesystem path represented by a string or a file object and the password for the keyfile. Returns the private key as a bytestring.

>>> extract_key_from_keyfile('path/to-my-keystore/keyfile.json', b'foo')
b'\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01'

Developer Setup

If you would like to hack on eth-keyfile, 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.

Development Environment Setup

You can set up your dev environment with:

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

Release setup

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. 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"