Brainwallet library

The brainwallet library allows to generate wallets where the private key is computed from a passphrase chosen by the user.
Beside the fact that this method allows computing only one private key (hence only one address), it's very insecure (humans are not a good source of entropy) and discouraged in favor of random HD wallets, but it could be useful to recover some very old wallets.

Built-in algorithms

A brainwallet can be generated using a built-in algorithm. The supported algorithms are:

Enumerative	Description
BrainwalletAlgos.SHA256	Private key is computed from user passphrase using SHA256
BrainwalletAlgos.DOUBLE_SHA256	Private key is computed from user passphrase using double SHA256
BrainwalletAlgos.PBKDF2_HMAC_SHA512	Private key is computed from user passphrase using PBKDF2 HMAC-SHA512
BrainwalletAlgos.SCRYPT	Private key is computed from user passphrase using Scrypt

In case of BrainwalletAlgos.PBKDF2_HMAC_SHA512, these additional parameters can be optionally specified:

• salt: salt for PBKDF2 algorithm (default: empty string)
• itr_num: number of iteration for PBKDF2 algorithm (default: 2097152)

In case of BrainwalletAlgos.SCRYPT, these additional parameters can be optionally specified:

• salt: salt for Scrypt algorithm (default: empty string)
• n: CPU/Memory cost parameter for Scrypt algorithm (default: 131072)
• r: block size parameter for Scrypt algorithm (default: 8)
• p: parallelization parameter for Scrypt algorithm (default: 8) :

Coins

A brainwallet can be generated for all coins supported by Bip44.

The BrainwalletCoins enumerative, used to specify the coin, is just an alias for Bip44Coins.

Generation using built-in algorithms

A wallet can be generated using a built-in algorithm with the Generate method, by specifying the algorithm and coin types.

Code example

from bip_utils import Brainwallet, BrainwalletCoins, BrainwalletAlgos

passphrase = "The quick brown fox jumps over the lazy dog"

# Generate using SHA256 algorithm for Bitcoin
brainwallet_btc = Brainwallet.Generate(
    passphrase,
    BrainwalletCoins.BITCOIN,
    BrainwalletAlgos.SHA256
)

# Generate using Scrypt algorithm for Ethereum with custom salt
brainwallet_eth = Brainwallet.Generate(
    passphrase,
    BrainwalletCoins.ETHEREUM,
    BrainwalletAlgos.SCRYPT,
    salt="custom salt"
)

Generation using custom algorithms

A wallet can be generated using a custom algorithm with the GenerateWithCustomAlgo method, by specifying the algorithm class and coin type.
In order to create a custom algorithm, a class inheriting the IBrainwalletAlgo interface and implementing the ComputePrivateKey method shall be defined.
The output length of the ComputePrivateKey method shall be the length of the private key of the specific coin, usually 32-byte long.

Code example

from typing import Any
from bip_utils import Brainwallet, BrainwalletCoins, IBrainwalletAlgo, Sha512_256

# Custom brainwallet algorithm using SHA512/256 for computing the private key
class BrainwalletCustomAlgo(IBrainwalletAlgo):
    @staticmethod
    def ComputePrivateKey(passphrase: str,
                          **kwargs: Any) -> bytes:
        return Sha512_256.QuickDigest(passphrase)

passphrase = "The quick brown fox jumps over the lazy dog"

# Generate brainwallet for Litecoin with the custom algorithm
brainwallet_ltc = Brainwallet.GenerateWithCustomAlgo(
    passphrase,
    BrainwalletCoins.LITECOIN,
    BrainwalletCustomAlgo
)

Getting keys

The Brainwallet class uses the computed private key to construct a Bip44 object.
Therefore, private and public keys can be use exactly like the Bip44 class.

Code example

from bip_utils import Brainwallet, BrainwalletCoins, BrainwalletAlgos

passphrase = "The quick brown fox jumps over the lazy dog"

brainwallet_btc = Brainwallet.Generate(
    passphrase,
    BrainwalletCoins.BITCOIN,
    BrainwalletAlgos.SHA256
)

print(brainwallet_btc.PrivateKey().Raw().ToHex())
print(brainwallet_btc.PublicKey().ToExtended())
print(brainwallet_btc.PublicKey().ToAddress())