Extract private key from Terra Station Wallet export

extract_private.py

#!/usr/bin/env python

# 
# Extract private key from Terra Station Wallet exported private key
#
# python ./extract_private.py "DATA FROM 'Export Wallet' - 'Private Key'" "your password"
#
# Your private key base64 encoded will be print on stdout
#
import sys
import json
from base64 import b64decode, b64encode
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
from cryptography.hazmat.primitives import padding


def decrypt_key(*, key: bytes, iv: bytes, ciphered: bytes) -> bytes:
    cipher = Cipher(algorithms.AES(key), modes.CBC(iv), backend=default_backend())
    d = cipher.decryptor()
    padded = d.update(ciphered) + d.finalize()
    # remove padding
    unpadder = padding.PKCS7(128).unpadder()
    plain = unpadder.update(padded) + unpadder.finalize()
    plain = plain.decode("utf-8")
    return bytes.fromhex(plain)

def derive_key(*, password: str, salt: bytes) -> bytes:
    kdf = PBKDF2HMAC(algorithm=hashes.SHA1(), length=32, salt=salt, iterations=100)
    key = kdf.derive(password.encode("utf-8"))
    return key

def parse_encrypted_key(message: str):
    salt = bytes.fromhex(message[:32])
    iv = bytes.fromhex(message[32:64])
    ciphered = b64decode(message[64:])
    return {
        "salt": salt,
        "iv": iv,
        "ciphered": ciphered
    }

def extract_encrypted_key(message: str):
    message = b64decode(message)
    data = json.loads(message)
    return data["encrypted_key"]

def get_key(*, message: str, password: str) -> str:
    encrypted_key = extract_encrypted_key(message)
    data  = parse_encrypted_key(encrypted_key)
    kek = derive_key(password=password, salt=data["salt"])
    key = decrypt_key(key=kek, iv=data["iv"], ciphered=data["ciphered"])
    return b64encode(key).decode("utf-8")


if __name__ == "__main__":
    message = sys.argv[1]
    password = sys.argv[2]
    output = get_key(message=message, password=password)
    print(output)