import os
import base64
import hashlib
import secrets

ALGORITHM = "pbkdf2_sha256"

def crypt(password: str, salt: bytes=None, iterations=260000) -> str:
    if salt is None:
        salt = os.urandom(16)

    hashed = hashlib.pbkdf2_hmac(
        'sha256', bytes(password, 'utf-8'), salt, iterations
    )

    return '$'.join([
        ALGORITHM,
        str(iterations),
        str(base64.b64encode(salt), 'ascii'),
        str(base64.b64encode(hashed), 'ascii')
    ])

def compare(password: str, crypted: str) -> bool:
    parts = crypted.split('$', 4)

    if len(parts) != 4:
        return False

    algorithm, iterations, salt, hashed = parts

    if algorithm != ALGORITHM:
        return False

    new_crypted = crypt(password, base64.b64decode(salt), int(iterations))

    return secrets.compare_digest(crypted, new_crypted)