| import hashlib |
| import hmac |
| import os |
| import posixpath |
| import secrets |
| import typing as t |
|
|
| if t.TYPE_CHECKING: |
| pass |
|
|
| SALT_CHARS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789" |
| DEFAULT_PBKDF2_ITERATIONS = 260000 |
|
|
| _os_alt_seps: t.List[str] = list( |
| sep for sep in [os.path.sep, os.path.altsep] if sep is not None and sep != "/" |
| ) |
|
|
|
|
| def gen_salt(length: int) -> str: |
| """Generate a random string of SALT_CHARS with specified ``length``.""" |
| if length <= 0: |
| raise ValueError("Salt length must be positive") |
|
|
| return "".join(secrets.choice(SALT_CHARS) for _ in range(length)) |
|
|
|
|
| def _hash_internal(method: str, salt: str, password: str) -> t.Tuple[str, str]: |
| """Internal password hash helper. Supports plaintext without salt, |
| unsalted and salted passwords. In case salted passwords are used |
| hmac is used. |
| """ |
| if method == "plain": |
| return password, method |
|
|
| salt = salt.encode("utf-8") |
| password = password.encode("utf-8") |
|
|
| if method.startswith("pbkdf2:"): |
| if not salt: |
| raise ValueError("Salt is required for PBKDF2") |
|
|
| args = method[7:].split(":") |
|
|
| if len(args) not in (1, 2): |
| raise ValueError("Invalid number of arguments for PBKDF2") |
|
|
| method = args.pop(0) |
| iterations = int(args[0] or 0) if args else DEFAULT_PBKDF2_ITERATIONS |
| return ( |
| hashlib.pbkdf2_hmac(method, password, salt, iterations).hex(), |
| f"pbkdf2:{method}:{iterations}", |
| ) |
|
|
| if salt: |
| return hmac.new(salt, password, method).hexdigest(), method |
|
|
| return hashlib.new(method, password).hexdigest(), method |
|
|
|
|
| def generate_password_hash( |
| password: str, method: str = "pbkdf2:sha256", salt_length: int = 16 |
| ) -> str: |
| """Hash a password with the given method and salt with a string of |
| the given length. The format of the string returned includes the method |
| that was used so that :func:`check_password_hash` can check the hash. |
| |
| The format for the hashed string looks like this:: |
| |
| method$salt$hash |
| |
| This method can **not** generate unsalted passwords but it is possible |
| to set param method='plain' in order to enforce plaintext passwords. |
| If a salt is used, hmac is used internally to salt the password. |
| |
| If PBKDF2 is wanted it can be enabled by setting the method to |
| ``pbkdf2:method:iterations`` where iterations is optional:: |
| |
| pbkdf2:sha256:80000$salt$hash |
| pbkdf2:sha256$salt$hash |
| |
| :param password: the password to hash. |
| :param method: the hash method to use (one that hashlib supports). Can |
| optionally be in the format ``pbkdf2:method:iterations`` |
| to enable PBKDF2. |
| :param salt_length: the length of the salt in letters. |
| """ |
| salt = gen_salt(salt_length) if method != "plain" else "" |
| h, actual_method = _hash_internal(method, salt, password) |
| return f"{actual_method}${salt}${h}" |
|
|
|
|
| def check_password_hash(pwhash: str, password: str) -> bool: |
| """Check a password against a given salted and hashed password value. |
| In order to support unsalted legacy passwords this method supports |
| plain text passwords, md5 and sha1 hashes (both salted and unsalted). |
| |
| Returns `True` if the password matched, `False` otherwise. |
| |
| :param pwhash: a hashed string like returned by |
| :func:`generate_password_hash`. |
| :param password: the plaintext password to compare against the hash. |
| """ |
| if pwhash.count("$") < 2: |
| return False |
|
|
| method, salt, hashval = pwhash.split("$", 2) |
| return hmac.compare_digest(_hash_internal(method, salt, password)[0], hashval) |
|
|
|
|
| def safe_join(directory: str, *pathnames: str) -> t.Optional[str]: |
| """Safely join zero or more untrusted path components to a base |
| directory to avoid escaping the base directory. |
| |
| :param directory: The trusted base directory. |
| :param pathnames: The untrusted path components relative to the |
| base directory. |
| :return: A safe path, otherwise ``None``. |
| """ |
| if not directory: |
| |
| |
| directory = "." |
|
|
| parts = [directory] |
|
|
| for filename in pathnames: |
| if filename != "": |
| filename = posixpath.normpath(filename) |
|
|
| if ( |
| any(sep in filename for sep in _os_alt_seps) |
| or os.path.isabs(filename) |
| or filename == ".." |
| or filename.startswith("../") |
| ): |
| return None |
|
|
| parts.append(filename) |
|
|
| return posixpath.join(*parts) |
|
|
