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Diffstat (limited to 'python/werkzeug/security.py')
| -rw-r--r-- | python/werkzeug/security.py | 241 |
1 files changed, 241 insertions, 0 deletions
diff --git a/python/werkzeug/security.py b/python/werkzeug/security.py new file mode 100644 index 0000000..1842afd --- /dev/null +++ b/python/werkzeug/security.py @@ -0,0 +1,241 @@ +# -*- coding: utf-8 -*- +""" + werkzeug.security + ~~~~~~~~~~~~~~~~~ + + Security related helpers such as secure password hashing tools. + + :copyright: 2007 Pallets + :license: BSD-3-Clause +""" +import codecs +import hashlib +import hmac +import os +import posixpath +from random import SystemRandom +from struct import Struct + +from ._compat import izip +from ._compat import PY2 +from ._compat import range_type +from ._compat import text_type +from ._compat import to_bytes +from ._compat import to_native + +SALT_CHARS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789" +DEFAULT_PBKDF2_ITERATIONS = 150000 + +_pack_int = Struct(">I").pack +_builtin_safe_str_cmp = getattr(hmac, "compare_digest", None) +_sys_rng = SystemRandom() +_os_alt_seps = list( + sep for sep in [os.path.sep, os.path.altsep] if sep not in (None, "/") +) + + +def pbkdf2_hex( + data, salt, iterations=DEFAULT_PBKDF2_ITERATIONS, keylen=None, hashfunc=None +): + """Like :func:`pbkdf2_bin`, but returns a hex-encoded string. + + .. versionadded:: 0.9 + + :param data: the data to derive. + :param salt: the salt for the derivation. + :param iterations: the number of iterations. + :param keylen: the length of the resulting key. If not provided, + the digest size will be used. + :param hashfunc: the hash function to use. This can either be the + string name of a known hash function, or a function + from the hashlib module. Defaults to sha256. + """ + rv = pbkdf2_bin(data, salt, iterations, keylen, hashfunc) + return to_native(codecs.encode(rv, "hex_codec")) + + +def pbkdf2_bin( + data, salt, iterations=DEFAULT_PBKDF2_ITERATIONS, keylen=None, hashfunc=None +): + """Returns a binary digest for the PBKDF2 hash algorithm of `data` + with the given `salt`. It iterates `iterations` times and produces a + key of `keylen` bytes. By default, SHA-256 is used as hash function; + a different hashlib `hashfunc` can be provided. + + .. versionadded:: 0.9 + + :param data: the data to derive. + :param salt: the salt for the derivation. + :param iterations: the number of iterations. + :param keylen: the length of the resulting key. If not provided + the digest size will be used. + :param hashfunc: the hash function to use. This can either be the + string name of a known hash function or a function + from the hashlib module. Defaults to sha256. + """ + if not hashfunc: + hashfunc = "sha256" + + data = to_bytes(data) + salt = to_bytes(salt) + + if callable(hashfunc): + _test_hash = hashfunc() + hash_name = getattr(_test_hash, "name", None) + else: + hash_name = hashfunc + return hashlib.pbkdf2_hmac(hash_name, data, salt, iterations, keylen) + + +def safe_str_cmp(a, b): + """This function compares strings in somewhat constant time. This + requires that the length of at least one string is known in advance. + + Returns `True` if the two strings are equal, or `False` if they are not. + + .. versionadded:: 0.7 + """ + if isinstance(a, text_type): + a = a.encode("utf-8") + if isinstance(b, text_type): + b = b.encode("utf-8") + + if _builtin_safe_str_cmp is not None: + return _builtin_safe_str_cmp(a, b) + + if len(a) != len(b): + return False + + rv = 0 + if PY2: + for x, y in izip(a, b): + rv |= ord(x) ^ ord(y) + else: + for x, y in izip(a, b): + rv |= x ^ y + + return rv == 0 + + +def gen_salt(length): + """Generate a random string of SALT_CHARS with specified ``length``.""" + if length <= 0: + raise ValueError("Salt length must be positive") + return "".join(_sys_rng.choice(SALT_CHARS) for _ in range_type(length)) + + +def _hash_internal(method, salt, password): + """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 + + if isinstance(password, text_type): + password = password.encode("utf-8") + + if method.startswith("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 = args and int(args[0] or 0) or DEFAULT_PBKDF2_ITERATIONS + is_pbkdf2 = True + actual_method = "pbkdf2:%s:%d" % (method, iterations) + else: + is_pbkdf2 = False + actual_method = method + + if is_pbkdf2: + if not salt: + raise ValueError("Salt is required for PBKDF2") + rv = pbkdf2_hex(password, salt, iterations, hashfunc=method) + elif salt: + if isinstance(salt, text_type): + salt = salt.encode("utf-8") + mac = _create_mac(salt, password, method) + rv = mac.hexdigest() + else: + rv = hashlib.new(method, password).hexdigest() + return rv, actual_method + + +def _create_mac(key, msg, method): + if callable(method): + return hmac.HMAC(key, msg, method) + + def hashfunc(d=b""): + return hashlib.new(method, d) + + # Python 2.7 used ``hasattr(digestmod, '__call__')`` + # to detect if hashfunc is callable + hashfunc.__call__ = hashfunc + return hmac.HMAC(key, msg, hashfunc) + + +def generate_password_hash(password, method="pbkdf2:sha256", salt_length=8): + """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 "%s$%s$%s" % (actual_method, salt, h) + + +def check_password_hash(pwhash, password): + """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 safe_str_cmp(_hash_internal(method, salt, password)[0], hashval) + + +def safe_join(directory, *pathnames): + """Safely join `directory` and one or more untrusted `pathnames`. If this + cannot be done, this function returns ``None``. + + :param directory: the base directory. + :param pathnames: the untrusted pathnames relative to that directory. + """ + parts = [directory] + for filename in pathnames: + if filename != "": + filename = posixpath.normpath(filename) + for sep in _os_alt_seps: + if sep in filename: + return None + if os.path.isabs(filename) or filename == ".." or filename.startswith("../"): + return None + parts.append(filename) + return posixpath.join(*parts) |