Squashed 'paste-framework/' content from commit 34e8684

git-subtree-dir: paste-framework
git-subtree-split: 34e8684c4bc3cebbe177509f42ab4ef5b5425a7a

paste/security/shash.py

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+import hashlib
+import hmac
+import secrets
+from typing import Tuple
+
+SALT_CHARS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+"""
+加盐字符。
+"""
+
+DEFAULT_PBKDF2_ITERATIONS = 260000
+"""
+加密迭代数。
+"""
+
+
+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) -> 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(pwd: 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 pwd: 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, pwd)
+    return f"{actual_method}${salt}${h}"
+
+
+def check_password_hash(pwd_hash: 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 pwd_hash: a hashed string like returned by
+                   :func:`generate_password_hash`
+    :param password: the plaintext password to compare against the hash
+    """
+    if pwd_hash.count("$") < 2:
+        return False
+
+    method, salt, hash_val = pwd_hash.split("$", 2)
+    return hmac.compare_digest(_hash_internal(method, salt, password)[0], hash_val)