a71c5438ce
macOS 自带 Python 3.9 链接 LibreSSL，hashlib 不提供 scrypt， register 调用 hash_password 时抛 AttributeError，被 Flask 兜成 500 internal error（登录随之全部失败）。 改用 PBKDF2-HMAC-SHA256（每个 CPython 构建都有），并采用自描述的 存储格式 pbkdf2_sha256$iterations$salt$hash，便于日后迁移算法。 verify_password 仍兼容旧的 salt:hash scrypt 格式（当解释器支持时）。 Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
118 lines
3.5 KiB
Python
118 lines
3.5 KiB
Python
"""
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Authentication helpers: password hashing, JWT signing/verification,
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and the require_auth decorator used by route blueprints.
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Hashes are stored in a self-describing format so the algorithm can be
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migrated later without invalidating existing rows:
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pbkdf2_sha256$<iterations>$<salt_hex>$<hash_hex>
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PBKDF2-HMAC-SHA256 is used because it is available in every CPython build.
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`hashlib.scrypt` is NOT: builds linked against LibreSSL (notably the system
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Python on macOS) omit it, which made registration fail with a 500.
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Legacy `<salt_hex>:<hash_hex>` scrypt hashes are still verified when the
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running interpreter supports scrypt.
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"""
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import hashlib
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import hmac
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import os
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import datetime
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import jwt
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from flask import request, g, jsonify
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from functools import wraps
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from config import JWT_SECRET, JWT_EXPIRY_DAYS
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PBKDF2_ITERATIONS = 200_000
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PBKDF2_PREFIX = "pbkdf2_sha256"
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_SALT_BYTES = 16
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_DK_LEN = 64
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class AuthError(Exception):
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def __init__(self, code, message):
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super().__init__(message)
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self.code = code
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self.message = message
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def _pbkdf2(password: str, salt: bytes, iterations: int) -> str:
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return hashlib.pbkdf2_hmac(
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"sha256", password.encode("utf-8"), salt, iterations, dklen=_DK_LEN
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).hex()
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def hash_password(password: str) -> str:
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salt = os.urandom(_SALT_BYTES)
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derived = _pbkdf2(password, salt, PBKDF2_ITERATIONS)
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return f"{PBKDF2_PREFIX}${PBKDF2_ITERATIONS}${salt.hex()}${derived}"
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def _verify_legacy_scrypt(password: str, stored: str) -> bool:
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"""Verify a pre-migration `salt_hex:hash_hex` scrypt hash, if supported."""
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if not hasattr(hashlib, "scrypt"):
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return False
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salt_hex, hash_hex = stored.split(":", 1)
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try:
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salt = bytes.fromhex(salt_hex)
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except ValueError:
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return False
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derived = hashlib.scrypt(
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password.encode("utf-8"), salt=salt, n=16384, r=8, p=1, dklen=_DK_LEN
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).hex()
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return hmac.compare_digest(derived, hash_hex)
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def verify_password(password: str, stored: str) -> bool:
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if not stored:
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return False
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if stored.startswith(PBKDF2_PREFIX + "$"):
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try:
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_, iterations, salt_hex, hash_hex = stored.split("$", 3)
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salt = bytes.fromhex(salt_hex)
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derived = _pbkdf2(password, salt, int(iterations))
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except (ValueError, TypeError):
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return False
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return hmac.compare_digest(derived, hash_hex)
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if ":" in stored:
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return _verify_legacy_scrypt(password, stored)
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return False
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def sign_token(user_id: str) -> str:
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now = datetime.datetime.utcnow()
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payload = {
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"sub": user_id,
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"iat": now,
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"exp": now + datetime.timedelta(days=JWT_EXPIRY_DAYS),
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}
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return jwt.encode(payload, JWT_SECRET, algorithm="HS256")
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def verify_token(token: str) -> dict:
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payload = jwt.decode(token, JWT_SECRET, algorithms=["HS256"])
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return {"user_id": payload["sub"]}
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def require_auth(f):
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@wraps(f)
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def wrapper(*args, **kwargs):
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auth = request.headers.get("Authorization", "")
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if not auth.startswith("Bearer "):
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return jsonify({"error": "missing or malformed Authorization header"}), 401
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token = auth[7:].strip()
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try:
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data = verify_token(token)
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except jwt.ExpiredSignatureError:
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return jsonify({"error": "token expired"}), 401
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except jwt.InvalidTokenError:
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return jsonify({"error": "invalid token"}), 401
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g.user_id = data["user_id"]
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return f(*args, **kwargs)
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return wrapper
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