finished 0021

jiangqideng · jiangqideng · commit be9e6e18d9fc · 2017-02-10T18:16:52.000+08:00
diff --git a/jiangqideng/python练习题（答案）.ipynb b/jiangqideng/python练习题（答案）.ipynb
@@ -2305,13 +2305,62 @@
    ]
   },
   {
-   "cell_type": "code",
-   "execution_count": null,
+   "cell_type": "markdown",
    "metadata": {
     "collapsed": true
    },
-   "outputs": [],
-   "source": []
+   "source": [
+    "### 第0021题\n",
+    "\n",
+    "通常，登陆某个网站或者 APP，需要使用用户名和密码。密码是如何加密后存储起来的呢？请使用 Python 对密码加密。\n",
+    "\n",
+    "+ 阅读资料 [用户密码的存储与 Python 示例](http://zhuoqiang.me/password-storage-and-python-example.html)\n",
+    "\n",
+    "+ 阅读资料 [Hashing Strings with Python](http://pythoncentral.io/hashing-strings-with-python/)\n",
+    "\n",
+    "+ 阅读资料 [Python's safest method to store and retrieve passwords from a database](http://stackoverflow.com/questions/2572099/pythons-safest-method-to-store-and-retrieve-passwords-from-a-database)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 33,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "my_password: 12345678\n",
+      "hashed:  �m���byjJ�\u0018��=5��S��I�>��o�P}iFAZ!��h�^\n",
+      "True\n",
+      "False\n"
+     ]
+    }
+   ],
+   "source": [
+    "import os\n",
+    "from hashlib import sha256\n",
+    "from hmac import HMAC\n",
+    "\n",
+    "def encrypt_password(password, salt=None):\n",
+    "    if salt is None:\n",
+    "        salt = os.urandom(8)\n",
+    "    for i in xrange(10):\n",
+    "        result = HMAC(password, salt, sha256).digest()\n",
+    "    return salt + result\n",
+    "\n",
+    "def validate_password(hashed, input_password):\n",
+    "    return hashed == encrypt_password(input_password, salt=hashed[:8])\n",
+    "\n",
+    "my_password = '12345678'\n",
+    "hashed = encrypt_password(my_password)\n",
+    "print 'my_password:', my_password\n",
+    "print 'hashed: ', hashed\n",
+    "print validate_password(hashed, my_password)\n",
+    "print validate_password(hashed, '1234567')"
+   ]
   }
  ],
  "metadata": {
