The golden rule of Web application security is to never trust data from\nuntrusted sources. Sometimes it can be useful to pass data through an\nuntrusted medium. Cryptographically signed values can be passed through an\nuntrusted channel safe in the knowledge that any tampering will be detected.
\nDjango provides both a low-level API for signing values and a high-level API\nfor setting and reading signed cookies, one of the most common uses of\nsigning in Web applications.
\n以下のような便利な署名もあります。
\nGenerating "recover my account" URLs for sending to users who have\nlost their password.
Ensuring data stored in hidden form fields has not been tampered with.
Generating one-time secret URLs for allowing temporary access to a\nprotected resource, for example a downloadable file that a user has\npaid for.
SECRET_KEY を守るLink to this heading#startprojectによって新しいプロジェクトを作る際、settings.pyが生成され、ランダムなSECRET_KEYを得ます。この値が、署名されたデータを安全に保つ鍵になります。このキーを安全に保存するとこは極めて重要で、さもなければ攻撃を行うひとたちが彼らの署名を生成するのにも使えるからです。
\nDjango の署名用メソッドは django.core.signing モジュール内にあります。値に著名を行うには、はじめに、次のようにして Signer インスタンスを作成します。
>>> from django.core.signing import Signer\n>>> signer = Signer()\n>>> value = signer.sign('My string')\n>>> value\n'My string:GdMGD6HNQ_qdgxYP8yBZAdAIV1w'\n署名が文字列の最後にコロンに続いて付加されます。元の値を取得するには、unsign メソッドを使用します。
>>> original = signer.unsign(value)\n>>> original\n'My string'\n何らかの理由により署名の値が書き換わってしまった場合、django.core.signing.BadSignature 例外が起こります。
>>> from django.core import signing\n>>> value += 'm'\n>>> try:\n... original = signer.unsign(value)\n... except signing.BadSignature:\n... print("Tampering detected!")\nデフォルトでは、Signer クラスは SECRET_KEY 設定の値を署名生成に利用します。次のように Signer のコンストラクタに任意の値を渡すことで、異なる秘密鍵を使用することもできます。
>>> signer = Signer('my-other-secret')\n>>> value = signer.sign('My string')\n>>> value\n'My string:EkfQJafvGyiofrdGnuthdxImIJw'\nReturns a signer which uses key to generate signatures and sep to\nseparate values. sep cannot be in the URL safe base64 alphabet. This alphabet contains\nalphanumeric characters, hyphens, and underscores.
salt argumentLink to this heading#If you do not wish for every occurrence of a particular string to have the same\nsignature hash, you can use the optional salt argument to the Signer\nclass. Using a salt will seed the signing hash function with both the salt and\nyour SECRET_KEY:
>>> signer = Signer()\n>>> signer.sign('My string')\n'My string:GdMGD6HNQ_qdgxYP8yBZAdAIV1w'\n>>> signer = Signer(salt='extra')\n>>> signer.sign('My string')\n'My string:Ee7vGi-ING6n02gkcJ-QLHg6vFw'\n>>> signer.unsign('My string:Ee7vGi-ING6n02gkcJ-QLHg6vFw')\n'My string'\nUsing salt in this way puts the different signatures into different\nnamespaces. A signature that comes from one namespace (a particular salt\nvalue) cannot be used to validate the same plaintext string in a different\nnamespace that is using a different salt setting. The result is to prevent an\nattacker from using a signed string generated in one place in the code as input\nto another piece of code that is generating (and verifying) signatures using a\ndifferent salt.
\nUnlike your SECRET_KEY, your salt argument does not need to stay\nsecret.
TimestampSigner is a subclass of Signer that appends a signed\ntimestamp to the value. This allows you to confirm that a signed value was\ncreated within a specified period of time:
>>> from datetime import timedelta\n>>> from django.core.signing import TimestampSigner\n>>> signer = TimestampSigner()\n>>> value = signer.sign('hello')\n>>> value\n'hello:1NMg5H:oPVuCqlJWmChm1rA2lyTUtelC-c'\n>>> signer.unsign(value)\n'hello'\n>>> signer.unsign(value, max_age=10)\n...\nSignatureExpired: Signature age 15.5289158821 > 10 seconds\n>>> signer.unsign(value, max_age=20)\n'hello'\n>>> signer.unsign(value, max_age=timedelta(seconds=20))\n'hello'\nSign value and append current timestamp to it.
Checks if value was signed less than max_age seconds ago,\notherwise raises SignatureExpired. The max_age parameter can\naccept an integer or a datetime.timedelta object.
If you wish to protect a list, tuple or dictionary you can do so using the\nsigning module's dumps and loads functions. These imitate Python's\npickle module, but use JSON serialization under the hood. JSON ensures that\neven if your SECRET_KEY is stolen an attacker will not be able\nto execute arbitrary commands by exploiting the pickle format:
>>> from django.core import signing\n>>> value = signing.dumps({"foo": "bar"})\n>>> value\n'eyJmb28iOiJiYXIifQ:1NMg1b:zGcDE4-TCkaeGzLeW9UQwZesciI'\n>>> signing.loads(value)\n{'foo': 'bar'}\nBecause of the nature of JSON (there is no native distinction between lists\nand tuples) if you pass in a tuple, you will get a list from\nsigning.loads(object):
>>> from django.core import signing\n>>> value = signing.dumps(('a','b','c'))\n>>> signing.loads(value)\n['a', 'b', 'c']\nReturns URL-safe, sha1 signed base64 compressed JSON string. Serialized\nobject is signed using TimestampSigner.
Reverse of dumps(), raises BadSignature if signature fails.\nChecks max_age (in seconds) if given.