      """
      return get_callable(settings.CSRF_FAILURE_VIEW)
  
  
  def _get_new_csrf_key():
      return get_random_string(CSRF_KEY_LENGTH)
  
  
  def get_token(request):
      """
      Returns the CSRF token required for a POST form. The token is an
 
</s> remove     return request.META["CSRF_COOKIE"]
 </s> add     return _salt_cipher_secret(csrf_secret) </s> remove CSRF_KEY_LENGTH = 32
 </s> add CSRF_SECRET_LENGTH = 32
CSRF_TOKEN_LENGTH = 2 * CSRF_SECRET_LENGTH
CSRF_ALLOWED_CHARS = string.ascii_letters + string.digits </s> remove     # The csrf token is potentially from an untrusted source, so could have
    # characters that need dealing with.
    _csrf_id_cookie = b"<1>\xc2\xa1"
    _csrf_id = "1"
 </s> add     _csrf_id = _csrf_id_cookie = '1bcdefghij2bcdefghij3bcdefghij4bcdefghij5bcdefghij6bcdefghijABCD' </s> remove form. The malicious user would have to know the nonce, which is user specific
 </s> add form. The malicious user would have to know the secret, which is user specific </s> remove         self.assertEqual(len(csrf_cookie.value), CSRF_KEY_LENGTH)
 </s> add         self.assertEqual(len(csrf_cookie.value), CSRF_TOKEN_LENGTH)

    def test_process_view_token_invalid_chars(self):
        """
        If the token contains non-alphanumeric characters, it is ignored and a
        new token is created.
        """
        token = ('!@#' + self._csrf_id)[:CSRF_TOKEN_LENGTH]
        req = self._get_GET_no_csrf_cookie_request()
        req.COOKIES[settings.CSRF_COOKIE_NAME] = token
        CsrfViewMiddleware().process_view(req, token_view, (), {})
        resp = token_view(req)
        resp2 = CsrfViewMiddleware().process_response(req, resp)
        csrf_cookie = resp2.cookies.get(settings.CSRF_COOKIE_NAME, False)
        self.assertEqual(len(csrf_cookie.value), CSRF_TOKEN_LENGTH)
        self.assertNotEqual(csrf_cookie.value, token)

    def test_process_view_token_invalid_bytes(self):
        """
        If the token contains improperly encoded unicode, it is ignored and a
        new token is created.
        """
        token = (b"<1>\xc2\xa1" + force_bytes(self._csrf_id, 'ascii'))[:CSRF_TOKEN_LENGTH]
        req = self._get_GET_no_csrf_cookie_request()
        req.COOKIES[settings.CSRF_COOKIE_NAME] = token
        # We expect a UnicodeWarning here, because we used broken utf-8 on purpose
        with warnings.catch_warnings():
            warnings.filterwarnings("ignore", category=UnicodeWarning)
            CsrfViewMiddleware().process_view(req, token_view, (), {})
        resp = token_view(req)
        resp2 = CsrfViewMiddleware().process_response(req, resp)
        csrf_cookie = resp2.cookies.get(settings.CSRF_COOKIE_NAME, False)
        self.assertEqual(len(csrf_cookie.value), CSRF_TOKEN_LENGTH)
        self.assertNotEqual(csrf_cookie.value, token)
def _get_new_csrf_string():
    return get_random_string(CSRF_SECRET_LENGTH, allowed_chars=CSRF_ALLOWED_CHARS)


def _salt_cipher_secret(secret):
    """
    Given a secret (assumed to be a string of CSRF_ALLOWED_CHARS), generate a
    token by adding a salt and using it to encrypt the secret.
    """
    salt = _get_new_csrf_string()
    chars = CSRF_ALLOWED_CHARS
    pairs = zip((chars.index(x) for x in secret), (chars.index(x) for x in salt))
    cipher = ''.join(chars[(x + y) % len(chars)] for x, y in pairs)
    return salt + cipher


def _unsalt_cipher_token(token):
    """
    Given a token (assumed to be a string of CSRF_ALLOWED_CHARS, of length
    CSRF_TOKEN_LENGTH, and that its first half is a salt), use it to decrypt
    the second half to produce the original secret.
    """
    salt = token[:CSRF_SECRET_LENGTH]
    token = token[CSRF_SECRET_LENGTH:]
    chars = CSRF_ALLOWED_CHARS
    pairs = zip((chars.index(x) for x in token), (chars.index(x) for x in salt))
    secret = ''.join(chars[x - y] for x, y in pairs)  # Note negative values are ok
    return secret


def _get_new_csrf_token():
    return _salt_cipher_secret(_get_new_csrf_string())
      """
      return get_callable(settings.CSRF_FAILURE_VIEW)
  
  
def _get_new_csrf_string():
    return get_random_string(CSRF_SECRET_LENGTH, allowed_chars=CSRF_ALLOWED_CHARS)


def _salt_cipher_secret(secret):
    """
    Given a secret (assumed to be a string of CSRF_ALLOWED_CHARS), generate a
    token by adding a salt and using it to encrypt the secret.
    """
    salt = _get_new_csrf_string()
    chars = CSRF_ALLOWED_CHARS
    pairs = zip((chars.index(x) for x in secret), (chars.index(x) for x in salt))
    cipher = ''.join(chars[(x + y) % len(chars)] for x, y in pairs)
    return salt + cipher


def _unsalt_cipher_token(token):
    """
    Given a token (assumed to be a string of CSRF_ALLOWED_CHARS, of length
    CSRF_TOKEN_LENGTH, and that its first half is a salt), use it to decrypt
    the second half to produce the original secret.
    """
    salt = token[:CSRF_SECRET_LENGTH]
    token = token[CSRF_SECRET_LENGTH:]
    chars = CSRF_ALLOWED_CHARS
    pairs = zip((chars.index(x) for x in token), (chars.index(x) for x in salt))
    secret = ''.join(chars[x - y] for x, y in pairs)  # Note negative values are ok
    return secret


def _get_new_csrf_token():
    return _salt_cipher_secret(_get_new_csrf_string())
def _get_new_csrf_string():
    return get_random_string(CSRF_SECRET_LENGTH, allowed_chars=CSRF_ALLOWED_CHARS)


def _salt_cipher_secret(secret):
    """
    Given a secret (assumed to be a string of CSRF_ALLOWED_CHARS), generate a
    token by adding a salt and using it to encrypt the secret.
    """
    salt = _get_new_csrf_string()
    chars = CSRF_ALLOWED_CHARS
    pairs = zip((chars.index(x) for x in secret), (chars.index(x) for x in salt))
    cipher = ''.join(chars[(x + y) % len(chars)] for x, y in pairs)
    return salt + cipher


def _unsalt_cipher_token(token):
    """
    Given a token (assumed to be a string of CSRF_ALLOWED_CHARS, of length
    CSRF_TOKEN_LENGTH, and that its first half is a salt), use it to decrypt
    the second half to produce the original secret.
    """
    salt = token[:CSRF_SECRET_LENGTH]
    token = token[CSRF_SECRET_LENGTH:]
    chars = CSRF_ALLOWED_CHARS
    pairs = zip((chars.index(x) for x in token), (chars.index(x) for x in salt))
    secret = ''.join(chars[x - y] for x, y in pairs)  # Note negative values are ok
    return secret


def _get_new_csrf_token():
    return _salt_cipher_secret(_get_new_csrf_string())
  
  
  def get_token(request):
      """
      Returns the CSRF token required for a POST form. The token is an
keep keep keep keep replace replace keep keep keep keep keep
 Fixed #20869 -- made CSRF tokens change every request by salt-encrypting them

Note that the cookie is not changed every request, just the token retrieved
by the `get_token()` method (used also by the `{% csrf_token %}` tag).

While at it, made token validation strict: Where, before, any length was
accepted and non-ASCII chars were ignored, we now treat anything other than
`[A-Za-z0-9]{64}` as invalid (except for 32-char tokens, which, for
backwards-compatibility, are accepted and replaced by 64-char ones).

Thanks Trac user patrys for reporting, github user adambrenecki
for initial patch, Tim Graham for help, and Curtis Maloney,
Collin Anderson, Florian Apolloner, Markus Holtermann & Jon Dufresne
for reviews. 
django/middleware/csrf.py