Mini Shell
# -*- coding: utf-8 -*-
"""
itsdangerous
~~~~~~~~~~~~
A module that implements various functions to deal with untrusted
sources. Mainly useful for web applications.
:copyright: (c) 2014 by Armin Ronacher and the Django Software Foundation.
:license: BSD, see LICENSE for more details.
"""
import sys
import hmac
import zlib
import time
import base64
import hashlib
import operator
from datetime import datetime
PY2 = sys.version_info[0] == 2
if PY2:
from itertools import izip
text_type = unicode
int_to_byte = chr
number_types = (int, long, float)
else:
from functools import reduce
izip = zip
text_type = str
int_to_byte = operator.methodcaller('to_bytes', 1, 'big')
number_types = (int, float)
try:
import simplejson as json
except ImportError:
import json
class _CompactJSON(object):
"""Wrapper around simplejson that strips whitespace.
"""
def loads(self, payload):
return json.loads(payload)
def dumps(self, obj):
return json.dumps(obj, separators=(',', ':'))
compact_json = _CompactJSON()
# 2011/01/01 in UTC
EPOCH = 1293840000
def want_bytes(s, encoding='utf-8', errors='strict'):
if isinstance(s, text_type):
s = s.encode(encoding, errors)
return s
def is_text_serializer(serializer):
"""Checks wheather a serializer generates text or binary."""
return isinstance(serializer.dumps({}), text_type)
# Starting with 3.3 the standard library has a c-implementation for
# constant time string compares.
_builtin_constant_time_compare = getattr(hmac, 'compare_digest', None)
def constant_time_compare(val1, val2):
"""Returns True if the two strings are equal, False otherwise.
The time taken is independent of the number of characters that match. Do
not use this function for anything else than comparision with known
length targets.
This is should be implemented in C in order to get it completely right.
"""
if _builtin_constant_time_compare is not None:
return _builtin_constant_time_compare(val1, val2)
len_eq = len(val1) == len(val2)
if len_eq:
result = 0
left = val1
else:
result = 1
left = val2
for x, y in izip(bytearray(left), bytearray(val2)):
result |= x ^ y
return result == 0
class BadData(Exception):
"""Raised if bad data of any sort was encountered. This is the
base for all exceptions that itsdangerous is currently using.
.. versionadded:: 0.15
"""
message = None
def __init__(self, message):
Exception.__init__(self, message)
self.message = message
def __str__(self):
return text_type(self.message)
if PY2:
__unicode__ = __str__
def __str__(self):
return self.__unicode__().encode('utf-8')
class BadPayload(BadData):
"""This error is raised in situations when payload is loaded without
checking the signature first and an exception happend as a result of
that. The original exception that caused that will be stored on the
exception as :attr:`original_error`.
This can also happen with a :class:`JSONWebSignatureSerializer` that
is subclassed and uses a different serializer for the payload than
the expected one.
.. versionadded:: 0.15
"""
def __init__(self, message, original_error=None):
BadData.__init__(self, message)
#: If available, the error that indicates why the payload
#: was not valid. This might be `None`.
self.original_error = original_error
class BadSignature(BadData):
"""This error is raised if a signature does not match. As of
itsdangerous 0.14 there are helpful attributes on the exception
instances. You can also catch down the baseclass :exc:`BadData`.
"""
def __init__(self, message, payload=None):
BadData.__init__(self, message)
#: The payload that failed the signature test. In some
#: situations you might still want to inspect this, even if
#: you know it was tampered with.
#:
#: .. versionadded:: 0.14
self.payload = payload
class BadTimeSignature(BadSignature):
"""Raised for time based signatures that fail. This is a subclass
of :class:`BadSignature` so you can catch those down as well.
"""
def __init__(self, message, payload=None, date_signed=None):
BadSignature.__init__(self, message, payload)
#: If the signature expired this exposes the date of when the
#: signature was created. This can be helpful in order to
#: tell the user how long a link has been gone stale.
#:
#: .. versionadded:: 0.14
self.date_signed = date_signed
class BadHeader(BadSignature):
"""Raised if a signed header is invalid in some form. This only
happens for serializers that have a header that goes with the
signature.
.. versionadded:: 0.24
"""
def __init__(self, message, payload=None, header=None,
original_error=None):
BadSignature.__init__(self, message, payload)
#: If the header is actually available but just malformed it
#: might be stored here.
self.header = header
#: If available, the error that indicates why the payload
#: was not valid. This might be `None`.
self.original_error = original_error
class SignatureExpired(BadTimeSignature):
"""Signature timestamp is older than required max_age. This is a
subclass of :exc:`BadTimeSignature` so you can use the baseclass for
catching the error.
"""
def base64_encode(string):
"""base64 encodes a single bytestring (and is tolerant to getting
called with a unicode string).
The resulting bytestring is safe for putting into URLs.
"""
string = want_bytes(string)
return base64.urlsafe_b64encode(string).strip(b'=')
def base64_decode(string):
"""base64 decodes a single bytestring (and is tolerant to getting
called with a unicode string).
The result is also a bytestring.
"""
string = want_bytes(string, encoding='ascii', errors='ignore')
return base64.urlsafe_b64decode(string + b'=' * (-len(string) % 4))
def int_to_bytes(num):
assert num >= 0
rv = []
while num:
rv.append(int_to_byte(num & 0xff))
num >>= 8
return b''.join(reversed(rv))
def bytes_to_int(bytestr):
return reduce(lambda a, b: a << 8 | b, bytearray(bytestr), 0)
class SigningAlgorithm(object):
"""Subclasses of `SigningAlgorithm` have to implement `get_signature` to
provide signature generation functionality.
"""
def get_signature(self, key, value):
"""Returns the signature for the given key and value"""
raise NotImplementedError()
def verify_signature(self, key, value, sig):
"""Verifies the given signature matches the expected signature"""
return constant_time_compare(sig, self.get_signature(key, value))
class NoneAlgorithm(SigningAlgorithm):
"""This class provides a algorithm that does not perform any signing and
returns an empty signature.
"""
def get_signature(self, key, value):
return b''
class HMACAlgorithm(SigningAlgorithm):
"""This class provides signature generation using HMACs."""
#: The digest method to use with the MAC algorithm. This defaults to sha1
#: but can be changed for any other function in the hashlib module.
default_digest_method = staticmethod(hashlib.sha1)
def __init__(self, digest_method=None):
if digest_method is None:
digest_method = self.default_digest_method
self.digest_method = digest_method
def get_signature(self, key, value):
mac = hmac.new(key, msg=value, digestmod=self.digest_method)
return mac.digest()
class Signer(object):
"""This class can sign bytes and unsign it and validate the signature
provided.
Salt can be used to namespace the hash, so that a signed string is only
valid for a given namespace. Leaving this at the default value or re-using
a salt value across different parts of your application where the same
signed value in one part can mean something different in another part
is a security risk.
See :ref:`the-salt` for an example of what the salt is doing and how you
can utilize it.
.. versionadded:: 0.14
`key_derivation` and `digest_method` were added as arguments to the
class constructor.
.. versionadded:: 0.18
`algorithm` was added as an argument to the class constructor.
"""
#: The digest method to use for the signer. This defaults to sha1 but can
#: be changed for any other function in the hashlib module.
#:
#: .. versionchanged:: 0.14
default_digest_method = staticmethod(hashlib.sha1)
#: Controls how the key is derived. The default is Django style
#: concatenation. Possible values are ``concat``, ``django-concat``
#: and ``hmac``. This is used for deriving a key from the secret key
#: with an added salt.
#:
#: .. versionadded:: 0.14
default_key_derivation = 'django-concat'
def __init__(self, secret_key, salt=None, sep='.', key_derivation=None,
digest_method=None, algorithm=None):
self.secret_key = want_bytes(secret_key)
self.sep = sep
self.salt = 'itsdangerous.Signer' if salt is None else salt
if key_derivation is None:
key_derivation = self.default_key_derivation
self.key_derivation = key_derivation
if digest_method is None:
digest_method = self.default_digest_method
self.digest_method = digest_method
if algorithm is None:
algorithm = HMACAlgorithm(self.digest_method)
self.algorithm = algorithm
def derive_key(self):
"""This method is called to derive the key. If you're unhappy with
the default key derivation choices you can override them here.
Keep in mind that the key derivation in itsdangerous is not intended
to be used as a security method to make a complex key out of a short
password. Instead you should use large random secret keys.
"""
salt = want_bytes(self.salt)
if self.key_derivation == 'concat':
return self.digest_method(salt + self.secret_key).digest()
elif self.key_derivation == 'django-concat':
return self.digest_method(salt + b'signer' +
self.secret_key).digest()
elif self.key_derivation == 'hmac':
mac = hmac.new(self.secret_key, digestmod=self.digest_method)
mac.update(salt)
return mac.digest()
elif self.key_derivation == 'none':
return self.secret_key
else:
raise TypeError('Unknown key derivation method')
def get_signature(self, value):
"""Returns the signature for the given value"""
value = want_bytes(value)
key = self.derive_key()
sig = self.algorithm.get_signature(key, value)
return base64_encode(sig)
def sign(self, value):
"""Signs the given string."""
return value + want_bytes(self.sep) + self.get_signature(value)
def verify_signature(self, value, sig):
"""Verifies the signature for the given value."""
key = self.derive_key()
try:
sig = base64_decode(sig)
except Exception:
return False
return self.algorithm.verify_signature(key, value, sig)
def unsign(self, signed_value):
"""Unsigns the given string."""
signed_value = want_bytes(signed_value)
sep = want_bytes(self.sep)
if sep not in signed_value:
raise BadSignature('No %r found in value' % self.sep)
value, sig = signed_value.rsplit(sep, 1)
if self.verify_signature(value, sig):
return value
raise BadSignature('Signature %r does not match' % sig,
payload=value)
def validate(self, signed_value):
"""Just validates the given signed value. Returns `True` if the
signature exists and is valid, `False` otherwise."""
try:
self.unsign(signed_value)
return True
except BadSignature:
return False
class TimestampSigner(Signer):
"""Works like the regular :class:`Signer` but also records the time
of the signing and can be used to expire signatures. The unsign
method can rause a :exc:`SignatureExpired` method if the unsigning
failed because the signature is expired. This exception is a subclass
of :exc:`BadSignature`.
"""
def get_timestamp(self):
"""Returns the current timestamp. This implementation returns the
seconds since 1/1/2011. The function must return an integer.
"""
return int(time.time() - EPOCH)
def timestamp_to_datetime(self, ts):
"""Used to convert the timestamp from `get_timestamp` into a
datetime object.
"""
return datetime.utcfromtimestamp(ts + EPOCH)
def sign(self, value):
"""Signs the given string and also attaches a time information."""
value = want_bytes(value)
timestamp = base64_encode(int_to_bytes(self.get_timestamp()))
sep = want_bytes(self.sep)
value = value + sep + timestamp
return value + sep + self.get_signature(value)
def unsign(self, value, max_age=None, return_timestamp=False):
"""Works like the regular :meth:`~Signer.unsign` but can also
validate the time. See the base docstring of the class for
the general behavior. If `return_timestamp` is set to `True`
the timestamp of the signature will be returned as naive
:class:`datetime.datetime` object in UTC.
"""
try:
result = Signer.unsign(self, value)
sig_error = None
except BadSignature as e:
sig_error = e
result = e.payload or b''
sep = want_bytes(self.sep)
# If there is no timestamp in the result there is something
# seriously wrong. In case there was a signature error, we raise
# that one directly, otherwise we have a weird situation in which
# we shouldn't have come except someone uses a time-based serializer
# on non-timestamp data, so catch that.
if not sep in result:
if sig_error:
raise sig_error
raise BadTimeSignature('timestamp missing', payload=result)
value, timestamp = result.rsplit(sep, 1)
try:
timestamp = bytes_to_int(base64_decode(timestamp))
except Exception:
timestamp = None
# Signature is *not* okay. Raise a proper error now that we have
# split the value and the timestamp.
if sig_error is not None:
raise BadTimeSignature(text_type(sig_error), payload=value,
date_signed=timestamp)
# Signature was okay but the timestamp is actually not there or
# malformed. Should not happen, but well. We handle it nonetheless
if timestamp is None:
raise BadTimeSignature('Malformed timestamp', payload=value)
# Check timestamp is not older than max_age
if max_age is not None:
age = self.get_timestamp() - timestamp
if age > max_age:
raise SignatureExpired(
'Signature age %s > %s seconds' % (age, max_age),
payload=value,
date_signed=self.timestamp_to_datetime(timestamp))
if return_timestamp:
return value, self.timestamp_to_datetime(timestamp)
return value
def validate(self, signed_value, max_age=None):
"""Just validates the given signed value. Returns `True` if the
signature exists and is valid, `False` otherwise."""
try:
self.unsign(signed_value, max_age=max_age)
return True
except BadSignature:
return False
class Serializer(object):
"""This class provides a serialization interface on top of the
signer. It provides a similar API to json/pickle and other modules but is
slightly differently structured internally. If you want to change the
underlying implementation for parsing and loading you have to override the
:meth:`load_payload` and :meth:`dump_payload` functions.
This implementation uses simplejson if available for dumping and loading
and will fall back to the standard library's json module if it's not
available.
Starting with 0.14 you do not need to subclass this class in order to
switch out or customer the :class:`Signer`. You can instead also pass a
different class to the constructor as well as keyword arguments as
dictionary that should be forwarded::
s = Serializer(signer_kwargs={'key_derivation': 'hmac'})
.. versionchanged:: 0.14:
The `signer` and `signer_kwargs` parameters were added to the
constructor.
"""
#: If a serializer module or class is not passed to the constructor
#: this one is picked up. This currently defaults to :mod:`json`.
default_serializer = json
#: The default :class:`Signer` class that is being used by this
#: serializer.
#:
#: .. versionadded:: 0.14
default_signer = Signer
def __init__(self, secret_key, salt=b'itsdangerous', serializer=None,
signer=None, signer_kwargs=None):
self.secret_key = want_bytes(secret_key)
self.salt = want_bytes(salt)
if serializer is None:
serializer = self.default_serializer
self.serializer = serializer
self.is_text_serializer = is_text_serializer(serializer)
if signer is None:
signer = self.default_signer
self.signer = signer
self.signer_kwargs = signer_kwargs or {}
def load_payload(self, payload, serializer=None):
"""Loads the encoded object. This function raises :class:`BadPayload`
if the payload is not valid. The `serializer` parameter can be used to
override the serializer stored on the class. The encoded payload is
always byte based.
"""
if serializer is None:
serializer = self.serializer
is_text = self.is_text_serializer
else:
is_text = is_text_serializer(serializer)
try:
if is_text:
payload = payload.decode('utf-8')
return serializer.loads(payload)
except Exception as e:
raise BadPayload('Could not load the payload because an '
'exception occurred on unserializing the data',
original_error=e)
def dump_payload(self, obj):
"""Dumps the encoded object. The return value is always a
bytestring. If the internal serializer is text based the value
will automatically be encoded to utf-8.
"""
return want_bytes(self.serializer.dumps(obj))
def make_signer(self, salt=None):
"""A method that creates a new instance of the signer to be used.
The default implementation uses the :class:`Signer` baseclass.
"""
if salt is None:
salt = self.salt
return self.signer(self.secret_key, salt=salt, **self.signer_kwargs)
def dumps(self, obj, salt=None):
"""Returns a signed string serialized with the internal serializer.
The return value can be either a byte or unicode string depending
on the format of the internal serializer.
"""
payload = want_bytes(self.dump_payload(obj))
rv = self.make_signer(salt).sign(payload)
if self.is_text_serializer:
rv = rv.decode('utf-8')
return rv
def dump(self, obj, f, salt=None):
"""Like :meth:`dumps` but dumps into a file. The file handle has
to be compatible with what the internal serializer expects.
"""
f.write(self.dumps(obj, salt))
def loads(self, s, salt=None):
"""Reverse of :meth:`dumps`, raises :exc:`BadSignature` if the
signature validation fails.
"""
s = want_bytes(s)
return self.load_payload(self.make_signer(salt).unsign(s))
def load(self, f, salt=None):
"""Like :meth:`loads` but loads from a file."""
return self.loads(f.read(), salt)
def loads_unsafe(self, s, salt=None):
"""Like :meth:`loads` but without verifying the signature. This is
potentially very dangerous to use depending on how your serializer
works. The return value is ``(signature_okay, payload)`` instead of
just the payload. The first item will be a boolean that indicates
if the signature is okay (``True``) or if it failed. This function
never fails.
Use it for debugging only and if you know that your serializer module
is not exploitable (eg: do not use it with a pickle serializer).
.. versionadded:: 0.15
"""
return self._loads_unsafe_impl(s, salt)
def _loads_unsafe_impl(self, s, salt, load_kwargs=None,
load_payload_kwargs=None):
"""Lowlevel helper function to implement :meth:`loads_unsafe` in
serializer subclasses.
"""
try:
return True, self.loads(s, salt=salt, **(load_kwargs or {}))
except BadSignature as e:
if e.payload is None:
return False, None
try:
return False, self.load_payload(e.payload,
**(load_payload_kwargs or {}))
except BadPayload:
return False, None
def load_unsafe(self, f, *args, **kwargs):
"""Like :meth:`loads_unsafe` but loads from a file.
.. versionadded:: 0.15
"""
return self.loads_unsafe(f.read(), *args, **kwargs)
class TimedSerializer(Serializer):
"""Uses the :class:`TimestampSigner` instead of the default
:meth:`Signer`.
"""
default_signer = TimestampSigner
def loads(self, s, max_age=None, return_timestamp=False, salt=None):
"""Reverse of :meth:`dumps`, raises :exc:`BadSignature` if the
signature validation fails. If a `max_age` is provided it will
ensure the signature is not older than that time in seconds. In
case the signature is outdated, :exc:`SignatureExpired` is raised
which is a subclass of :exc:`BadSignature`. All arguments are
forwarded to the signer's :meth:`~TimestampSigner.unsign` method.
"""
base64d, timestamp = self.make_signer(salt) \
.unsign(s, max_age, return_timestamp=True)
payload = self.load_payload(base64d)
if return_timestamp:
return payload, timestamp
return payload
def loads_unsafe(self, s, max_age=None, salt=None):
load_kwargs = {'max_age': max_age}
load_payload_kwargs = {}
return self._loads_unsafe_impl(s, salt, load_kwargs, load_payload_kwargs)
class JSONWebSignatureSerializer(Serializer):
"""This serializer implements JSON Web Signature (JWS) support. Only
supports the JWS Compact Serialization.
"""
jws_algorithms = {
'HS256': HMACAlgorithm(hashlib.sha256),
'HS384': HMACAlgorithm(hashlib.sha384),
'HS512': HMACAlgorithm(hashlib.sha512),
'none': NoneAlgorithm(),
}
#: The default algorithm to use for signature generation
default_algorithm = 'HS256'
default_serializer = compact_json
def __init__(self, secret_key, salt=None, serializer=None,
signer=None, signer_kwargs=None, algorithm_name=None):
Serializer.__init__(self, secret_key, salt, serializer,
signer, signer_kwargs)
if algorithm_name is None:
algorithm_name = self.default_algorithm
self.algorithm_name = algorithm_name
self.algorithm = self.make_algorithm(algorithm_name)
def load_payload(self, payload, return_header=False):
payload = want_bytes(payload)
if b'.' not in payload:
raise BadPayload('No "." found in value')
base64d_header, base64d_payload = payload.split(b'.', 1)
try:
json_header = base64_decode(base64d_header)
except Exception as e:
raise BadHeader('Could not base64 decode the header because of '
'an exception', original_error=e)
try:
json_payload = base64_decode(base64d_payload)
except Exception as e:
raise BadPayload('Could not base64 decode the payload because of '
'an exception', original_error=e)
try:
header = Serializer.load_payload(self, json_header,
serializer=json)
except BadData as e:
raise BadHeader('Could not unserialize header because it was '
'malformed', original_error=e)
if not isinstance(header, dict):
raise BadHeader('Header payload is not a JSON object',
header=header)
payload = Serializer.load_payload(self, json_payload)
if return_header:
return payload, header
return payload
def dump_payload(self, header, obj):
base64d_header = base64_encode(self.serializer.dumps(header))
base64d_payload = base64_encode(self.serializer.dumps(obj))
return base64d_header + b'.' + base64d_payload
def make_algorithm(self, algorithm_name):
try:
return self.jws_algorithms[algorithm_name]
except KeyError:
raise NotImplementedError('Algorithm not supported')
def make_signer(self, salt=None, algorithm=None):
if salt is None:
salt = self.salt
key_derivation = 'none' if salt is None else None
if algorithm is None:
algorithm = self.algorithm
return self.signer(self.secret_key, salt=salt, sep='.',
key_derivation=key_derivation, algorithm=algorithm)
def make_header(self, header_fields):
header = header_fields.copy() if header_fields else {}
header['alg'] = self.algorithm_name
return header
def dumps(self, obj, salt=None, header_fields=None):
"""Like :meth:`~Serializer.dumps` but creates a JSON Web Signature. It
also allows for specifying additional fields to be included in the JWS
Header.
"""
header = self.make_header(header_fields)
signer = self.make_signer(salt, self.algorithm)
return signer.sign(self.dump_payload(header, obj))
def loads(self, s, salt=None, return_header=False):
"""Reverse of :meth:`dumps`. If requested via `return_header` it will
return a tuple of payload and header.
"""
payload, header = self.load_payload(
self.make_signer(salt, self.algorithm).unsign(want_bytes(s)),
return_header=True)
if header.get('alg') != self.algorithm_name:
raise BadHeader('Algorithm mismatch', header=header,
payload=payload)
if return_header:
return payload, header
return payload
def loads_unsafe(self, s, salt=None, return_header=False):
kwargs = {'return_header': return_header}
return self._loads_unsafe_impl(s, salt, kwargs, kwargs)
class TimedJSONWebSignatureSerializer(JSONWebSignatureSerializer):
"""Works like the regular :class:`JSONWebSignatureSerializer` but also
records the time of the signing and can be used to expire signatures.
JWS currently does not specify this behavior but it mentions a possibility
extension like this in the spec. Expiry date is encoded into the header
similarily as specified in `draft-ietf-oauth-json-web-token
<http://self-issued.info/docs/draft-ietf-oauth-json-web-token.html#expDef`_.
The unsign method can raise a :exc:`SignatureExpired` method if the
unsigning failed because the signature is expired. This exception is a
subclass of :exc:`BadSignature`.
"""
DEFAULT_EXPIRES_IN = 3600
def __init__(self, secret_key, expires_in=None, **kwargs):
JSONWebSignatureSerializer.__init__(self, secret_key, **kwargs)
if expires_in is None:
expires_in = self.DEFAULT_EXPIRES_IN
self.expires_in = expires_in
def make_header(self, header_fields):
header = JSONWebSignatureSerializer.make_header(self, header_fields)
iat = self.now()
exp = iat + self.expires_in
header['iat'] = iat
header['exp'] = exp
return header
def loads(self, s, salt=None, return_header=False):
payload, header = JSONWebSignatureSerializer.loads(
self, s, salt, return_header=True)
if 'exp' not in header:
raise BadSignature('Missing expiry date', payload=payload)
if not (isinstance(header['exp'], number_types)
and header['exp'] > 0):
raise BadSignature('expiry date is not an IntDate',
payload=payload)
if header['exp'] < self.now():
raise SignatureExpired('Signature expired', payload=payload,
date_signed=self.get_issue_date(header))
if return_header:
return payload, header
return payload
def get_issue_date(self, header):
rv = header.get('iat')
if isinstance(rv, number_types):
return datetime.utcfromtimestamp(int(rv))
def now(self):
return int(time.time())
class URLSafeSerializerMixin(object):
"""Mixed in with a regular serializer it will attempt to zlib compress
the string to make it shorter if necessary. It will also base64 encode
the string so that it can safely be placed in a URL.
"""
def load_payload(self, payload):
decompress = False
if payload.startswith(b'.'):
payload = payload[1:]
decompress = True
try:
json = base64_decode(payload)
except Exception as e:
raise BadPayload('Could not base64 decode the payload because of '
'an exception', original_error=e)
if decompress:
try:
json = zlib.decompress(json)
except Exception as e:
raise BadPayload('Could not zlib decompress the payload before '
'decoding the payload', original_error=e)
return super(URLSafeSerializerMixin, self).load_payload(json)
def dump_payload(self, obj):
json = super(URLSafeSerializerMixin, self).dump_payload(obj)
is_compressed = False
compressed = zlib.compress(json)
if len(compressed) < (len(json) - 1):
json = compressed
is_compressed = True
base64d = base64_encode(json)
if is_compressed:
base64d = b'.' + base64d
return base64d
class URLSafeSerializer(URLSafeSerializerMixin, Serializer):
"""Works like :class:`Serializer` but dumps and loads into a URL
safe string consisting of the upper and lowercase character of the
alphabet as well as ``'_'``, ``'-'`` and ``'.'``.
"""
default_serializer = compact_json
class URLSafeTimedSerializer(URLSafeSerializerMixin, TimedSerializer):
"""Works like :class:`TimedSerializer` but dumps and loads into a URL
safe string consisting of the upper and lowercase character of the
alphabet as well as ``'_'``, ``'-'`` and ``'.'``.
"""
default_serializer = compact_json
Zerion Mini Shell 1.0