/usr/lib/python2.7/dist-packages/google/auth/jwt.py is in python-google-auth 1.3.0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 | # Copyright 2016 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""JSON Web Tokens
Provides support for creating (encoding) and verifying (decoding) JWTs,
especially JWTs generated and consumed by Google infrastructure.
See `rfc7519`_ for more details on JWTs.
To encode a JWT use :func:`encode`::
from google.auth import crypto
from google.auth import jwt
signer = crypt.Signer(private_key)
payload = {'some': 'payload'}
encoded = jwt.encode(signer, payload)
To decode a JWT and verify claims use :func:`decode`::
claims = jwt.decode(encoded, certs=public_certs)
You can also skip verification::
claims = jwt.decode(encoded, verify=False)
.. _rfc7519: https://tools.ietf.org/html/rfc7519
"""
import base64
import collections
import copy
import datetime
import json
import cachetools
import six
from six.moves import urllib
from google.auth import _helpers
from google.auth import _service_account_info
from google.auth import crypt
from google.auth import exceptions
import google.auth.credentials
_DEFAULT_TOKEN_LIFETIME_SECS = 3600 # 1 hour in seconds
_DEFAULT_MAX_CACHE_SIZE = 10
def encode(signer, payload, header=None, key_id=None):
"""Make a signed JWT.
Args:
signer (google.auth.crypt.Signer): The signer used to sign the JWT.
payload (Mapping[str, str]): The JWT payload.
header (Mapping[str, str]): Additional JWT header payload.
key_id (str): The key id to add to the JWT header. If the
signer has a key id it will be used as the default. If this is
specified it will override the signer's key id.
Returns:
bytes: The encoded JWT.
"""
if header is None:
header = {}
if key_id is None:
key_id = signer.key_id
header.update({'typ': 'JWT', 'alg': 'RS256'})
if key_id is not None:
header['kid'] = key_id
segments = [
base64.urlsafe_b64encode(json.dumps(header).encode('utf-8')),
base64.urlsafe_b64encode(json.dumps(payload).encode('utf-8')),
]
signing_input = b'.'.join(segments)
signature = signer.sign(signing_input)
segments.append(base64.urlsafe_b64encode(signature))
return b'.'.join(segments)
def _decode_jwt_segment(encoded_section):
"""Decodes a single JWT segment."""
section_bytes = _helpers.padded_urlsafe_b64decode(encoded_section)
try:
return json.loads(section_bytes.decode('utf-8'))
except ValueError as caught_exc:
new_exc = ValueError('Can\'t parse segment: {0}'.format(section_bytes))
six.raise_from(new_exc, caught_exc)
def _unverified_decode(token):
"""Decodes a token and does no verification.
Args:
token (Union[str, bytes]): The encoded JWT.
Returns:
Tuple[str, str, str, str]: header, payload, signed_section, and
signature.
Raises:
ValueError: if there are an incorrect amount of segments in the token.
"""
token = _helpers.to_bytes(token)
if token.count(b'.') != 2:
raise ValueError(
'Wrong number of segments in token: {0}'.format(token))
encoded_header, encoded_payload, signature = token.split(b'.')
signed_section = encoded_header + b'.' + encoded_payload
signature = _helpers.padded_urlsafe_b64decode(signature)
# Parse segments
header = _decode_jwt_segment(encoded_header)
payload = _decode_jwt_segment(encoded_payload)
return header, payload, signed_section, signature
def decode_header(token):
"""Return the decoded header of a token.
No verification is done. This is useful to extract the key id from
the header in order to acquire the appropriate certificate to verify
the token.
Args:
token (Union[str, bytes]): the encoded JWT.
Returns:
Mapping: The decoded JWT header.
"""
header, _, _, _ = _unverified_decode(token)
return header
def _verify_iat_and_exp(payload):
"""Verifies the ``iat`` (Issued At) and ``exp`` (Expires) claims in a token
payload.
Args:
payload (Mapping[str, str]): The JWT payload.
Raises:
ValueError: if any checks failed.
"""
now = _helpers.datetime_to_secs(_helpers.utcnow())
# Make sure the iat and exp claims are present.
for key in ('iat', 'exp'):
if key not in payload:
raise ValueError(
'Token does not contain required claim {}'.format(key))
# Make sure the token wasn't issued in the future.
iat = payload['iat']
# Err on the side of accepting a token that is slightly early to account
# for clock skew.
earliest = iat - _helpers.CLOCK_SKEW_SECS
if now < earliest:
raise ValueError('Token used too early, {} < {}'.format(now, iat))
# Make sure the token wasn't issued in the past.
exp = payload['exp']
# Err on the side of accepting a token that is slightly out of date
# to account for clow skew.
latest = exp + _helpers.CLOCK_SKEW_SECS
if latest < now:
raise ValueError('Token expired, {} < {}'.format(latest, now))
def decode(token, certs=None, verify=True, audience=None):
"""Decode and verify a JWT.
Args:
token (str): The encoded JWT.
certs (Union[str, bytes, Mapping[str, Union[str, bytes]]]): The
certificate used to validate the JWT signatyre. If bytes or string,
it must the the public key certificate in PEM format. If a mapping,
it must be a mapping of key IDs to public key certificates in PEM
format. The mapping must contain the same key ID that's specified
in the token's header.
verify (bool): Whether to perform signature and claim validation.
Verification is done by default.
audience (str): The audience claim, 'aud', that this JWT should
contain. If None then the JWT's 'aud' parameter is not verified.
Returns:
Mapping[str, str]: The deserialized JSON payload in the JWT.
Raises:
ValueError: if any verification checks failed.
"""
header, payload, signed_section, signature = _unverified_decode(token)
if not verify:
return payload
# If certs is specified as a dictionary of key IDs to certificates, then
# use the certificate identified by the key ID in the token header.
if isinstance(certs, collections.Mapping):
key_id = header.get('kid')
if key_id:
if key_id not in certs:
raise ValueError(
'Certificate for key id {} not found.'.format(key_id))
certs_to_check = [certs[key_id]]
# If there's no key id in the header, check against all of the certs.
else:
certs_to_check = certs.values()
else:
certs_to_check = certs
# Verify that the signature matches the message.
if not crypt.verify_signature(signed_section, signature, certs_to_check):
raise ValueError('Could not verify token signature.')
# Verify the issued at and created times in the payload.
_verify_iat_and_exp(payload)
# Check audience.
if audience is not None:
claim_audience = payload.get('aud')
if audience != claim_audience:
raise ValueError(
'Token has wrong audience {}, expected {}'.format(
claim_audience, audience))
return payload
class Credentials(google.auth.credentials.Signing,
google.auth.credentials.Credentials):
"""Credentials that use a JWT as the bearer token.
These credentials require an "audience" claim. This claim identifies the
intended recipient of the bearer token.
The constructor arguments determine the claims for the JWT that is
sent with requests. Usually, you'll construct these credentials with
one of the helper constructors as shown in the next section.
To create JWT credentials using a Google service account private key
JSON file::
audience = 'https://pubsub.googleapis.com/google.pubsub.v1.Publisher'
credentials = jwt.Credentials.from_service_account_file(
'service-account.json',
audience=audience)
If you already have the service account file loaded and parsed::
service_account_info = json.load(open('service_account.json'))
credentials = jwt.Credentials.from_service_account_info(
service_account_info,
audience=audience)
Both helper methods pass on arguments to the constructor, so you can
specify the JWT claims::
credentials = jwt.Credentials.from_service_account_file(
'service-account.json',
audience=audience,
additional_claims={'meta': 'data'})
You can also construct the credentials directly if you have a
:class:`~google.auth.crypt.Signer` instance::
credentials = jwt.Credentials(
signer,
issuer='your-issuer',
subject='your-subject',
audience=audience)
The claims are considered immutable. If you want to modify the claims,
you can easily create another instance using :meth:`with_claims`::
new_audience = (
'https://pubsub.googleapis.com/google.pubsub.v1.Subscriber')
new_credentials = credentials.with_claims(audience=new_audience)
"""
def __init__(self, signer, issuer, subject, audience,
additional_claims=None,
token_lifetime=_DEFAULT_TOKEN_LIFETIME_SECS):
"""
Args:
signer (google.auth.crypt.Signer): The signer used to sign JWTs.
issuer (str): The `iss` claim.
subject (str): The `sub` claim.
audience (str): the `aud` claim. The intended audience for the
credentials.
additional_claims (Mapping[str, str]): Any additional claims for
the JWT payload.
token_lifetime (int): The amount of time in seconds for
which the token is valid. Defaults to 1 hour.
"""
super(Credentials, self).__init__()
self._signer = signer
self._issuer = issuer
self._subject = subject
self._audience = audience
self._token_lifetime = token_lifetime
if additional_claims is None:
additional_claims = {}
self._additional_claims = additional_claims
@classmethod
def _from_signer_and_info(cls, signer, info, **kwargs):
"""Creates a Credentials instance from a signer and service account
info.
Args:
signer (google.auth.crypt.Signer): The signer used to sign JWTs.
info (Mapping[str, str]): The service account info.
kwargs: Additional arguments to pass to the constructor.
Returns:
google.auth.jwt.Credentials: The constructed credentials.
Raises:
ValueError: If the info is not in the expected format.
"""
kwargs.setdefault('subject', info['client_email'])
kwargs.setdefault('issuer', info['client_email'])
return cls(signer, **kwargs)
@classmethod
def from_service_account_info(cls, info, **kwargs):
"""Creates an Credentials instance from a dictionary.
Args:
info (Mapping[str, str]): The service account info in Google
format.
kwargs: Additional arguments to pass to the constructor.
Returns:
google.auth.jwt.Credentials: The constructed credentials.
Raises:
ValueError: If the info is not in the expected format.
"""
signer = _service_account_info.from_dict(
info, require=['client_email'])
return cls._from_signer_and_info(signer, info, **kwargs)
@classmethod
def from_service_account_file(cls, filename, **kwargs):
"""Creates a Credentials instance from a service account .json file
in Google format.
Args:
filename (str): The path to the service account .json file.
kwargs: Additional arguments to pass to the constructor.
Returns:
google.auth.jwt.Credentials: The constructed credentials.
"""
info, signer = _service_account_info.from_filename(
filename, require=['client_email'])
return cls._from_signer_and_info(signer, info, **kwargs)
@classmethod
def from_signing_credentials(cls, credentials, audience, **kwargs):
"""Creates a new :class:`google.auth.jwt.Credentials` instance from an
existing :class:`google.auth.credentials.Signing` instance.
The new instance will use the same signer as the existing instance and
will use the existing instance's signer email as the issuer and
subject by default.
Example::
svc_creds = service_account.Credentials.from_service_account_file(
'service_account.json')
audience = (
'https://pubsub.googleapis.com/google.pubsub.v1.Publisher')
jwt_creds = jwt.Credentials.from_signing_credentials(
svc_creds, audience=audience)
Args:
credentials (google.auth.credentials.Signing): The credentials to
use to construct the new credentials.
audience (str): the `aud` claim. The intended audience for the
credentials.
kwargs: Additional arguments to pass to the constructor.
Returns:
google.auth.jwt.Credentials: A new Credentials instance.
"""
kwargs.setdefault('issuer', credentials.signer_email)
kwargs.setdefault('subject', credentials.signer_email)
return cls(
credentials.signer,
audience=audience,
**kwargs)
def with_claims(self, issuer=None, subject=None, audience=None,
additional_claims=None):
"""Returns a copy of these credentials with modified claims.
Args:
issuer (str): The `iss` claim. If unspecified the current issuer
claim will be used.
subject (str): The `sub` claim. If unspecified the current subject
claim will be used.
audience (str): the `aud` claim. If unspecified the current
audience claim will be used.
additional_claims (Mapping[str, str]): Any additional claims for
the JWT payload. This will be merged with the current
additional claims.
Returns:
google.auth.jwt.Credentials: A new credentials instance.
"""
new_additional_claims = copy.deepcopy(self._additional_claims)
new_additional_claims.update(additional_claims or {})
return Credentials(
self._signer,
issuer=issuer if issuer is not None else self._issuer,
subject=subject if subject is not None else self._subject,
audience=audience if audience is not None else self._audience,
additional_claims=new_additional_claims)
def _make_jwt(self):
"""Make a signed JWT.
Returns:
Tuple[bytes, datetime]: The encoded JWT and the expiration.
"""
now = _helpers.utcnow()
lifetime = datetime.timedelta(seconds=self._token_lifetime)
expiry = now + lifetime
payload = {
'iss': self._issuer,
'sub': self._subject,
'iat': _helpers.datetime_to_secs(now),
'exp': _helpers.datetime_to_secs(expiry),
'aud': self._audience,
}
payload.update(self._additional_claims)
jwt = encode(self._signer, payload)
return jwt, expiry
def refresh(self, request):
"""Refreshes the access token.
Args:
request (Any): Unused.
"""
# pylint: disable=unused-argument
# (pylint doesn't correctly recognize overridden methods.)
self.token, self.expiry = self._make_jwt()
@_helpers.copy_docstring(google.auth.credentials.Signing)
def sign_bytes(self, message):
return self._signer.sign(message)
@property
@_helpers.copy_docstring(google.auth.credentials.Signing)
def signer_email(self):
return self._issuer
@property
@_helpers.copy_docstring(google.auth.credentials.Signing)
def signer(self):
return self._signer
class OnDemandCredentials(
google.auth.credentials.Signing,
google.auth.credentials.Credentials):
"""On-demand JWT credentials.
Like :class:`Credentials`, this class uses a JWT as the bearer token for
authentication. However, this class does not require the audience at
construction time. Instead, it will generate a new token on-demand for
each request using the request URI as the audience. It caches tokens
so that multiple requests to the same URI do not incur the overhead
of generating a new token every time.
This behavior is especially useful for `gRPC`_ clients. A gRPC service may
have multiple audience and gRPC clients may not know all of the audiences
required for accessing a particular service. With these credentials,
no knowledge of the audiences is required ahead of time.
.. _grpc: http://www.grpc.io/
"""
def __init__(self, signer, issuer, subject,
additional_claims=None,
token_lifetime=_DEFAULT_TOKEN_LIFETIME_SECS,
max_cache_size=_DEFAULT_MAX_CACHE_SIZE):
"""
Args:
signer (google.auth.crypt.Signer): The signer used to sign JWTs.
issuer (str): The `iss` claim.
subject (str): The `sub` claim.
additional_claims (Mapping[str, str]): Any additional claims for
the JWT payload.
token_lifetime (int): The amount of time in seconds for
which the token is valid. Defaults to 1 hour.
max_cache_size (int): The maximum number of JWT tokens to keep in
cache. Tokens are cached using :class:`cachetools.LRUCache`.
"""
super(OnDemandCredentials, self).__init__()
self._signer = signer
self._issuer = issuer
self._subject = subject
self._token_lifetime = token_lifetime
if additional_claims is None:
additional_claims = {}
self._additional_claims = additional_claims
self._cache = cachetools.LRUCache(maxsize=max_cache_size)
@classmethod
def _from_signer_and_info(cls, signer, info, **kwargs):
"""Creates an OnDemandCredentials instance from a signer and service
account info.
Args:
signer (google.auth.crypt.Signer): The signer used to sign JWTs.
info (Mapping[str, str]): The service account info.
kwargs: Additional arguments to pass to the constructor.
Returns:
google.auth.jwt.OnDemandCredentials: The constructed credentials.
Raises:
ValueError: If the info is not in the expected format.
"""
kwargs.setdefault('subject', info['client_email'])
kwargs.setdefault('issuer', info['client_email'])
return cls(signer, **kwargs)
@classmethod
def from_service_account_info(cls, info, **kwargs):
"""Creates an OnDemandCredentials instance from a dictionary.
Args:
info (Mapping[str, str]): The service account info in Google
format.
kwargs: Additional arguments to pass to the constructor.
Returns:
google.auth.jwt.OnDemandCredentials: The constructed credentials.
Raises:
ValueError: If the info is not in the expected format.
"""
signer = _service_account_info.from_dict(
info, require=['client_email'])
return cls._from_signer_and_info(signer, info, **kwargs)
@classmethod
def from_service_account_file(cls, filename, **kwargs):
"""Creates an OnDemandCredentials instance from a service account .json
file in Google format.
Args:
filename (str): The path to the service account .json file.
kwargs: Additional arguments to pass to the constructor.
Returns:
google.auth.jwt.OnDemandCredentials: The constructed credentials.
"""
info, signer = _service_account_info.from_filename(
filename, require=['client_email'])
return cls._from_signer_and_info(signer, info, **kwargs)
@classmethod
def from_signing_credentials(cls, credentials, **kwargs):
"""Creates a new :class:`google.auth.jwt.OnDemandCredentials` instance
from an existing :class:`google.auth.credentials.Signing` instance.
The new instance will use the same signer as the existing instance and
will use the existing instance's signer email as the issuer and
subject by default.
Example::
svc_creds = service_account.Credentials.from_service_account_file(
'service_account.json')
jwt_creds = jwt.OnDemandCredentials.from_signing_credentials(
svc_creds)
Args:
credentials (google.auth.credentials.Signing): The credentials to
use to construct the new credentials.
kwargs: Additional arguments to pass to the constructor.
Returns:
google.auth.jwt.Credentials: A new Credentials instance.
"""
kwargs.setdefault('issuer', credentials.signer_email)
kwargs.setdefault('subject', credentials.signer_email)
return cls(credentials.signer, **kwargs)
def with_claims(self, issuer=None, subject=None, additional_claims=None):
"""Returns a copy of these credentials with modified claims.
Args:
issuer (str): The `iss` claim. If unspecified the current issuer
claim will be used.
subject (str): The `sub` claim. If unspecified the current subject
claim will be used.
additional_claims (Mapping[str, str]): Any additional claims for
the JWT payload. This will be merged with the current
additional claims.
Returns:
google.auth.jwt.OnDemandCredentials: A new credentials instance.
"""
new_additional_claims = copy.deepcopy(self._additional_claims)
new_additional_claims.update(additional_claims or {})
return OnDemandCredentials(
self._signer,
issuer=issuer if issuer is not None else self._issuer,
subject=subject if subject is not None else self._subject,
additional_claims=new_additional_claims,
max_cache_size=self._cache.maxsize)
@property
def valid(self):
"""Checks the validity of the credentials.
These credentials are always valid because it generates tokens on
demand.
"""
return True
def _make_jwt_for_audience(self, audience):
"""Make a new JWT for the given audience.
Args:
audience (str): The intended audience.
Returns:
Tuple[bytes, datetime]: The encoded JWT and the expiration.
"""
now = _helpers.utcnow()
lifetime = datetime.timedelta(seconds=self._token_lifetime)
expiry = now + lifetime
payload = {
'iss': self._issuer,
'sub': self._subject,
'iat': _helpers.datetime_to_secs(now),
'exp': _helpers.datetime_to_secs(expiry),
'aud': audience,
}
payload.update(self._additional_claims)
jwt = encode(self._signer, payload)
return jwt, expiry
def _get_jwt_for_audience(self, audience):
"""Get a JWT For a given audience.
If there is already an existing, non-expired token in the cache for
the audience, that token is used. Otherwise, a new token will be
created.
Args:
audience (str): The intended audience.
Returns:
bytes: The encoded JWT.
"""
token, expiry = self._cache.get(audience, (None, None))
if token is None or expiry < _helpers.utcnow():
token, expiry = self._make_jwt_for_audience(audience)
self._cache[audience] = token, expiry
return token
def refresh(self, request):
"""Raises an exception, these credentials can not be directly
refreshed.
Args:
request (Any): Unused.
Raises:
google.auth.RefreshError
"""
# pylint: disable=unused-argument
# (pylint doesn't correctly recognize overridden methods.)
raise exceptions.RefreshError(
'OnDemandCredentials can not be directly refreshed.')
def before_request(self, request, method, url, headers):
"""Performs credential-specific before request logic.
Args:
request (Any): Unused. JWT credentials do not need to make an
HTTP request to refresh.
method (str): The request's HTTP method.
url (str): The request's URI. This is used as the audience claim
when generating the JWT.
headers (Mapping): The request's headers.
"""
# pylint: disable=unused-argument
# (pylint doesn't correctly recognize overridden methods.)
parts = urllib.parse.urlsplit(url)
# Strip query string and fragment
audience = urllib.parse.urlunsplit(
(parts.scheme, parts.netloc, parts.path, None, None))
token = self._get_jwt_for_audience(audience)
self.apply(headers, token=token)
@_helpers.copy_docstring(google.auth.credentials.Signing)
def sign_bytes(self, message):
return self._signer.sign(message)
@property
@_helpers.copy_docstring(google.auth.credentials.Signing)
def signer_email(self):
return self._issuer
@property
@_helpers.copy_docstring(google.auth.credentials.Signing)
def signer(self):
return self._signer
|