Invalid Padding running example.py

[hemebond]

This issue is for a:

- [x] bug report
- [ ] feature request
- [ ] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)

Minimal steps to reproduce

export AZURE_STORAGE_CONNECTIONSTRING="........"
git clone https://github.com/Azure-Samples/azure-sdk-for-python-storage-blob-upload-download.git
pip install -r requirements.txt
python example.py

Any log messages given by the failure

$ python example.py 
Incorrect padding

Expected/desired behavior

Runs example stuff.

OS and Version?

$ uname -a
Linux excession 5.10.0-8-amd64 #1 SMP Debian 5.10.46-4 (2021-08-03) x86_64 GNU/Linux

Versions

$ python --version
Python 3.8.8

$ pip list
Package              Version
-------------------- ---------
azure-common         1.1.27
azure-storage-blob   2.1.0
azure-storage-common 2.1.0
certifi              2021.5.30
cffi                 1.14.6
charset-normalizer   2.0.5
cryptography         3.4.8
idna                 3.2
pip                  20.2.3
pycparser            2.20
python-dateutil      2.8.2
requests             2.26.0
setuptools           49.2.1
six                  1.16.0
urllib3              1.26.6

Mention any other details that might be useful

Same issue as #17 and an error that occurs in other contexts (django-storages)

Here's an example of using BlobBlockService manually in iPython:

In [4]: blob_service_client = BlockBlobService(account_name=AZURE_ACCOUNT_NAME, account_key=AZURE_ACCOUNT_KEY)

In [5]: blob_service_client.exists(AZURE_CONTAINER)
---------------------------------------------------------------------------
Error                                     Traceback (most recent call last)
.../site-packages/azure/storage/common/_auth.py in _add_authorization_header(self, request, string_to_sign)
     68         try:
---> 69             signature = _sign_string(self.account_key, string_to_sign)
     70             auth_string = 'SharedKey ' + self.account_name + ':' + signature

.../site-packages/azure/storage/common/_common_conversion.py in _sign_string(key, string_to_sign, key_is_base64)
     90     if key_is_base64:
---> 91         key = _decode_base64_to_bytes(key)
     92     else:

.../site-packages/azure/storage/common/_common_conversion.py in _decode_base64_to_bytes(data)
     80         data = data.encode('utf-8')
---> 81     return base64.b64decode(data)
     82 

/usr/lib/python3.9/base64.py in b64decode(s, altchars, validate)
     86         raise binascii.Error('Non-base64 digit found')
---> 87     return binascii.a2b_base64(s)
     88 

Error: Incorrect padding

During handling of the above exception, another exception occurred:

AzureSigningError                         Traceback (most recent call last)
<ipython-input-5-7d5053a16991> in <module>
----> 1 blob_service_client.exists(AZURE_CONTAINER)

.../site-packages/azure/storage/blob/baseblobservice.py in exists(self, container_name, blob_name, snapshot, timeout)
   1757             expected_errors = [_CONTAINER_NOT_FOUND_ERROR_CODE] if blob_name is None \
   1758                 else [_CONTAINER_NOT_FOUND_ERROR_CODE, _BLOB_NOT_FOUND_ERROR_CODE]
-> 1759             self._perform_request(request, expected_errors=expected_errors)
   1760 
   1761             return True

.../site-packages/azure/storage/common/storageclient.py in _perform_request(self, request, parser, parser_args, operation_context, expected_errors)
    400                                 client_request_id_prefix,
    401                                 exception_str_in_one_line)
--> 402                     raise ex
    403 
    404                 logger.info("%s Operation failed: checking if the operation should be retried. "

.../site-packages/azure/storage/common/storageclient.py in _perform_request(self, request, parser, parser_args, operation_context, expected_errors)
    372                 except AzureException as ex:
    373                     retry_context.exception = ex
--> 374                     raise ex
    375                 except Exception as ex:
    376                     retry_context.exception = ex

.../site-packages/azure/storage/common/storageclient.py in _perform_request(self, request, parser, parser_args, operation_context, expected_errors)
    312                     try:
    313                         # request can be signed individually
--> 314                         self.authentication.sign_request(request)
    315                     except AttributeError:
    316                         # session can also be signed

.../site-packages/azure/storage/common/_auth.py in sign_request(self, request)
     90             self._get_canonicalized_resource_query(request)
     91 
---> 92         self._add_authorization_header(request, string_to_sign)
     93         logger.debug("String_to_sign=%s", string_to_sign)
     94 

.../site-packages/azure/storage/common/_auth.py in _add_authorization_header(self, request, string_to_sign)
     73             # Wrap any error that occurred as signing error
     74             # Doing so will clarify/locate the source of problem
---> 75             raise _wrap_exception(ex, AzureSigningError)
     76 
     77     def sign_request(self, request):

AzureSigningError: Incorrect padding

[lmazuel]

@tasherif-msft would be better owner than me on this.

[tasherif-msft]

Hi @hemebond, thanks for all the details.
@jalauzon-msft could you please have a look at this