Error Creating PowerBI on-premise datasource using RestAPI

[BlocksCanFly]

Dear community I recently want to create fully automated process to add and recycle access keys to PowerBI datasource and i have problem with PowerBI Rest API. I can't create or modify datasource because of problems with key value. 

I'm taking public key and modulus from datagateway 

'publicKey': {'exponent': 'AQAB',
  'modulus': '000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000=='
    }

and I'm trying to encode this using python function.

from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.backends import default_backend
import base64

modulus_b64 = ""
exponent_b64 = ""
secret = ""

modulus = int.from_bytes(base64.b64decode(modulus_b64), byteorder='big')
exponent = int.from_bytes(base64.b64decode(exponent_b64), byteorder='big')
public_numbers = rsa.RSAPublicNumbers(exponent, modulus)
public_key = public_numbers.public_key(default_backend())
encrypted_secret = public_key.encrypt(

    secret.encode(),
    padding.OAEP(
        mgf=padding.MGF1(algorithm=hashes.SHA256()),
        algorithm=hashes.SHA256(),
        label=None
    )
)

encrypted_secret_b64 = base64.b64encode(encrypted_secret).decode()

after that i'm sending put request to

https://api.powerbi.com/v1.0/myorg/gateways/{gateway}/datasources

and generate body information accordingly to Microsoft documentation 

{

    "connectionDetails": "{\"extensionDataSourceKind\": \"Databricks\", \"extensionDataSourcePath\": \"{\\\"host\\\": \\\"adb-0000000000000000000.0.azuredatabricks.net\\\", \\\"httpPath\\\": \\\"/sql/1.0/warehouses/0000000000000\\\"}\"}",
    "credentialDetails": {
        "credentialType": "Key",
        "credentials": "{\"credentialData\": [{\"name\": \"key\", \"value\": \"daasd==\"}]}",
        "encryptedConnection": "Encrypted",
        "encryptionAlgorithm": "RSA-OAEP",
        "privacyLevel": "Organizational"
    },
    "dataSourceName": "DB01",
    "dataSourceType": "Extension"
}

i'm allways getting this response. Do you know what might be couse of that? 

{'error': {'code': 'DM_GWPipeline_UnknownError',  'pbi.error': {'code': 'DM_GWPipeline_UnknownError',  'parameters': {},  'details': [{'code': 'DM_ErrorDetailNameCode_UnderlyingErrorMessage',  'detail': {'type': 1,  'value': 'The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters. '}},  {'code': 'DM_ErrorDetailNameCode_UnderlyingHResult',  'detail': {'type': 1, 'value': '-2146233033'}}]}}}

[BlocksCanFly]

Hi i though the same and i used microsoft tamplate from github. PowerBI-Developer-Samples/Python/Encrypt credentials at master · microsoft/PowerBI-Developer-Samples...
and still didn't worked. So i tired to make same request via gui and scout changes and find out this request use different

[lbendlin]

you seem to be decoding one too many times

encrypted_secret_b64 = base64.b64encode(encrypted_secret).decode()