Using Power BI REST API to create a Cosmos DB datasource

[bohara2000]

I am getting a "DMTS_InvalidEncryptionAlgorithmError"  code when I try to programmatically create a CosmosDB datasource in Power BI using the REST APIs.  

Here's the code I try to use, minus credentials

POST https://api.powerbi.com/v1.0/myorg/gateways/[gateway id]/datasources

Authorization: Bearer [token]

Content-type: application/json

{

    "datasourceName":  "MAD365-DS-SGMC",

    "credentialDetails":  {

                          "encryptedConnection":  "Encrypted",

                          "credentialType":  "Key",

                          "credentials":  "{\"credentialData\":[{\"name\":\"key\", \"value\": \"[Cosmos DB key]\"}

                        ]}",

                          "privacyLevel":  "None",

                          "encryptionAlgorithm":  "None"

    },

    "dataSourceType":  "Extension",

    "connectionDetails":  "{\"extensionDataSourceKind\": \"DocumentDB\", \"extensionDataSourcePath\":\"[Cosmos DB URI]:443\"}"

}

Any help would be greatly appreciated. Thanks.

[Jayendran]

Hi @bohara2000 ,

You need to encrypt the credentials and call the API due to the PowerBI security.

Please see the below reference

https://docs.microsoft.com/en-us/power-bi/developer/encrypt-credentials

The below C# code helps you to do the encryption 

public static class AsymmetricKeyEncryptionHelper
{

    private const int SegmentLength = 85;
    private const int EncryptedLength = 128;

    public static string EncodeCredentials(string credentials, string publicKeyExponent, string publicKeyModulus)
    {
        using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(EncryptedLength * 8))
        {
            var parameters = rsa.ExportParameters(false);
            parameters.Exponent = Convert.FromBase64String(publicKeyExponent);
            parameters.Modulus = Convert.FromBase64String(publicKeyModulus);
            rsa.ImportParameters(parameters);
            return Encrypt(credentials, rsa);
        }
    }

    private static string Encrypt(string plainText, RSACryptoServiceProvider rsa)
    {
        byte[] plainTextArray = Encoding.UTF8.GetBytes(plainText);

        // Split the message into different segments, each segment's length is 85. So the result may be 85,85,85,20.
        bool hasIncompleteSegment = plainTextArray.Length % SegmentLength != 0;

        int segmentNumber = (!hasIncompleteSegment) ? (plainTextArray.Length / SegmentLength) : ((plainTextArray.Length / SegmentLength) + 1);

        byte[] encryptedData = new byte[segmentNumber * EncryptedLength];
        int encryptedDataPosition = 0;

        for (var i = 0; i < segmentNumber; i++)
        {
            int lengthToCopy;

            if (i == segmentNumber - 1 && hasIncompleteSegment)
                lengthToCopy = plainTextArray.Length % SegmentLength;
            else
                lengthToCopy = SegmentLength;

            var segment = new byte[lengthToCopy];

            Array.Copy(plainTextArray, i * SegmentLength, segment, 0, lengthToCopy);

            var segmentEncryptedResult = rsa.Encrypt(segment, true);

            Array.Copy(segmentEncryptedResult, 0, encryptedData, encryptedDataPosition, segmentEncryptedResult.Length);

            encryptedDataPosition += segmentEncryptedResult.Length;
        }

        return Convert.ToBase64String(encryptedData);
    }
}