Is it possible to use json key instead of p12 key for service account credentials?

Question

I am using "Google.Apis.Bigquery.v2 Client Library" with C#.

I am authorizing to Google BigQuery using "Service Account" (see http://www.afterlogic.com/mailbee-net/docs/OAuth2GoogleServiceAccounts.html). To create the X509 certificate I use the p12 key from the Google Developers Console. However, right now the json key is the default. Can I use it instead the p12 key?

I have the following code:

    string serviceAccountEmail = "[email protected]";

X509Certificate2 certificate;
using (Stream stream = new FileStream(@"C:\key.p12", FileMode.Open, FileAccess.Read, FileShare.Read))
{
    using (MemoryStream ms = new MemoryStream())
    {
        stream.CopyTo(ms);
        certificate = new X509Certificate2(ms.ToArray(), "notasecret", X509KeyStorageFlags.Exportable);
    }
}

// Create credentials
ServiceAccountCredential credential = new ServiceAccountCredential(
    new ServiceAccountCredential.Initializer(serviceAccountEmail)
    {
        Scopes = new[] {
        BigqueryService.Scope.Bigquery,
        BigqueryService.Scope.CloudPlatform,
    },
    }.FromCertificate(certificate));

// Create the service
BaseClientService.Initializer initializer = new BaseClientService.Initializer()
{
    HttpClientInitializer = credential,
    ApplicationName = "My Application",
    GZipEnabled = true,
};

BigqueryService service = new BigqueryService(initializer);
var projects = service.Projects.List().Execute();

Answer 1

It is now possible (I used v 1.13.1.0 of Google APIs).

Example for BigQuery:

GoogleCredential credential;
using (Stream stream = new FileStream(@"C:\mykey.json", FileMode.Open, FileAccess.Read, FileShare.Read))
{
    credential = GoogleCredential.FromStream(stream);
}

string[] scopes = new string[] {
    BigqueryService.Scope.Bigquery,
    BigqueryService.Scope.CloudPlatform, 
};
credential = credential.CreateScoped(scopes);

BaseClientService.Initializer initializer = new BaseClientService.Initializer()
{
    HttpClientInitializer = (IConfigurableHttpClientInitializer)credential,
    ApplicationName = "My Application",
    GZipEnabled = true,
};
BigqueryService service = new BigqueryService(initializer);

Example for Google Sheets:

GoogleCredential credential;
using (Stream stream = new FileStream(@"mykey.json", FileMode.Open, FileAccess.Read, FileShare.Read))
{
    credential = GoogleCredential.FromStream(stream);
}
credential = credential.CreateScoped(new[] { 
    "https://spreadsheets.google.com/feeds", 
    "https://docs.google.com/feeds" });

string bearer;
try
{
    Task<string> task = ((ITokenAccess)credential).GetAccessTokenForRequestAsync();
    task.Wait();
    bearer = task.Result;
}
catch (AggregateException ex)
{
    throw ex.InnerException;
}

GDataRequestFactory requestFactory = new GDataRequestFactory("My Application");
requestFactory.CustomHeaders.Add(string.Format(CultureInfo.InvariantCulture, "Authorization: Bearer {0}", bearer));

SpreadsheetsService service = new SpreadsheetsService("My Application");
service.RequestFactory = requestFactory;