Connecting to Google

Scopes.cs

using Google.Apis.Auth.OAuth2;
using Google.Apis.Admin.Directory.directory_v1;
using Google.Apis.Admin.Directory.directory_v1.Data;
using Google.Apis.Services;

...

string[] extScopes = {
    DirectoryService.Scope.AdminDirectoryUserReadonly,            
    DirectoryService.Scope.AdminDirectoryGroupMemberReadonly
};

...

// JSON Example

GoogleCredential credential;

//cert: Attached Private Key File fileInfo.BinData
using (var stream = new MemoryStream(cert))
{
    credential = GoogleCredential.FromStream(stream)
         .CreateScoped(extScopes));
}
credential = credential.CreateWithUser(AccessAccountEmail);

_ds =  new DirectoryService(new BaseClientService.Initializer()
{
    HttpClientInitializer = credential,
    ApplicationName = appName
});

...