X509Certificate2 class for windows Phone 8

问题:

I have a certificate(base64string) in string Certificate

I am extracting that public key from Certificate in both windows Desktop application and windows phone 8 ..to do that I had followed

           X509Certificate2 Cert = new X509Certificate2();

            Cert.Import(Convert.FromBase64String( Certificate, "Test123", X509KeyStorageFlags.Exportable);
            ClsStatic.cer = Cert;

Above code working perfectly in Desktop application.. For windows phone 8 that particular X509Certificate2 class and Exportable is not available.. Is there any other alternative