private void PostToMerchantServer()
{
var braintree = new Braintree(PublicKey);
var parameters = new Dictionary<string, object>
{
{"cc_number", braintree.Encrypt(CreditCardNumber.Text)},
{"cc_exp_date", braintree.Encrypt(ExpirationDate.Text)},
{"cc_cvv", braintree.Encrypt(Cvv.Text)}
};
var client = new BraintreeHttpClient(_merchantServerUrl, UploadStringCompleted);
client.Post(parameters);
}