AW.Pay.Core.AliPay.RSASign C# (CSharp) Method

        private string RSASign(string prestr, string privateKey, string input_charset)
        {
            try
            {
                return RSAFromPkcs8.sign(prestr, privateKey, input_charset);
            }
            catch (Exception e)
            {
                return e.Message;
            }
        }