using System.Web.Configuration;
/**////打开web.config文件，写入新生成的machineKey
            Configuration config = WebConfigurationManager.OpenWebConfiguration("/");
MachineKeySection configSection = (MachineKeySection)config.GetSection("system.web/machineKey");
configSection.ValidationKey = CreateKey(64);
configSection.DecryptionKey = CreateKey(24);
configSection.Validation = MachineKeyValidation.SHA1;
if (!configSection.SectionInformation.IsLocked)
{
config.Save();
Response.Write("写入成功！");
}
else
{
Response.Write("写入失败！段被锁定！");
}

using System.Security.Cryptography;
/**////生成随机Key 
        public static string CreateKey(int numBytes)
{
RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
byte[] buff = new byte[numBytes];
rng.GetBytes(buff);
System.Text.StringBuilder hexString = new System.Text.StringBuilder(64);
for (int i = 0; i < buff.Length; i++)
{
hexString.Append(String.Format("{0:X2}", buff[i]));
}
return hexString.ToString();
}