System.Security.Cryptography.MD5CryptoServiceProvider md5CSP = new System.Security.Cryptography.MD5CryptoServiceProvider();//实例化md5

                //获取要加密的字段，并转化为Byte[]数组  

                byte[] testEncrypt = System.Text.Encoding.Unicode.GetBytes(TextBox1.Text.Trim());//取到密码框里的值

                //加密Byte[]数组  

                byte[] resultEncrypt = md5CSP.ComputeHash(testEncrypt);

                //将加密后的数组转化为字段(普通加密)  

                string testResult = System.Text.Encoding.Unicode.GetString(resultEncrypt);

                //作为密码方式加密   

                string EncrypPWD = System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(TextBox1.Text.Trim(), "MD5");//加密完成EncrypPWD  是加密后的字段