using System.Security;
using System.Security.Cryptography;
private void btnmd5_Click(object sender, EventArgs e)
        {
            MD5 md5 = new MD5CryptoServiceProvider();
            byte[] palindata = Encoding.Default.GetBytes(txtyuan.Text);//将要加密的字符串转换为字节数组
            byte[] encryptdata=md5.ComputeHash(palindata);//将字符串加密后也转换为字符数组
            txtjiami.Text = Convert.ToBase64String(encryptdata);//将加密后的字节数组转换为加密字符串
        }

private void btnjm_Click(object sender, EventArgs e)
        {
            param = new CspParameters();
            param.KeyContainerName = "Olive";//密匙容器的名称，保持加密解密一致才能解密成功
            using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(param))
            {
                byte[] plaindata = Encoding.Default.GetBytes(txtyuan.Text);//将要加密的字符串转换为字节数组
                byte[] encryptdata = rsa.Encrypt(plaindata, false);//将加密后的字节数据转换为新的加密字节数组
                txtjiami.Text =Convert.ToBase64String(encryptdata);//将加密后的字节数组转换为字符串
            }
        }

private void btnjiemi_Click(object sender, EventArgs e)
        {
            param = new CspParameters();
            param.KeyContainerName = "Olive";
            using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(param))
            {
                byte[] encryptdata = Convert.FromBase64String(this.txtjiami.Text);
                byte[] decryptdata = rsa.Decrypt(encryptdata, false);
                txthjiemi.Text = Encoding.Default.GetString(decryptdata);
            }
        }

RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
            using (StreamWriter sw = new StreamWriter(@"D:\PublicKey.xml"))//产生公匙（也包含私匙）
            {
                sw.WriteLine(rsa.ToXmlString(true));
            }
           using (StreamWriter sw = new StreamWriter(@"D:\PrivateKey.xml"))//产生私匙
            {
                sw.WriteLine(rsa.ToXmlString(false));
            }

private void button2_Click(object sender, EventArgs e)
        {
            MemoryStream ms = new MemoryStream();//先创建 一个内存流
            CryptoStream cryStream = new CryptoStream(ms, DesCSP.CreateEncryptor(), CryptoStreamMode.Write);//将内存流连接到加密转换流
            StreamWriter sw = new StreamWriter(cryStream);
            sw.WriteLine(txtyuan.Text);//将要加密的字符串写入加密转换流
            sw.Close();
            cryStream.Close();
            buffer = ms.ToArray();//将加密后的流转换为字节数组
            txtjiami.Text =Convert.ToBase64String(buffer);//将加密后的字节数组转换为字符串
}

private void button1_Click(object sender, EventArgs e)
        {
            MemoryStream ms = new MemoryStream(buffer);//将加密后的字节数据加入内存流中
            CryptoStream cryStream = new CryptoStream(ms, DesCSP.CreateDecryptor(), CryptoStreamMode.Read);//内存流连接到解密流中
            StreamReader sr = new StreamReader(cryStream);
            txthjiemi.Text = sr.ReadLine();//将解密流读取为字符串
            sr.Close();
            cryStream.Close();
            ms.Close();
        }