RSA 实际应用中是：接收方产生公钥和私钥，发送方用其公钥加密，再把加密后的内容发送给接收方。

CspParameters 的名称空间是：

System.Security.Cryptography

CspParameters cpSend = new CspParameters(); //Csp = Cryptography Service Provider
CspParameters cpReceive = new CspParameters();
cpSend.KeyContainerName = "SendTestContainer";
cpReceive.KeyContainerName = "ReceiveTestContainer";

RSACryptoServiceProvider rsaSend = new RSACryptoServiceProvider(cpSend); ;
RSACryptoServiceProvider rsaReceive = new RSACryptoServiceProvider(cpReceive);

rsaSend.FromXmlString(rsaReceive.ToXmlString(false)); //发送方使用接收方给它的公钥进行加密

string plaintext = "前几天我碰到一个朋友，约我跟马贼打架，我立马答应了他，因为我觉得这件事好无聊。";
byte[] ciphertext = rsaSend.Encrypt(System.Text.Encoding.UTF8.GetBytes(plaintext), false); //加密后
byte[] decryption = rsaReceive.Decrypt(ciphertext, false); //解密后

lbl.Width = 760;
lbl.Text = "";
lbl.Text += Convert.ToBase64String(ciphertext) + "<br />"; //显示加密后的
lbl.Text += System.Text.Encoding.UTF8.GetString(decryption) + "<br />"; //显示解密后的
lbl.Text += Server.HtmlEncode(rsaSend.ToXmlString(false)) + "<br />"; //显示发送方公钥
lbl.Text += Server.HtmlEncode(rsaReceive.ToXmlString(true)) + "<br />"; //显示接收方公钥和私钥
lbl.Text += Server.HtmlEncode(rsaReceive.ToXmlString(false)) + "<br />";  //显示接收方公钥

rsaSend.PersistKeyInCsp = true; //密钥要保存起来
//rsaSend.Clear();
rsaReceive.PersistKeyInCsp = true;
//rsaReceive.Clear();

在上面的代码中，我们使用 CspParameters 将密钥保存起来，ToXmlString 和 FromXmlString 将接收方的公钥告诉给发送方。