少见的C# RSA算法

 static void Main(string[] args) {
  RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();  string xmlPrivateKey = rsa.ToXmlString(true);//XML密钥
  string pemPrivateKey = Xml2PemPrivate(xmlPrivateKey, "F:/privatePEM.txt");//PEM密钥

  string xmlPublicKey = rsa.ToXmlString(false);//XML公钥
  string pemPublicKey = Xml2PemPublic(xmlPublicKey, "F:/publicPEM.txt");//PEM密钥
 } /// <summary>
 /// XML格式公钥转PEM格式公钥
 /// </summary>
 /// <param name="xml">XML格式的公钥</param>
 /// <param name="saveFile">保存文件的物理路径</param>
 public static string Xml2PemPublic(string xml, string saveFile) {  var rsa = new RSACryptoServiceProvider();
  rsa.FromXmlString(xml);  var p = rsa.ExportParameters(false);
  RsaKeyParameters key = new RsaKeyParameters(false, new BigInteger(1, p.Modulus), new BigInteger(1, p.Exponent));  using (var sw = new StreamWriter(saveFile))
  {  var pemWriter = new Org.BouncyCastle.OpenSsl.PemWriter(sw);
  pemWriter.WriteObject(key);
  }

  SubjectPublicKeyInfo publicKeyInfo = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(key);  byte[] serializedPublicBytes = publicKeyInfo.ToAsn1Object().GetDerEncoded();  string publicKey = Convert.ToBase64String(serializedPublicBytes);  return Format(publicKey, 1);
 } /// <summary>
 /// XML格式私钥转PEM
 /// </summary>
 /// <param name="xml">XML格式私钥</param>
 /// <param name="saveFile">保存文件的物理路径</param>
 public static string Xml2PemPrivate(string xml, string saveFile) {  var rsa = new RSACryptoServiceProvider();
  rsa.FromXmlString(xml);  var p = rsa.ExportParameters(true);  var key = new RsaPrivateCrtKeyParameters(  new BigInteger(1, p.Modulus), new BigInteger(1, p.Exponent), new BigInteger(1, p.D),  new BigInteger(1, p.P), new BigInteger(1, p.Q), new BigInteger(1, p.DP), new BigInteger(1, p.DQ),  new BigInteger(1, p.InverseQ));  using (var sw = new StreamWriter(saveFile))
  {  var pemWriter = new Org.BouncyCastle.OpenSsl.PemWriter(sw);
  pemWriter.WriteObject(key);
  }

  PrivateKeyInfo privateKeyInfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(key);  byte[] serializedPrivateBytes = privateKeyInfo.ToAsn1Object().GetEncoded();  string privateKey = Convert.ToBase64String(serializedPrivateBytes);  return Format(privateKey, 2);
 } /// <summary>
 /// 格式化公钥/私钥
 /// </summary>
 /// <param name="key">生成的公钥/私钥</param>
 /// <param name="type">1:公钥 2:私钥</param>
 /// <returns>PEM格式的公钥/私钥</returns>
 public static string Format(string key, int type) {  string result = string.Empty;  int length = key.Length / 64;  for (int i = 0; i < length; i++)
  {  int start = i * 64;
  result = result + key.Substring(start, 64) + "\r\n";
  }

  result = result + key.Substring(length * 64);  if (type == 1)
  {
  result = result.Insert(0, "-----BEGIN PUBLIC KEY-----\r\n");
  result += "\r\n-----END PUBLIC KEY-----";
  }  if (type == 2)
  {
  result = result.Insert(0, "-----BEGIN PRIVATE KEY-----\r\n");
  result += "\r\n-----END PRIVATE KEY-----";
  }  return result;
 }