C# RSA分段加解密实现方法详解

internal static string GetEncryptedMsg(string xml)
{
  byte[] encryptedData;
  using (var rsa = GetPublicKey(Configs.PublicKeyFilePath))
  {
    var plainData = Encoding.UTF8.GetBytes(xml);
    using (var plaiStream = new MemoryStream(plainData))
    {
      using (var crypStream = new MemoryStream())
      {
        var offSet = 0;
        var inputLen = plainData.Length;
        for (var i = 0; inputLen - offSet > 0; offSet = i*244)
        {
          if (inputLen - offSet > 244)
          {
            var buffer = new Byte[244];
            plaiStream.Read(buffer, 0, 244);
            var cryptograph = rsa.Encrypt(buffer, false);
            crypStream.Write(cryptograph, 0, cryptograph.Length);
          }
          else
          {
            var buffer = new Byte[inputLen - offSet];
            plaiStream.Read(buffer, 0, inputLen - offSet);
            var cryptograph = rsa.Encrypt(buffer, false);
            crypStream.Write(cryptograph, 0, cryptograph.Length);
          }
          ++i;
        }
        crypStream.Position = 0;
        encryptedData = crypStream.ToBytes();
      }
    }
  }
  return BitConverter.ToString(encryptedData).Replace("-", string.Empty);
}
internal static byte[] GetDecryptedMsg(byte[] encryptedBytes)
{
  using (var rsa = GetPrivateKey(Configs.PrivateKeyFilePath, Configs.PrivateKeyPasswd))
  {
    byte[] decryptedData;
    using (var plaiStream = new MemoryStream(encryptedBytes))
    {
      using (var decrypStream = new MemoryStream())
      {
        var offSet = 0;
        var inputLen = encryptedBytes.Length;
        for (var i = 0; inputLen - offSet > 0; offSet = i * 256)
        {
          if (inputLen - offSet > 256)
          {
            var buffer = new Byte[256];
            plaiStream.Read(buffer, 0, 256);
            var decrypData = rsa.Decrypt(buffer, false);
            decrypStream.Write(decrypData, 0, decrypData.Length);
          }
          else
          {
            var buffer = new Byte[inputLen - offSet];
            plaiStream.Read(buffer, 0, inputLen - offSet);
            var decrypData = rsa.Decrypt(buffer, false);
            decrypStream.Write(decrypData, 0, decrypData.Length);
          }
          ++i;
        }
        decrypStream.Position = 0;
        decryptedData = decrypStream.ToBytes();
      }
    }
    return decryptedData;
  }
}