// (c) 2006 Richard Grimes
// www.grimes.demon.co.uk

using System;
using System.Security.Cryptography;
using System.Security.Cryptography.Xml;
using System.Xml;
using System.IO;

class App
{
   // parameters: e|d infile outfile passphrase
   static void Main(string[] args)
   {
      if (args.Length < 4)
      {
         Console.WriteLine("Usage: symm e|d infile outfile passphrase");
         return;
      }

      bool bEncrypt = (args[0][0] == 'e');
      string infile = args[1];
      if (!File.Exists(infile))
      {
         Console.WriteLine("{0} does not exist", infile);
         return;
      }

      string outfile = args[2];
      if (File.Exists(outfile))
      {
         File.Delete(outfile);
      }

      string passphrase = args[3];

      Rijndael key = new RijndaelManaged();
      PasswordDeriveBytes pdb = new PasswordDeriveBytes(passphrase, null);
      key.Key = pdb.GetBytes(key.KeySize / 8);

      if (bEncrypt)
      {
         Encrypt(infile, outfile, key);
      }
      else
      {
         Decrypt(infile, outfile, key);
      }
   }
   static void Encrypt(string infile, string outfile, SymmetricAlgorithm key)
   {
      XmlDocument doc = new XmlDocument();
      doc.Load(infile);
      XmlElement elem = (XmlElement)doc.GetElementsByTagName("CreditCard")[0];
      EncryptedXml encXml = new EncryptedXml();
      byte[] enc = encXml.EncryptData(elem, key, false);
      EncryptedData ed = new EncryptedData();
      ed.Type = EncryptedXml.XmlEncElementUrl;
      ed.EncryptionMethod = new EncryptionMethod(EncryptedXml.XmlEncAES256Url);
      ed.CipherData.CipherValue = enc;
      EncryptedXml.ReplaceElement(elem, ed, false);
      doc.Save(outfile);
   }
   static void Decrypt(string infile, string outfile, SymmetricAlgorithm key)
   {
   }
}