Commercial Application! writeup

comapp.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace commercial_app
{
	class Program
	{
		static void Main(string[] args)
		{
			var cipher = StringToByteArray("29a002d9340fc4bd54492f327269f3e051619b889dc8da723e135ce486965d84");
			var key = StringToByteArray("37eaae0141f1a3adf8a1dee655853714");
			var iv = Encoding.UTF8.GetBytes("a5efdbd57b84ca36");
			var serial = DecryptDataAES(cipher, key, iv);
			foreach(var d in Encoding.UTF8.GetBytes(serial))
			{
				Console.Write(Convert.ToString(d, 16));
				Console.Write(" ");
			}
			Console.WriteLine("\nEncode test");
			var encoded = EncryptDataAES(Encoding.UTF8.GetBytes(serial), key, iv);
			foreach (var d in cipher)
			{
				Console.Write(Convert.ToString(d, 16));
			}
			Console.WriteLine("");
			foreach (var d in encoded)
			{
				Console.Write(Convert.ToString(d, 16));
			}
			Console.WriteLine("");
			Console.WriteLine(serial);
		}

		//この辺
		// http://stackoverflow.com/questions/10424334/encryption-in-net-and-decryption-in-android-throws-badpaddingexception-pad-blo
		public static byte[] EncryptDataAES(byte[] toEncrypt, byte[] key, byte[] iv)
		{
			byte[] encryptedData;
			

			using (SymmetricAlgorithm aes = SymmetricAlgorithm.Create())
			{
				aes.Mode = CipherMode.CBC;
				aes.BlockSize = 128;
				aes.KeySize = 128;
				aes.Key = key;
				aes.IV = iv;
				aes.Padding = PaddingMode.PKCS7;
				ICryptoTransform encryptor = aes.CreateEncryptor();
				using (MemoryStream mStream = new MemoryStream())
				{
					using (CryptoStream cStream = new CryptoStream(mStream, encryptor, CryptoStreamMode.Write))
					{
						cStream.Write(toEncrypt, 0, toEncrypt.Length);
						cStream.FlushFinalBlock();
						encryptedData = mStream.ToArray();
					}
				}
			}
			return encryptedData;
		}

		public static string DecryptDataAES(byte[] cipherText, byte[] key, byte[] iv)
		{
			string plaintext = null;

			using (var aes = new AesManaged())
			{
				
				aes.BlockSize = 128;
				aes.KeySize = 128;
				aes.Padding = PaddingMode.PKCS7;
				aes.Key = key;
				aes.IV = iv;

				ICryptoTransform decryptor = aes.CreateDecryptor(aes.Key, aes.IV);

				// Create the streams used for decryption. 
				using (MemoryStream msDecrypt = new MemoryStream(cipherText))
				{
					using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
					{
						using (StreamReader srDecrypt = new StreamReader(csDecrypt))
						{
							plaintext = srDecrypt.ReadToEnd();
						}
					}
				}

			}

			return plaintext;
		}
		public static byte[] StringToByteArray(String hex)
		{
			int NumberChars = hex.Length / 2;
			byte[] bytes = new byte[NumberChars];
			using (var sr = new StringReader(hex))
			{
				for (int i = 0; i < NumberChars; i++)
					bytes[i] =
					  Convert.ToByte(new string(new char[2] { (char)sr.Read(), (char)sr.Read() }), 16);
			}
			return bytes;
		}
	}


}