Fallout Shelter Objectives Fixer

using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;
using System.Text.RegularExpressions;

//{"objective":{"objectiveID":"EquipRandomWeapon","requirements":[{"requirementID":"r1","satisfied":false,"currentEquippedDwellers":0,"targetWeaponIDs":["MissileLauncher","MissileLauncher_Rusty","MissileLauncher_Enhanced","MissileLauncher_Hardened","MissileLauncher_Guided","MissileLauncher_MissLauncher"]}],"completed":false,"incrementLevel":1},"incLevel":6,"lottery":[false,true,true,true,true]}]}


public static class FalloutShelterDecrypt
{
    private const string initVector = "tu89geji340t89u2";
    private const string passPhrase = "UGxheWVy";
    private const int keysize = 256;


    private const string m_strObjetive_EquipMissileLauncher_NotComplete = "\"targetWeaponIDs\":[\"MissileLauncher\",\"MissileLauncher_Rusty\",\"MissileLauncher_Enhanced\",\"MissileLauncher_Hardened\",\"MissileLauncher_Guided\",\"MissileLauncher_MissLauncher\"]}],\"completed\":false,";
    private const string m_strObjetive_EquipMissileLauncher____Replaced = "\"targetWeaponIDs\":[\"Shotgun\"]}],\"completed\":true,";



    public static bool IsBase64String(this string s)
    {
        s = s.Trim();
        return (s.Length % 4 == 0) && Regex.IsMatch(s, @"^[a-zA-Z0-9\+/]*={0,3}$", RegexOptions.None);

    }

    public static bool IsObjectiveBug_EquipMissileLauncher(String strText)
    {
        return (strText.IndexOf(m_strObjetive_EquipMissileLauncher_NotComplete) != -1);
    }

    public static string Encrypt(string Text)
    {
        byte[] initVectorBytes = Encoding.UTF8.GetBytes(initVector);
        byte[] plainTextBytes = Encoding.UTF8.GetBytes(Text);
        Rfc2898DeriveBytes password = new Rfc2898DeriveBytes(passPhrase, initVectorBytes);
        byte[] keyBytes = password.GetBytes(keysize / 8);
        RijndaelManaged symmetricKey = new RijndaelManaged();
        symmetricKey.Mode = CipherMode.CBC;
        ICryptoTransform encryptor = symmetricKey.CreateEncryptor(keyBytes, initVectorBytes);
        MemoryStream memoryStream = new MemoryStream();
        CryptoStream cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write);
        cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
        cryptoStream.FlushFinalBlock();
        byte[] Encrypted = memoryStream.ToArray();
        memoryStream.Close();
        cryptoStream.Close();
        return Convert.ToBase64String(Encrypted);
    }

    public static string Decrypt(string EncryptedText)
    {
        byte[] initVectorBytes = Encoding.ASCII.GetBytes(initVector);
        byte[] DeEncryptedText = Convert.FromBase64String(EncryptedText);
        Rfc2898DeriveBytes password = new Rfc2898DeriveBytes(passPhrase, initVectorBytes);
        byte[] keyBytes = password.GetBytes(keysize / 8);
        RijndaelManaged symmetricKey = new RijndaelManaged();
        symmetricKey.Mode = CipherMode.CBC;
        ICryptoTransform decryptor = symmetricKey.CreateDecryptor(keyBytes, initVectorBytes);
        MemoryStream memoryStream = new MemoryStream(DeEncryptedText);
        CryptoStream cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read);
        byte[] plainTextBytes = new byte[DeEncryptedText.Length];
        int decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
        memoryStream.Close();
        cryptoStream.Close();
        return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
    }

    static void Main(string[] args)
    {
        if (args.Length < 1)
        {
            Console.WriteLine("Usage: FOSFixObjectives.exe input_file (or drag the save file onto this file)");
            Console.Read();
            return; //nothing to do.
        }

        String data = File.ReadAllText(args[0]);

        if (IsBase64String(data))
        {
            String decryptedData = Decrypt(data);
            int nQuestsCompleted = 0;
            while (IsObjectiveBug_EquipMissileLauncher(decryptedData))
            {
                decryptedData = decryptedData.Replace(m_strObjetive_EquipMissileLauncher_NotComplete, m_strObjetive_EquipMissileLauncher____Replaced);
                nQuestsCompleted++;
            }

            if (nQuestsCompleted > 0)
            {
                File.WriteAllText(args[0], Encrypt(decryptedData));
                Console.WriteLine("{0:D} Equip Missile Launcher Objective(s) Replaced.", nQuestsCompleted);
                Console.Read();
                return; //done.
            }
            else
            {
                Console.WriteLine("No \"Equip Missile Launcher Objective\" found to fix! If Objectives Still does not work, please submit your save file for investigation!");
                Console.Read();
                return; //done
            }
        }
        else
        {
            Console.WriteLine("not a valid Fallout Shelter Save File");
            Console.Read();
            return; //done
        }
    }
}