Helper methods for decrypting Cipher (hex encoded string) given the IV and key for the Find Treasure Game using C#

.cs

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

namespace FindTreasureApp.Services
{
    public class Decryption
    {
        const string keyString = "57067125438768260656188878670043";
        const string ivString = "5706712543876826";
        
        /// <summary>
        /// Decrypt the Ciper
        /// </summary>
        /// <param name="cipherId">The hex encoded string</param>
        /// <param name="rounds">The number of times string was encoded</param>
        public static string DecryptCiper(string cipherId, int rounds)
        {
            string decryptedString = cipherId;
            
            while(rounds > 0)
            {
                byte[] cipherByte = ToByteArray(decryptedString);
                decryptedString = AES_HEX_Decrypt_CBC(cipherByte);
                rounds--;
            }

            return decryptedString;
        }

        static byte[] ToByteArray(string hexString)
        {
            byte[] retval = new byte[hexString.Length / 2];
            for (int i = 0; i < hexString.Length; i += 2)
                retval[i / 2] = Convert.ToByte(hexString.Substring(i, 2), 16);
            return retval;
        }

        static string AES_HEX_Decrypt_CBC(byte[] cipherData)
        {
            byte[] key = Encoding.UTF8.GetBytes(keyString);
            byte[] iv = Encoding.UTF8.GetBytes(ivString);

            try
            {
                using (var rijndaelManaged =
                new RijndaelManaged { Key = key, IV = iv, Mode = CipherMode.CBC })
                using (var memoryStream =
                new MemoryStream(cipherData))
                using (var cryptoStream =
                new CryptoStream(memoryStream,
                rijndaelManaged.CreateDecryptor(key, iv),
                CryptoStreamMode.Read))
                {
                    return new StreamReader(cryptoStream).ReadToEnd();
                }
            }
            catch (CryptographicException e)
            {
                Console.WriteLine("A Cryptographic error occurred: {0}", e.Message);
                return null;
            }
            
        }
    }

}

Updated, thanks.

…

On Fri, Oct 30, 2020 at 2:06 PM Ikechi Michael ***@***.***> wrote: ***@***.**** commented on this gist. ------------------------------ Line 24 should be: byte[] cipherByte = ToByteArray(decryptedString); There's no cipher variable in that scope. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <https://gist.github.com/6284aa0db17d50834490321211b97da4#gistcomment-3510247>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACUSEDCEAKM5WYJFLE5PUC3SNK25BANCNFSM4TE6NZAQ> .