Done

CipherForge/Program.cs

@@ -1 +1,91 @@
-Console.WriteLine("Hello, World!");
+namespace CipherForge;
+
+public static class Program
+{
+    public static void Main(string[] args)
+    {
+        Console.WriteLine("Please choose an option by typing the corresponding number:");
+        Console.WriteLine("1: Convert an AES key to the keychain format");
+        Console.WriteLine("2: Convert a keychain to an AES key");
+        Console.Write("Enter your choice (1 or 2): ");
+
+        if (!int.TryParse(Console.ReadLine(), out var choice) || (choice != 1 && choice != 2))
+        {
+            Console.WriteLine("Invalid input. Please restart the program and enter either 1 or 2.");
+            return;
+        }
+
+        var result = string.Empty;
+
+        switch (choice)
+        {
+            case 1:
+            {
+                Console.WriteLine("Please enter the AES Key");
+                var aes = Console.ReadLine()?.SubstringAfter("0x");
+
+                if (string.IsNullOrEmpty(aes))
+                {
+                    Console.WriteLine("Invalid AES Key. Please restart the program");
+                    return;
+                }
+
+                Console.WriteLine("Please enter the GUID");
+                var guid = Console.ReadLine()?.Replace("-", string.Empty);
+
+                if (string.IsNullOrEmpty(guid))
+                {
+                    Console.WriteLine("Invalid GUID. Please restart the program");
+                    return;
+                }
+
+                result = ConvertHexToKeychain(aes, guid);
+                break;
+            }
+            case 2:
+            {
+                Console.WriteLine("Please enter the keychain");
+                var keyChain = Console.ReadLine()?.SubstringAfter(":");
+
+                if (string.IsNullOrEmpty(keyChain))
+                {
+                    Console.WriteLine("Invalid keychain. Please restart the program");
+                    return;
+                }
+
+                result = ConvertKeychainToHex(keyChain);
+                break;
+            }
+        }
+
+        Console.WriteLine(result);
+    }
+
+    private static string ConvertHexToKeychain(string aes, string guid)
+    {
+        var length = aes.Length;
+        var bytes = new byte[length / 2];
+        for (var i = 0; i < length; i += 2)
+        {
+            bytes[i / 2] = Convert.ToByte(aes.Substring(i, 2), 16);
+        }
+
+        var base64String = Convert.ToBase64String(bytes);
+        return $"{guid}:{base64String}";
+    }
+
+    private static string ConvertKeychainToHex(string keyChain)
+    {
+        var bytes = Convert.FromBase64String(keyChain);
+        var aes = BitConverter.ToString(bytes).Replace("-", string.Empty);
+
+        return $"0x{aes}";
+    }
+
+    // https://github.com/FabianFG/CUE4Parse/blob/master/CUE4Parse/Utils/StringUtils.cs#L52-L57
+    private static string SubstringAfter(this string s, string delimiter, StringComparison comparisonType = StringComparison.Ordinal)
+    {
+        var index = s.IndexOf(delimiter, comparisonType);
+        return index == -1 ? s : s.Substring(index + delimiter.Length, s.Length - index - delimiter.Length);
+    }
+}