feat(api): add --key parameter for demuxing

README.md

@@ -97,6 +97,8 @@ Several options are available for most of the commands :
 - `--audio-format` and `--video-format` can be used to select codecs. If at least one option is chosen, **the merging engine is automatically changed to FFMPEG**.
 - `--audio-lang` allow to specify audio track language in the output, allowed values are `[chi,eng,jpn,kor]`
 
+For demuxing, a key can be supplied to decrypt the USM file using either the parameter `--key <hex or number>` or `-b <4 lower bytes of key> -a <4 higher bytes of key>`.
+
 Maintenance commands and options:
 
 - `update` retrieves the latest `versions.json` file from the repository and checks if a new version has to be downloaded. It can take several optional parameters as follows :

src/Commands/DemuxCommand.cs

@@ -22,6 +22,7 @@ public DemuxCommand()
 
         CliOptions.Output.AddAlias("-o");
         AddOption(CliOptions.Output);
+        AddOption(CliOptions.HexKey);
         AddOption(CliOptions.Key1);
         AddOption(CliOptions.Key2);
         CliOptions.Subs.AddAlias("--subtitles");
@@ -43,6 +44,7 @@ public DemuxCommand()
         DemuxArgsOptionsBinder demuxArgsOptions = new DemuxArgsOptionsBinder(
             demuxInputArg,
             CliOptions.Output,
+            CliOptions.HexKey,
             CliOptions.Key1,
             CliOptions.Key2,
             CliOptions.MkvEngine,
@@ -65,13 +67,20 @@ private static void Execute(DemuxArgsOptions demuxArgsOptions)
         // Check given arguments and options
         if (!input.Exists)
             throw new ArgumentNullException($"Input path does not exist: {input.FullName}");
+
         DirectoryInfo output = demuxArgsOptions.output;
         if (!output.Exists)
             output.Create();
 
         byte[] key1 = demuxArgsOptions.key1 ?? Array.Empty<byte>();
         byte[] key2 = demuxArgsOptions.key2 ?? Array.Empty<byte>();
 
+        if (demuxArgsOptions.hexKey != null)
+        {
+            key1 = demuxArgsOptions.hexKey[..4];
+            key2 = demuxArgsOptions.hexKey[4..];
+        }
+
         bool merge = demuxArgsOptions.merge;
         bool includeSubs = demuxArgsOptions.subs;
         bool noCleanup = demuxArgsOptions.noCleanup;

src/Demuxer.cs

@@ -167,9 +167,9 @@ DirectoryInfo output
             Dictionary<string, List<string>> filePaths = usmFile.Demux(true, true, output.FullName); // TODO: Return file list for easier parsing
 
             if (!filePaths.TryGetValue("hca", out List<string> hcaPaths))
-                throw new Exception("No HCA files could be demuxed...");
+                Console.WriteLine("No HCA files have been demuxed...");
 
-            Task[] decodingTasks = new Task[hcaPaths.Count];
+            Task[] decodingTasks = new Task[(hcaPaths?.Count) ?? 0];
             for (int i = 0; i < decodingTasks.Length; i++)
             {
                 int j = i;

src/Parameters.cs

@@ -7,6 +7,7 @@ internal sealed class DemuxArgsOptions
     {
         public required FileSystemInfo input;
         public required DirectoryInfo output;
+        public byte[]? hexKey;
         public byte[]? key1;
         public byte[]? key2;
         public bool merge;
@@ -21,6 +22,7 @@ internal sealed class DemuxArgsOptions
     internal sealed class DemuxArgsOptionsBinder(
         Argument<FileSystemInfo> inputArg,
         Option<DirectoryInfo> outputOption,
+        Option<byte[]> hexKeyOption,
         Option<byte[]> key1Option,
         Option<byte[]> key2Option,
         Option<string> mkvEngineOption,
@@ -34,6 +36,7 @@ Option<string> audioLangOption
     {
         private Argument<FileSystemInfo> InputArg { get; } = inputArg;
         private Option<DirectoryInfo> OutputOption { get; } = outputOption;
+        private Option<byte[]> HexKeyOption { get; } = hexKeyOption;
         private Option<byte[]> Key1Option { get; } = key1Option;
         private Option<byte[]> Key2Option { get; } = key2Option;
         private Option<string> MkvEngineOption { get; } = mkvEngineOption;
@@ -51,6 +54,7 @@ protected override DemuxArgsOptions GetBoundValue(BindingContext bindingContext)
                 output =
                     bindingContext.ParseResult.GetValueForOption(OutputOption)
                     ?? new DirectoryInfo("./output"),
+                hexKey = bindingContext.ParseResult.GetValueForOption(HexKeyOption),
                 key1 = bindingContext.ParseResult.GetValueForOption(Key1Option),
                 key2 = bindingContext.ParseResult.GetValueForOption(Key2Option),
                 subs = bindingContext.ParseResult.GetValueForOption(SubsOption),

src/Utils/CliOptions.cs

@@ -1,3 +1,4 @@
+using System.Buffers.Binary;
 using System.CommandLine;
 
 namespace GICutscenes;
@@ -10,6 +11,31 @@ public static class CliOptions
         getDefaultValue: () => new DirectoryInfo("./output")
     );
 
+    public static Option<byte[]> HexKey = new Option<byte[]>(
+        name: "--key",
+        description: "USM encryption key (hexadecimal and number format are supported). Overrides options '-a' and '-b'",
+        parseArgument: result =>
+        {
+            string strKey = result.Tokens.Single().Value;
+            // If number only || If hex (0x before or letters A-F)
+            if (
+                ulong.TryParse(strKey, out ulong numKey)
+                || ulong.TryParse(
+                    strKey.StartsWith("0x") ? strKey.Substring(2) : strKey,
+                    System.Globalization.NumberStyles.HexNumber,
+                    null,
+                    out numKey
+                )
+            )
+            {
+                byte[] byteKey = new byte[8];
+                BitConverter.GetBytes(numKey).CopyTo(byteKey, 0);
+                return byteKey;
+            }
+            throw new ArgumentException("Argument --key <key> does not have the right format");
+        }
+    );
+
     public static Option<byte[]> Key1 = new Option<byte[]>(
         name: "-a",
         description: "4 lower bytes of the key (hex format)",