Read save files from SD card

LibHac/Nax0.cs

@@ -21,11 +21,10 @@ namespace LibHac
             stream.Position = 0;
             KeepOpen = keepOpen;
             ReadHeader(stream);
-            DeriveKeys(keyset, sdPath);
+            DeriveKeys(keyset, sdPath, stream);
-            ValidateKeys(keyset, stream);
 
             stream.Position = 0x4000;
-            var xts = XtsAes128.Create(Keys[0], Keys[1]);
+            Xts xts = XtsAes128.Create(Keys[0], Keys[1]);
             Stream = new RandomAccessSectorStream(new XtsSectorStream(stream, xts, 0x4000, 0x4000), keepOpen);
         }
 
@@ -44,38 +43,45 @@ namespace LibHac
             Length = reader.ReadInt64();
         }
 
-        private void DeriveKeys(Keyset keyset, string sdPath)
+        private void DeriveKeys(Keyset keyset, string sdPath, Stream stream)
         {
+            stream.Position = 0x20;
+            var validationHashKey = new byte[0x60];
+            stream.Read(validationHashKey, 0, 0x60);
+
+            // Try both the NCA and save key sources and pick the one that works
             for (int k = 0; k < 2; k++)
             {
                 var naxSpecificKeys = Util.CreateJaggedArray<byte[][]>(2, 0x10);
                 var hashKey = new byte[0x10];
                 Array.Copy(keyset.sd_card_keys[k], hashKey, 0x10);
 
+                // Use the sd path to generate the kek for this NAX0
                 var hash = new HMACSHA256(hashKey);
-                var sdPathBytes = Encoding.ASCII.GetBytes(sdPath);
+                byte[] sdPathBytes = Encoding.ASCII.GetBytes(sdPath);
-                var checksum = hash.ComputeHash(sdPathBytes, 0, sdPathBytes.Length);
+                byte[] checksum = hash.ComputeHash(sdPathBytes, 0, sdPathBytes.Length);
                 Array.Copy(checksum, 0, naxSpecificKeys[0], 0, 0x10);
                 Array.Copy(checksum, 0x10, naxSpecificKeys[1], 0, 0x10);
 
+                // Decrypt this NAX0's keys
                 Crypto.DecryptEcb(naxSpecificKeys[0], EncKeys[0], Keys[0], 0x10);
                 Crypto.DecryptEcb(naxSpecificKeys[1], EncKeys[1], Keys[1], 0x10);
+
+                // Copy the decrypted keys into the NAX0 header and use that for the HMAC key
+                // for validating that the keys are correct
+                Array.Copy(Keys[0], 0, validationHashKey, 8, 0x10);
+                Array.Copy(Keys[1], 0, validationHashKey, 0x18, 0x10);
+
+                var validationHash = new HMACSHA256(validationHashKey);
+                byte[] validationMac = validationHash.ComputeHash(keyset.sd_card_keys[k], 0x10, 0x10);
+
+                if (Util.ArraysEqual(Hmac, validationMac))
+                {
+                    return;
+                }
             }
-        }
 
-        private void ValidateKeys(Keyset keyset, Stream stream)
+            throw new ArgumentException("NAX0 key derivation failed.");
-        {
-            stream.Position = 0x20;
-            var hashKey = new byte[0x60];
-            stream.Read(hashKey, 0, 0x60);
-            Array.Copy(Keys[0], 0, hashKey, 8, 0x10);
-            Array.Copy(Keys[1], 0, hashKey, 0x18, 0x10);
-
-            var hash = new HMACSHA256(hashKey);
-            var validationMac = hash.ComputeHash(keyset.sd_card_keys[1], 0x10, 0x10);
-            var isValid = Util.ArraysEqual(Hmac, validationMac);
-
-            if (!isValid) throw new ArgumentException("NAX0 key derivation failed.");
         }
 
         public void Dispose()

LibHac/SwitchFs.cs

@@ -13,8 +13,10 @@ namespace LibHac
         public Keyset Keyset { get; }
         public IFileSystem Fs { get; }
         public string ContentsDir { get; }
+        public string SaveDir { get; }
 
         public Dictionary<string, Nca> Ncas { get; } = new Dictionary<string, Nca>(StringComparer.OrdinalIgnoreCase);
+        public Dictionary<string, Savefile.Savefile> Saves { get; } = new Dictionary<string, Savefile.Savefile>(StringComparer.OrdinalIgnoreCase);
         public Dictionary<ulong, Title> Titles { get; } = new Dictionary<ulong, Title>();
         public Dictionary<ulong, Application> Applications { get; } = new Dictionary<ulong, Application>();
 
@@ -26,10 +28,19 @@ namespace LibHac
             if (fs.DirectoryExists("Nintendo"))
             {
                 ContentsDir = fs.GetFullPath(Path.Combine("Nintendo", "Contents"));
+                SaveDir = fs.GetFullPath(Path.Combine("Nintendo", "save"));
             }
-            else if (fs.DirectoryExists("Contents"))
+            else
             {
-                ContentsDir = fs.GetFullPath("Contents");
+                if (fs.DirectoryExists("Contents"))
+                {
+                    ContentsDir = fs.GetFullPath("Contents");
+                }
+
+                if (fs.DirectoryExists("save"))
+                {
+                    SaveDir = fs.GetFullPath("save");
+                }
             }
 
             if (ContentsDir == null)
@@ -37,6 +48,7 @@ namespace LibHac
                 throw new DirectoryNotFoundException("Could not find \"Contents\" directory");
             }
 
+            OpenAllSaves();
             OpenAllNcas();
             ReadTitles();
             ReadControls();
@@ -87,6 +99,35 @@ namespace LibHac
             }
         }
 
+        private void OpenAllSaves()
+        {
+            string[] files = Fs.GetFileSystemEntries(SaveDir, "*");
+
+            foreach (string file in files)
+            {
+                Savefile.Savefile save = null;
+                string saveName = Path.GetFileNameWithoutExtension(file);
+
+                try
+                {
+                    Stream stream = Fs.OpenFile(file, FileMode.Open);
+
+                    string sdPath = "/" + Util.GetRelativePath(file, SaveDir).Replace('\\', '/');
+                    var nax0 = new Nax0(Keyset, stream, sdPath, false);
+                    save = new Savefile.Savefile(nax0.Stream);
+                }
+                catch (Exception ex)
+                {
+                    Console.WriteLine($"{ex.Message} {file}");
+                }
+
+                if (save != null && saveName != null)
+                {
+                    Saves[saveName] = save;
+                }
+            }
+        }
+
         private void ReadTitles()
         {
             foreach (var nca in Ncas.Values.Where(x => x.Header.ContentType == ContentType.Meta))
@@ -126,7 +167,7 @@ namespace LibHac
                     }
                 }
 
-                Titles.Add(title.Id, title);
+                Titles[title.Id] = title;
             }
         }
 

README.md

@@ -56,6 +56,7 @@ Switch FS options:
   --exefsdir <dir>     Specify ExeFS directory path. (--title must be specified)
   --romfs <file>       Specify RomFS directory path. (--title must be specified)
   --romfsdir <dir>     Specify RomFS directory path. (--title must be specified)
+  --savedir <dir>      Specify save file directory path.
 Savefile options:
   --outdir <dir>       Specify directory path to save contents to.
   --debugoutdir <dir>  Specify directory path to save intermediate data to for debugging.

hactoolnet/CliParser.cs

@@ -29,6 +29,7 @@ namespace hactoolnet
             new CliOption("romfs", 1, (o, a) => o.RomfsOut = a[0]),
             new CliOption("romfsdir", 1, (o, a) => o.RomfsOutDir = a[0]),
             new CliOption("debugoutdir", 1, (o, a) => o.DebugOutDir = a[0]),
+            new CliOption("savedir", 1, (o, a) => o.SaveOutDir = a[0]),
             new CliOption("outdir", 1, (o, a) => o.OutDir = a[0]),
             new CliOption("nspout", 1, (o, a) => o.NspOut = a[0]),
             new CliOption("sdseed", 1, (o, a) => o.SdSeed = a[0]),
@@ -184,6 +185,7 @@ namespace hactoolnet
             sb.AppendLine("  --exefsdir <dir>     Specify ExeFS directory path. (--title must be specified)");
             sb.AppendLine("  --romfs <file>       Specify RomFS directory path. (--title must be specified)");
             sb.AppendLine("  --romfsdir <dir>     Specify RomFS directory path. (--title must be specified)");
+            sb.AppendLine("  --savedir <dir>      Specify save file directory path.");
             sb.AppendLine("Savefile options:");
             sb.AppendLine("  --outdir <dir>       Specify directory path to save contents to.");
             sb.AppendLine("  --debugoutdir <dir>  Specify directory path to save intermediate data to for debugging.");

hactoolnet/Options.cs

@@ -19,6 +19,7 @@ namespace hactoolnet
         public string RomfsOut;
         public string RomfsOutDir;
         public string DebugOutDir;
+        public string SaveOutDir;
         public string OutDir;
         public string SdSeed;
         public string NspOut;

hactoolnet/Program.cs

@@ -256,6 +256,11 @@ namespace hactoolnet
             {
                 CreateNsp(ctx, switchFs);
             }
+
+            if (ctx.Options.SaveOutDir != null)
+            {
+                ExportSdSaves(ctx, switchFs);
+            }
         }
 
         private static void ProcessXci(Context ctx)
@@ -650,6 +655,15 @@ namespace hactoolnet
 
             return sb.ToString();
         }
+
+        private static void ExportSdSaves(Context ctx, SwitchFs switchFs)
+        {
+            foreach (var save in switchFs.Saves)
+            {
+                var outDir = Path.Combine(ctx.Options.SaveOutDir, save.Key);
+                save.Value.Extract(outDir, ctx.Logger);
+            }
+        }
     }
 }