v0.90.10

AssetStudio/Crypto/BlkUtils.cs

@@ -1,5 +1,7 @@
 using System;
 using System.Buffers.Binary;
+using System.Collections.Generic;
+using System.Text;
 
 namespace AssetStudio
 {
@@ -8,16 +10,20 @@ namespace AssetStudio
         private const int DataOffset = 0x2A;
         private const int KeySize = 0x1000;
         private const int SeedBlockSize = 0x800;
+        private const int BufferSize = 0x10000;
 
         public static XORStream Decrypt(FileReader reader, Blk blk)
         {
             reader.Endian = EndianType.LittleEndian;
 
             var signature = reader.ReadStringToNull();
+            Logger.Verbose($"Signature: {signature}");
             var count = reader.ReadInt32();
+            Logger.Verbose($"Key size: {count}");
             var key = reader.ReadBytes(count);
             reader.Position += count;
             var seedSize = Math.Min(reader.ReadInt16(), blk.SBox.IsNullOrEmpty() ? SeedBlockSize : SeedBlockSize * 2);
+            Logger.Verbose($"Seed size: 0x{seedSize:X8}");
 
             if (!blk.SBox.IsNullOrEmpty() && blk.Type.IsGI())
             {
@@ -47,6 +53,8 @@ namespace AssetStudio
             var keyHigh = BinaryPrimitives.ReadUInt64LittleEndian(key.AsSpan(8, 8));
             var seed = keyLow ^ keyHigh ^ keySeed ^ blk.InitSeed;
 
+            Logger.Verbose($"Seed: 0x{seed:X8}");
+
             var mt64 = new MT19937_64(seed);
             var xorpad = new byte[KeySize];
             for (int i = 0; i < KeySize; i += 8)
@@ -56,5 +64,48 @@ namespace AssetStudio
 
             return new XORStream(reader.BaseStream, DataOffset, xorpad);
         }
+
+        public static IEnumerable<long> GetOffsets(this XORStream stream, string path)
+        {
+            if (AssetsHelper.TryGet(path, out var offsets))
+            {
+                foreach(var offset in offsets)
+                {
+                    stream.Offset = offset;
+                    yield return offset;
+                }
+            }
+            else
+            {
+                using var reader = new FileReader(path, stream, true);
+                var signature = reader.FileType switch
+                {
+                    FileType.BundleFile => "UnityFS\x00",
+                    FileType.Mhy0File => "mhy0",
+                    _ => throw new InvalidOperationException()
+                };
+
+                Logger.Verbose($"Prased signature: {signature}");
+
+                var signatureBytes = Encoding.UTF8.GetBytes(signature);
+                var buffer = BigArrayPool<byte>.Shared.Rent(BufferSize);
+                while (stream.Remaining > 0)
+                {
+                    var index = 0;
+                    var absOffset = stream.AbsolutePosition;
+                    var read = stream.Read(buffer);
+                    while (index < read)
+                    {
+                        index = buffer.AsSpan(0, read).Search(signatureBytes, index);
+                        if (index == -1) break;
+                        var offset = absOffset + index;
+                        stream.Offset = offset;
+                        yield return offset;
+                        index++;
+                    }
+                }
+                BigArrayPool<byte>.Shared.Return(buffer);
+            }
+        }
     }
 }