diff --git a/src/main/java/net/runelite/cache/fs/IndexEntry.java b/src/main/java/net/runelite/cache/fs/IndexEntry.java
new file mode 100644
index 0000000000..56215c7919
--- /dev/null
+++ b/src/main/java/net/runelite/cache/fs/IndexEntry.java
@@ -0,0 +1,79 @@
+package net.runelite.cache.fs;
+
+import java.util.Objects;
+
+public class IndexEntry
+{
+	private IndexFile indexFile;
+	private int id, sector, length;
+
+	public IndexEntry(IndexFile indexFile, int id, int sector, int length)
+	{
+		this.indexFile = indexFile;
+		this.id = id;
+		this.sector = sector;
+		this.length = length;
+	}
+
+	public IndexFile getIndexFile()
+	{
+		return indexFile;
+	}
+
+	public int getId()
+	{
+		return id;
+	}
+
+	public int getSector()
+	{
+		return sector;
+	}
+
+	public int getLength()
+	{
+		return length;
+	}
+
+	@Override
+	public int hashCode()
+	{
+		int hash = 7;
+		hash = 19 * hash + Objects.hashCode(this.indexFile);
+		hash = 19 * hash + this.id;
+		hash = 19 * hash + this.sector;
+		hash = 19 * hash + this.length;
+		return hash;
+	}
+
+	@Override
+	public boolean equals(Object obj)
+	{
+		if (obj == null)
+		{
+			return false;
+		}
+		if (getClass() != obj.getClass())
+		{
+			return false;
+		}
+		final IndexEntry other = (IndexEntry) obj;
+		if (!Objects.equals(this.indexFile, other.indexFile))
+		{
+			return false;
+		}
+		if (this.id != other.id)
+		{
+			return false;
+		}
+		if (this.sector != other.sector)
+		{
+			return false;
+		}
+		if (this.length != other.length)
+		{
+			return false;
+		}
+		return true;
+	}
+}
diff --git a/src/main/java/net/runelite/cache/fs/IndexFile.java b/src/main/java/net/runelite/cache/fs/IndexFile.java
new file mode 100644
index 0000000000..4bbb6d6890
--- /dev/null
+++ b/src/main/java/net/runelite/cache/fs/IndexFile.java
@@ -0,0 +1,57 @@
+package net.runelite.cache.fs;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class IndexFile
+{
+	private static final Logger logger = LoggerFactory.getLogger(IndexFile.class);
+	private static final int INDEX_ENTRY_LEN = 6;
+	
+	private int indexFileId;
+	private RandomAccessFile idx;
+	private final byte[] buffer = new byte[6];
+	
+	public IndexFile(int indexFileId, File file) throws FileNotFoundException
+	{
+		this.indexFileId = indexFileId;
+		this.idx = new RandomAccessFile(file, "rw");
+	}
+	
+	public synchronized void write(IndexEntry entry) throws IOException
+	{
+		idx.seek(entry.getId() * INDEX_ENTRY_LEN);
+		
+		buffer[0] = (byte) (entry.getLength() >> 16);
+		buffer[1] = (byte) (entry.getLength() >> 8);
+		buffer[2] = (byte) entry.getLength();
+		
+		buffer[3] = (byte) (entry.getSector() >> 16);
+		buffer[4] = (byte) (entry.getSector() >> 8);
+		buffer[5] = (byte) entry.getSector();
+		
+		idx.write(buffer);
+	}
+	
+	public synchronized IndexEntry read(int id) throws IOException
+	{
+		idx.seek(id * INDEX_ENTRY_LEN);
+		int i = idx.read(buffer);
+		if (i != INDEX_ENTRY_LEN)
+			logger.warn("short read");
+		
+		int length = ((buffer[0] & 0xFF) << 16) | ((buffer[1] & 0xFF) << 8) | (buffer[2] & 0xFF);
+		int sector = ((buffer[3] & 0xFF) << 16) | ((buffer[4] & 0xFF) << 8) | (buffer[5] & 0xFF);
+		
+		return new IndexEntry(this, id, sector, length);
+	}
+	
+	public synchronized int getIndexCount() throws IOException
+	{
+		return (int)(idx.length() / INDEX_ENTRY_LEN);
+	}
+}
diff --git a/src/test/java/net/runelite/cache/fs/IndexFileTest.java b/src/test/java/net/runelite/cache/fs/IndexFileTest.java
new file mode 100644
index 0000000000..5cce282d6c
--- /dev/null
+++ b/src/test/java/net/runelite/cache/fs/IndexFileTest.java
@@ -0,0 +1,20 @@
+package net.runelite.cache.fs;
+
+import java.io.File;
+import java.io.IOException;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class IndexFileTest
+{
+	@Test
+	public void test1() throws IOException
+	{
+		File file = new File("d:/rs/07/test/test.dat");
+		IndexFile index = new IndexFile(5, file);
+		IndexEntry entry = new IndexEntry(index, 7, 8, 9);
+		index.write(entry);
+		IndexEntry entry2 = index.read(7);
+		Assert.assertEquals(entry, entry2);
+	}
+}