Add AesXtsFile creation and FileReader

src/LibHac/Crypto.cs

@@ -44,6 +44,21 @@ namespace LibHac
         public static void DecryptEcb(byte[] key, byte[] src, byte[] dest, int length) =>
             DecryptEcb(key, src, 0, dest, 0, length);
 
+        public static void EncryptEcb(byte[] key, byte[] src, int srcIndex, byte[] dest, int destIndex, int length)
+        {
+            using (Aes aes = Aes.Create())
+            {
+                if (aes == null) throw new CryptographicException("Unable to create AES object");
+                aes.Key = key;
+                aes.Mode = CipherMode.ECB;
+                aes.Padding = PaddingMode.None;
+                Array.Copy(aes.CreateEncryptor().TransformFinalBlock(src, srcIndex, length), 0, dest, destIndex, length);
+            }
+        }
+
+        public static void EncryptEcb(byte[] key, byte[] src, byte[] dest, int length) =>
+            EncryptEcb(key, src, 0, dest, 0, length);
+
         public static void DecryptCbc(byte[] key, byte[] iv, byte[] src, int srcIndex, byte[] dest, int destIndex, int length)
         {
             using (Aes aes = Aes.Create())

src/LibHac/IO/AesXtsDirectory.cs

@@ -46,9 +46,9 @@ namespace LibHac.IO
         {
             using (IFile file = BaseFileSystem.OpenFile(path, OpenMode.Read))
             {
-                var buffer = new byte[8];
+                var buffer = new byte[8]; 
 
-                file.Read(buffer, 0);
+                file.Read(buffer, 0x20);
                 if (BitConverter.ToUInt32(buffer, 0) != 0x3058414E) return 0;
 
                 file.Read(buffer, 0x48);

src/LibHac/IO/AesXtsFile.cs

@@ -1,7 +1,4 @@
 using System;
-using System.IO;
-using System.Security.Cryptography;
-using System.Text;
 
 namespace LibHac.IO
 {
@@ -13,14 +10,10 @@ namespace LibHac.IO
         private byte[] VerificationKey { get; }
         private int BlockSize { get; }
 
-        public byte[] Hmac { get; private set; }
+        private AesXtsFileHeader Header { get; }
-        public byte[][] EncKeys { get; } = Util.CreateJaggedArray<byte[][]>(2, 0x10);
-        public byte[][] Keys { get; } = Util.CreateJaggedArray<byte[][]>(2, 0x10);
-        public byte[] Key { get; } = new byte[0x20];
-        public long Length { get; private set; }
         private IStorage BaseStorage { get; }
 
-        private const int HeaderLength = 0x4000;
+        internal const int HeaderLength = 0x4000;
 
         public AesXtsFile(OpenMode mode, IFile baseFile, string path, ReadOnlySpan<byte> kekSeed, ReadOnlySpan<byte> verificationKey, int blockSize)
         {
@@ -31,60 +24,15 @@ namespace LibHac.IO
             VerificationKey = verificationKey.ToArray();
             BlockSize = blockSize;
 
-            ReadHeader(BaseFile);
+            Header = new AesXtsFileHeader(BaseFile);
 
-            DeriveKeys();
+            if (!Header.TryDecryptHeader(Path, KekSeed, VerificationKey))
-            Storage encStorage = new FileStorage(BaseFile).Slice(HeaderLength, Length);
-            BaseStorage = new CachedStorage(new Aes128XtsStorage(encStorage, Key, BlockSize, true), 4, true);
-        }
-
-        private void ReadHeader(IFile file)
-        {
-            var reader = new BinaryReader(file.AsStream());
-
-            Hmac = reader.ReadBytes(0x20);
-            string magic = reader.ReadAscii(4);
-            reader.BaseStream.Position += 4;
-            if (magic != "NAX0") throw new InvalidDataException("Not an NAX0 file");
-            EncKeys[0] = reader.ReadBytes(0x10);
-            EncKeys[1] = reader.ReadBytes(0x10);
-            Length = reader.ReadInt64();
-        }
-
-        private void DeriveKeys()
-        {
-            var validationHashKey = new byte[0x60];
-            BaseFile.Read(validationHashKey, 0x20);
-
-            var naxSpecificKeys = Util.CreateJaggedArray<byte[][]>(2, 0x10);
-
-            // Use the sd path to generate the kek for this NAX0
-            var hash = new HMACSHA256(KekSeed);
-            byte[] sdPathBytes = Encoding.ASCII.GetBytes(Path);
-            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);
-            Array.Copy(Keys[0], 0, Key, 0, 0x10);
-            Array.Copy(Keys[1], 0, Key, 0x10, 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(VerificationKey);
-
-            if (Util.ArraysEqual(Hmac, validationMac))
             {
-                return;
+                throw new ArgumentException("NAX0 key derivation failed.");
             }
 
-            throw new ArgumentException("NAX0 key derivation failed.");
+            Storage encStorage = new FileStorage(BaseFile).Slice(HeaderLength, Header.Size);
+            BaseStorage = new CachedStorage(new Aes128XtsStorage(encStorage, Header.DecryptedKey1, Header.DecryptedKey2, BlockSize, true), 4, true);
         }
 
         public override int Read(Span<byte> destination, long offset)
@@ -110,7 +58,7 @@ namespace LibHac.IO
 
         public override long GetSize()
         {
-            return Length;
+            return Header.Size;
         }
 
         public override void SetSize(long size)

src/LibHac/IO/AesXtsFileHeader.cs

@@ -0,0 +1,116 @@
+using System;
+using System.IO;
+using System.Runtime.InteropServices;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace LibHac.IO
+{
+    public class AesXtsFileHeader
+    {
+        private const uint AesXtsFileMagic = 0x3058414E;
+        public byte[] Signature { get; set; } = new byte[0x20];
+        public uint Magic { get; }
+        public byte[] EncryptedKey1 { get; } = new byte[0x10];
+        public byte[] EncryptedKey2 { get; } = new byte[0x10];
+        public long Size { get; }
+
+        public byte[] DecryptedKey1 { get; } = new byte[0x10];
+        public byte[] DecryptedKey2 { get; } = new byte[0x10];
+        public byte[] Kek1 { get; } = new byte[0x10];
+        public byte[] Kek2 { get; } = new byte[0x10];
+
+        public AesXtsFileHeader(IFile aesXtsFile)
+        {
+            var reader = new FileReader(aesXtsFile);
+
+            reader.ReadBytes(Signature);
+            Magic = reader.ReadUInt32();
+            reader.Position += 4;
+            reader.ReadBytes(EncryptedKey1);
+            reader.ReadBytes(EncryptedKey2);
+            Size = reader.ReadInt64();
+
+            if (Magic != AesXtsFileMagic)
+            {
+                throw new InvalidDataException("Invalid NAX0 magic value");
+            }
+        }
+
+        public AesXtsFileHeader(byte[] key1, byte[] key2, long fileSize, string path, byte[] kekSeed, byte[] verificationKey)
+        {
+            Array.Copy(key1, DecryptedKey1, 0x10);
+            Array.Copy(key2, DecryptedKey2, 0x10);
+            Magic = AesXtsFileMagic;
+            Size = fileSize;
+
+            EncryptHeader(path, kekSeed, verificationKey);
+        }
+
+        private void EncryptHeader(string path, byte[] kekSeed, byte[] verificationKey)
+        {
+            GenerateKek(kekSeed, path);
+            EncryptKeys();
+            Signature = CalculateHmac(verificationKey);
+        }
+
+        public bool TryDecryptHeader(string path, byte[] kekSeed, byte[] verificationKey)
+        {
+            GenerateKek(kekSeed, path);
+            DecryptKeys();
+
+            byte[] hmac = CalculateHmac(verificationKey);
+            return Util.ArraysEqual(hmac, Signature);
+        }
+
+        private void DecryptKeys()
+        {
+            Crypto.DecryptEcb(Kek1, EncryptedKey1, DecryptedKey1, 0x10);
+            Crypto.DecryptEcb(Kek2, EncryptedKey2, DecryptedKey2, 0x10);
+        }
+
+        private void EncryptKeys()
+        {
+            Crypto.EncryptEcb(Kek1, DecryptedKey1, EncryptedKey1, 0x10);
+            Crypto.EncryptEcb(Kek2, DecryptedKey2, EncryptedKey2, 0x10);
+        }
+
+        private void GenerateKek(byte[] kekSeed, string path)
+        {
+            var hash = new HMACSHA256(kekSeed);
+            byte[] pathBytes = Encoding.ASCII.GetBytes(path);
+
+            byte[] checksum = hash.ComputeHash(pathBytes, 0, pathBytes.Length);
+            Array.Copy(checksum, 0, Kek1, 0, 0x10);
+            Array.Copy(checksum, 0x10, Kek2, 0, 0x10);
+        }
+
+        private byte[] CalculateHmac(byte[] key)
+        {
+            byte[] message = ToBytes(true).AsSpan(0x20).ToArray();
+            var hash = new HMACSHA256(message);
+
+            return hash.ComputeHash(key);
+        }
+
+        public byte[] ToBytes(bool writeDecryptedKey)
+        {
+            uint magic = Magic;
+            long size = Size;
+            byte[] key1 = writeDecryptedKey ? DecryptedKey1 : EncryptedKey1;
+            byte[] key2 = writeDecryptedKey ? DecryptedKey2 : EncryptedKey2;
+
+            var data = new byte[0x80];
+
+            Array.Copy(Signature, data, 0x20);
+            MemoryMarshal.Write(data.AsSpan(0x20), ref magic);
+
+            Array.Copy(key1, 0, data, 0x28, 0x10);
+            Array.Copy(key2, 0, data, 0x38, 0x10);
+
+            MemoryMarshal.Write(data.AsSpan(0x48), ref size);
+
+            return data;
+        }
+    }
+}

src/LibHac/IO/AesXtsFileSystem.cs

@@ -33,7 +33,15 @@ namespace LibHac.IO
 
         public void CreateFile(string path, long size, CreateFileOptions options)
         {
-            throw new NotImplementedException();
+            long containerSize = AesXtsFile.HeaderLength + Util.AlignUp(size, 0x16);
+            BaseFileSystem.CreateFile(path, containerSize, options);
+
+            var header = new AesXtsFileHeader(new byte[0x10], new byte[0x10], size, path, KekSource, ValidationKey);
+
+            using (IFile baseFile = BaseFileSystem.OpenFile(path, OpenMode.Write))
+            {
+                baseFile.Write(header.ToBytes(false), 0);
+            }
         }
 
         public void DeleteDirectory(string path)
@@ -60,8 +68,10 @@ namespace LibHac.IO
         {
             path = PathTools.Normalize(path);
 
-            IFile baseFile = BaseFileSystem.OpenFile(path, mode);
+            IFile baseFile = BaseFileSystem.OpenFile(path, mode | OpenMode.Read);
             var file = new AesXtsFile(mode, baseFile, path, KekSource, ValidationKey, BlockSize);
+
+            file.ToDispose.Add(baseFile);
             return file;
         }
 

src/LibHac/IO/FileBase.cs

@@ -6,7 +6,7 @@ namespace LibHac.IO
     public abstract class FileBase : IFile
     {
         private bool _isDisposed;
-        protected List<IDisposable> ToDispose { get; } = new List<IDisposable>();
+        internal List<IDisposable> ToDispose { get; } = new List<IDisposable>();
 
         public abstract int Read(Span<byte> destination, long offset);
         public abstract void Write(ReadOnlySpan<byte> source, long offset);

src/LibHac/IO/FileReader.cs

@@ -0,0 +1,149 @@
+using System;
+using System.Diagnostics;
+using System.Runtime.InteropServices;
+
+namespace LibHac.IO
+{
+    public class FileReader
+    {
+        private const int BufferSize = 0x10;
+        private IFile _file;
+        private byte[] _buffer;
+        private long _start;
+
+        public long Position { get; set; }
+
+        public FileReader(IFile file)
+        {
+            _file = file;
+            _buffer = new byte[BufferSize];
+        }
+
+        public FileReader(IFile file, long start)
+        {
+            _file = file;
+            _start = start;
+            _buffer = new byte[BufferSize];
+        }
+
+        private void FillBuffer(long offset, int count, bool updatePosition)
+        {
+            Debug.Assert(count <= BufferSize);
+
+            _file.Read(_buffer.AsSpan(0, count), _start + offset);
+            if (updatePosition) Position = offset + count;
+        }
+
+        public byte ReadUInt8(long offset, bool updatePosition)
+        {
+            FillBuffer(offset, sizeof(byte), updatePosition);
+
+            return _buffer[0];
+        }
+
+        public sbyte ReadInt8(long offset, bool updatePosition)
+        {
+            FillBuffer(offset, sizeof(sbyte), updatePosition);
+
+            return (sbyte)_buffer[0];
+        }
+
+        public ushort ReadUInt16(long offset, bool updatePosition)
+        {
+            FillBuffer(offset, sizeof(ushort), updatePosition);
+
+            return MemoryMarshal.Read<ushort>(_buffer);
+        }
+
+        public short ReadInt16(long offset, bool updatePosition)
+        {
+            FillBuffer(offset, sizeof(short), updatePosition);
+
+            return MemoryMarshal.Read<short>(_buffer);
+        }
+
+        public uint ReadUInt32(long offset, bool updatePosition)
+        {
+            FillBuffer(offset, sizeof(uint), updatePosition);
+
+            return MemoryMarshal.Read<uint>(_buffer);
+        }
+
+        public int ReadInt32(long offset, bool updatePosition)
+        {
+            FillBuffer(offset, sizeof(int), updatePosition);
+
+            return MemoryMarshal.Read<int>(_buffer);
+        }
+
+        public ulong ReadUInt64(long offset, bool updatePosition)
+        {
+            FillBuffer(offset, sizeof(ulong), updatePosition);
+
+            return MemoryMarshal.Read<ulong>(_buffer);
+        }
+
+        public long ReadInt64(long offset, bool updatePosition)
+        {
+            FillBuffer(offset, sizeof(long), updatePosition);
+            
+            return MemoryMarshal.Read<long>(_buffer);
+        }
+
+        public float ReadSingle(long offset, bool updatePosition)
+        {
+            FillBuffer(offset, sizeof(float), updatePosition);
+
+            return MemoryMarshal.Read<float>(_buffer);
+        }
+
+        public double ReadDouble(long offset, bool updatePosition)
+        {
+            FillBuffer(offset, sizeof(double), updatePosition);
+
+            return MemoryMarshal.Read<double>(_buffer);
+        }
+
+        public byte[] ReadBytes(long offset, int length, bool updatePosition)
+        {
+            var result = new byte[length];
+            _file.Read(result, offset);
+
+            if (updatePosition) Position = offset + length;
+            return result;
+        }
+
+        public void ReadBytes(Span<byte> destination, long offset, bool updatePosition)
+        {
+            _file.Read(destination, offset);
+
+            if (updatePosition) Position = offset + destination.Length;
+        }
+
+        public byte ReadUInt8(long offset) => ReadUInt8(offset, true);
+        public sbyte ReadInt8(long offset) => ReadInt8(offset, true);
+        public ushort ReadUInt16(long offset) => ReadUInt16(offset, true);
+        public short ReadInt16(long offset) => ReadInt16(offset, true);
+        public uint ReadUInt32(long offset) => ReadUInt32(offset, true);
+        public int ReadInt32(long offset) => ReadInt32(offset, true);
+        public ulong ReadUInt64(long offset) => ReadUInt64(offset, true);
+        public long ReadInt64(long offset) => ReadInt64(offset, true);
+        public float ReadSingle(long offset) => ReadSingle(offset, true);
+        public double ReadDouble(long offset) => ReadDouble(offset, true);
+        public byte[] ReadBytes(long offset, int length) => ReadBytes(offset, length, true);
+        public void ReadBytes(Span<byte> destination, long offset) => ReadBytes(destination, offset, true);
+
+        public byte ReadUInt8() => ReadUInt8(Position, true);
+        public sbyte ReadInt8() => ReadInt8(Position, true);
+        public ushort ReadUInt16() => ReadUInt16(Position, true);
+        public short ReadInt16() => ReadInt16(Position, true);
+        public uint ReadUInt32() => ReadUInt32(Position, true);
+        public int ReadInt32() => ReadInt32(Position, true);
+        public ulong ReadUInt64() => ReadUInt64(Position, true);
+        public long ReadInt64() => ReadInt64(Position, true);
+        public float ReadSingle() => ReadSingle(Position, true);
+        public double ReadDouble() => ReadDouble(Position, true);
+        public byte[] ReadBytes(int length) => ReadBytes(Position, length, true);
+        public void ReadBytes(Span<byte> destination) => ReadBytes(destination, Position, true);
+    }
+}

src/LibHac/IO/HierarchicalRomFileTable.cs

@@ -1,7 +0,0 @@
-namespace LibHac.IO
-{
-    public class HierarchicalRomFileTable
-    {
-
-    }
-}