Improve AES-CTR performance

hactoolnet/Program.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using libhac;
@@ -35,12 +36,17 @@ namespace hactoolnet
             var title = sdfs.Titles[0x0100E95004038000];
             var nca = title.ProgramNca;
             var romfsStream = nca.OpenSection(1, false);
-            var romfs = new Romfs(romfsStream);
-            var file = romfs.OpenFile("/stream/voice/us/127/127390101.nop");
 
-            using (var output = new FileStream("127390101.nop", FileMode.Create))
+            var romfs = new Romfs(romfsStream);
+            var file = romfs.OpenFile("/bf2.ard");
+
+            using (var progress = new ProgressBar())
+            using (var output = new FileStream("bf2.ard", FileMode.Create))
             {
-                file.CopyTo(output);
+                var watch = Stopwatch.StartNew();
+                file.CopyStream(output, file.Length / 100, progress);
+                watch.Stop();
+                progress.LogMessage(watch.Elapsed.TotalSeconds.ToString());
             }
         }
 
@@ -53,11 +59,15 @@ namespace hactoolnet
                 var romfsStream = nca.OpenSection(1, false);
 
                 var romfs = new Romfs(romfsStream);
-                var bfstm = romfs.OpenFile("/Sound/Resource/Stream/BGM_Castle.bfstm");
+                var bfstm = romfs.OpenFile("/Sound/Resource/Stream/Demo149_1_SoundTrack.bfstm");
 
-                using (var output = new FileStream("BGM_Castle.bfstm", FileMode.Create))
+                using (var progress = new ProgressBar())
+                using (var output = new FileStream("Demo149_1_SoundTrack.bfstm", FileMode.Create))
                 {
-                    bfstm.CopyTo(output);
+                    var watch = Stopwatch.StartNew();
+                    bfstm.CopyStream(output, bfstm.Length, progress);
+                    watch.Stop();
+                    progress.LogMessage(watch.Elapsed.TotalSeconds.ToString());
                 }
             }
         }

libhac/Aes128CounterMode.cs

@@ -21,87 +21,39 @@
 // THE SOFTWARE.
 
 using System;
-using System.Collections.Generic;
 using System.Security.Cryptography;
 
 namespace libhac
 {
-    public class Aes128CounterMode : SymmetricAlgorithm
+    public class CounterModeCryptoTransform
-    {
-        private readonly byte[] _counter = new byte[0x10];
-        private readonly AesManaged _aes;
-
-        public Aes128CounterMode()
-        {
-            _aes = new AesManaged
-            {
-                Mode = CipherMode.ECB,
-                Padding = PaddingMode.None
-            };
-        }
-
-        public override ICryptoTransform CreateEncryptor(byte[] rgbKey, byte[] ignoredParameter)
-        {
-            return new CounterModeCryptoTransform(_aes, rgbKey, _counter);
-        }
-
-        public override ICryptoTransform CreateDecryptor(byte[] rgbKey, byte[] ignoredParameter)
-        {
-            return new CounterModeCryptoTransform(_aes, rgbKey, _counter);
-        }
-
-        public override void GenerateKey()
-        {
-            _aes.GenerateKey();
-        }
-
-        public override void GenerateIV()
-        {
-            // IV not needed in Counter Mode
-        }
-    }
-
-    public class CounterModeCryptoTransform : ICryptoTransform
     {
+        private const int BlockSize = 128;
+        private const int BlockSizeBytes = BlockSize / 8;
         private readonly byte[] _counter;
+        private readonly byte[] _counterEnc = new byte[0x10];
         private readonly ICryptoTransform _counterEncryptor;
-        private readonly Queue<byte> _xorMask = new Queue<byte>();
-        private readonly SymmetricAlgorithm _symmetricAlgorithm;
 
         public CounterModeCryptoTransform(SymmetricAlgorithm symmetricAlgorithm, byte[] key, byte[] counter)
         {
-            if (symmetricAlgorithm == null) throw new ArgumentNullException(nameof(symmetricAlgorithm));
             if (key == null) throw new ArgumentNullException(nameof(key));
             if (counter == null) throw new ArgumentNullException(nameof(counter));
-            if (counter.Length != symmetricAlgorithm.BlockSize / 8)
+            if (counter.Length != BlockSizeBytes)
                 throw new ArgumentException(String.Format("Counter size must be same as block size (actual: {0}, expected: {1})",
-                    counter.Length, symmetricAlgorithm.BlockSize / 8));
+                    counter.Length, BlockSizeBytes));
 
-            _symmetricAlgorithm = symmetricAlgorithm;
             _counter = counter;
-
+            _counterEncryptor = symmetricAlgorithm.CreateEncryptor(key, new byte[BlockSize / 8]);
-            var zeroIv = new byte[_symmetricAlgorithm.BlockSize / 8];
-            _counterEncryptor = symmetricAlgorithm.CreateEncryptor(key, zeroIv);
         }
 
-        public byte[] TransformFinalBlock(byte[] inputBuffer, int inputOffset, int inputCount)
+        public int TransformBlock(byte[] inputBuffer, int inputOffset, byte[] outputBuffer, int outputOffset)
         {
-            var output = new byte[inputCount];
+            EncryptCounterThenIncrement();
-            TransformBlock(inputBuffer, inputOffset, inputCount, output, 0);
+            for (int i = 0; i < 16; i++)
-            return output;
+            {
+                outputBuffer[outputOffset + i] = (byte)(inputBuffer[inputOffset + i] ^ _counterEnc[i]);
             }
 
-        public int TransformBlock(byte[] inputBuffer, int inputOffset, int inputCount, byte[] outputBuffer, int outputOffset)
+            return 16;
-        {
-            for (var i = 0; i < inputCount; i++)
-            {
-                if (NeedMoreXorMaskBytes()) EncryptCounterThenIncrement();
-
-                var mask = _xorMask.Dequeue();
-                outputBuffer[outputOffset + i] = (byte)(inputBuffer[inputOffset + i] ^ mask);
-            }
-
-            return inputCount;
         }
 
         public void UpdateCounter(long offset)
@@ -114,22 +66,10 @@ namespace libhac
             }
         }
 
-        private bool NeedMoreXorMaskBytes()
-        {
-            return _xorMask.Count == 0;
-        }
-
         private void EncryptCounterThenIncrement()
         {
-            var counterModeBlock = new byte[_symmetricAlgorithm.BlockSize / 8];
+            _counterEncryptor.TransformBlock(_counter, 0, _counter.Length, _counterEnc, 0);
-
-            _counterEncryptor.TransformBlock(_counter, 0, _counter.Length, counterModeBlock, 0);
             IncrementCounter();
-
-            foreach (var b in counterModeBlock)
-            {
-                _xorMask.Enqueue(b);
-            }
         }
 
         private void IncrementCounter()
@@ -141,11 +81,6 @@ namespace libhac
             }
         }
 
-        public int InputBlockSize => _symmetricAlgorithm.BlockSize / 8;
-        public int OutputBlockSize => _symmetricAlgorithm.BlockSize / 8;
-        public bool CanTransformMultipleBlocks => true;
-        public bool CanReuseTransform => false;
-
         public void Dispose()
         {
         }

libhac/AesCtrStream.cs

@@ -166,7 +166,7 @@ namespace libhac
                 _decryptor = CreateDecryptor();
 
             //decrypt the sector
-            var retV = _decryptor.TransformBlock(_tempBuffer, 0, ret, buffer, offset);
+            var retV = _decryptor.TransformBlock(_tempBuffer, 0, buffer, offset);
 
             //Console.WriteLine("Decrypting sector {0} == {1} bytes", currentSector, retV);