Add NCA2 support

src/LibHac/IO/NcaUtils/Nca.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using LibHac.IO.RomFs;
@@ -7,6 +8,9 @@ namespace LibHac.IO.NcaUtils
 {
     public class Nca : IDisposable
     {
+        private const int HeaderSize = 0xc00;
+        private const int HeaderSectorSize = 0x200;
+        
         public NcaHeader Header { get; }
         public string NcaId { get; set; }
         public string Filename { get; set; }
@@ -334,9 +338,9 @@ namespace LibHac.IO.NcaUtils
             return new NcaHeader(new BinaryReader(OpenHeaderStorage().AsStream()), Keyset);
         }
 
-        private CachedStorage OpenHeaderStorage()
+        public IStorage OpenHeaderStorage()
         {
-            long size = 0xc00;
+            long size = HeaderSize;
 
             // Encrypted portion continues until the first section
             if (Sections.Any(x => x != null))
@@ -344,7 +348,42 @@ namespace LibHac.IO.NcaUtils
                 size = Sections.Where(x => x != null).Min(x => x.Offset);
             }
 
-            return new CachedStorage(new Aes128XtsStorage(BaseStorage.Slice(0, size), Keyset.HeaderKey, 0x200, true), 1, true);
+            IStorage header = new CachedStorage(new Aes128XtsStorage(BaseStorage.Slice(0, size), Keyset.HeaderKey, HeaderSectorSize, true), 1, true);
+            int version = ReadHeaderVersion(header);
+
+            if (version == 2)
+            {
+                header = OpenNca2Header(size);
+            }
+
+            return header;
+        }
+
+        private int ReadHeaderVersion(IStorage header)
+        {
+            if (Header != null)
+            {
+               return Header.Version;
+            }
+            else
+            {
+                Span<byte> buf = stackalloc byte[1];
+                header.Read(buf, 0x203);
+                return buf[0] - '0';
+            }
+        }
+
+        private IStorage OpenNca2Header(long size)
+        {
+            var sources = new List<IStorage>();
+            sources.Add(new CachedStorage(new Aes128XtsStorage(BaseStorage.Slice(0, 0x400), Keyset.HeaderKey, HeaderSectorSize, true), 1, true));
+
+            for (int i = 0x400; i < size; i += HeaderSectorSize)
+            {
+                sources.Add(new CachedStorage(new Aes128XtsStorage(BaseStorage.Slice(i, HeaderSectorSize), Keyset.HeaderKey, HeaderSectorSize, true), 1, true));
+            }
+
+            return new ConcatenationStorage(sources, true);
         }
 
         private void DecryptKeyArea(Keyset keyset)

src/LibHac/IO/NcaUtils/NcaStructs.cs

@@ -1,4 +1,5 @@
-using System.IO;
+using System;
+using System.IO;
 
 namespace LibHac.IO.NcaUtils
 {
@@ -7,6 +8,7 @@ namespace LibHac.IO.NcaUtils
         public byte[] Signature1; // RSA-PSS signature over header with fixed key.
         public byte[] Signature2; // RSA-PSS signature over header with key in NPDM.
         public string Magic;
+        public int Version;
         public DistributionType Distribution; // System vs gamecard.
         public ContentType ContentType;
         public byte CryptoType; // Which keyblob (field 1)
@@ -33,7 +35,12 @@ namespace LibHac.IO.NcaUtils
             Signature1 = reader.ReadBytes(0x100);
             Signature2 = reader.ReadBytes(0x100);
             Magic = reader.ReadAscii(4);
-            if (Magic != "NCA3") throw new InvalidDataException("Not an NCA3 file");
+
+            if (!Magic.StartsWith("NCA") || Magic[3] < '0' || Magic[3] > '9')
+                throw new InvalidDataException("Unable to decrypt NCA header, or the file is not an NCA file.");
+
+            Version = Magic[3] - '0';
+            if (Version != 2 && Version != 3) throw new NotSupportedException($"NCA version {Version} is not supported.");
 
             reader.BaseStream.Position -= 4;
             SignatureData = reader.ReadBytes(0x200);

src/hactoolnet/CliParser.cs

@@ -26,6 +26,7 @@ namespace hactoolnet
             new CliOption("section1dir", 1, (o, a) => o.SectionOutDir[1] = a[0]),
             new CliOption("section2dir", 1, (o, a) => o.SectionOutDir[2] = a[0]),
             new CliOption("section3dir", 1, (o, a) => o.SectionOutDir[3] = a[0]),
+            new CliOption("header", 1, (o, a) => o.HeaderOut = a[0]),
             new CliOption("exefs", 1, (o, a) => o.ExefsOut = a[0]),
             new CliOption("exefsdir", 1, (o, a) => o.ExefsOutDir = a[0]),
             new CliOption("romfs", 1, (o, a) => o.RomfsOut = a[0]),
@@ -169,6 +170,7 @@ namespace hactoolnet
             sb.AppendLine("  --titlekeys <file>   Load title keys from an external file.");
             sb.AppendLine("NCA options:");
             sb.AppendLine("  --plaintext <file>   Specify file path for saving a decrypted copy of the NCA.");
+            sb.AppendLine("  --header <file>      Specify Header file path.");
             sb.AppendLine("  --section0 <file>    Specify Section 0 file path.");
             sb.AppendLine("  --section1 <file>    Specify Section 1 file path.");
             sb.AppendLine("  --section2 <file>    Specify Section 2 file path.");

src/hactoolnet/Options.cs

@@ -17,6 +17,7 @@ namespace hactoolnet
         public string ConsoleKeyFile;
         public string[] SectionOut = new string[4];
         public string[] SectionOutDir = new string[4];
+        public string HeaderOut;
         public string ExefsOut;
         public string ExefsOutDir;
         public string RomfsOut;

src/hactoolnet/ProcessNca.cs

@@ -15,6 +15,15 @@ namespace hactoolnet
             using (IStorage file = new LocalStorage(ctx.Options.InFile, FileAccess.Read))
             {
                 var nca = new Nca(ctx.Keyset, file, false);
+
+                if (ctx.Options.HeaderOut != null)
+                {
+                    using (var outHeader = new FileStream(ctx.Options.HeaderOut, FileMode.Create, FileAccess.ReadWrite))
+                    {
+                        nca.OpenHeaderStorage().Slice(0, 0xc00).CopyToStream(outHeader);
+                    }
+                }
+
                 nca.ValidateMasterHashes();
                 nca.ParseNpdm();