Make 3DS code more readable

NDecrypt.N3DS/Extensions.cs

@@ -23,6 +23,20 @@ public static bool IsCodeBinary(this ExeFSFileHeader? header)
 
  #region NCCHHeader
 
+ /// <summary>
+ /// Get the initial value for the plain counter
+ /// </summary>
+ public static byte[] PlainIV(this Cart cart, int partitionIndex)
+ {
+ if (cart.Partitions == null)
+ return [];
+ if (partitionIndex < 0 || partitionIndex >= cart.Partitions.Length)
+ return [];
+
+ var header = cart.Partitions[partitionIndex];
+ return PlainIV(header);
+ }
+
  /// <summary>
  /// Get the initial value for the plain counter
  /// </summary>
@@ -38,41 +52,54 @@ public static byte[] PlainIV(this NCCHHeader? header)
  /// <summary>
  /// Get the initial value for the ExeFS counter
  /// </summary>
- public static byte[] ExeFSIV(this NCCHHeader header)
+ public static byte[] ExeFSIV(this Cart cart, int partitionIndex)
  {
- if (header == null)
+ if (cart.Partitions == null)
+ return [];
+ if (partitionIndex < 0 || partitionIndex >= cart.Partitions.Length)
  return [];
 
- byte[] partitionIdBytes = BitConverter.GetBytes(header.PartitionId);
- return [.. partitionIdBytes, .. Constants.ExefsCounter];
+ var header = cart.Partitions[partitionIndex];
+ return ExeFSIV(header);
  }
 
  /// <summary>
- /// Get the initial value for the RomFS counter
+ /// Get the initial value for the ExeFS counter
  /// </summary>
- public static byte[] RomFSIV(this NCCHHeader header)
+ public static byte[] ExeFSIV(this NCCHHeader? header)
  {
  if (header == null)
  return [];
 
  byte[] partitionIdBytes = BitConverter.GetBytes(header.PartitionId);
- return [.. partitionIdBytes, .. Constants.RomfsCounter];
+ return [.. partitionIdBytes, .. Constants.ExefsCounter];
  }
 
  /// <summary>
- /// NCCH boot rom key
+ /// Get the initial value for the RomFS counter
  /// </summary>
- public static BigInteger KeyX2C { get; set; }
+ public static byte[] RomFSIV(this Cart cart, int partitionIndex)
+ {
+ if (cart.Partitions == null)
+ return [];
+ if (partitionIndex < 0 || partitionIndex >= cart.Partitions.Length)
+ return [];
 
- /// <summary>
- /// Normal AES key
- /// </summary>
- public static BigInteger NormalKey { get; set; }
+ var header = cart.Partitions[partitionIndex];
+ return RomFSIV(header);
+ }
 
  /// <summary>
- /// NCCH AES key
+ /// Get the initial value for the RomFS counter
  /// </summary>
- public static BigInteger NormalKey2C { get; set; }
+ public static byte[] RomFSIV(this NCCHHeader? header)
+ {
+ if (header == null)
+ return [];
+
+ byte[] partitionIdBytes = BitConverter.GetBytes(header.PartitionId);
+ return [.. partitionIdBytes, .. Constants.RomfsCounter];
+ }
 
  #endregion
 
@@ -193,6 +220,14 @@ public static MediaTypeIndex MediaTypeIndex(this NCSDHeader? header)
  return (MediaTypeIndex)header.PartitionFlags[(int)NCSDFlags.MediaTypeIndex];
  }
 
+ /// <summary>
+ /// Media Unit Size i.e. u32 MediaUnitSize = 0x200*2^flags[6];
+ /// </summary>
+ public static uint MediaUnitSize(this Cart cart)
+ {
+ return cart.Header.MediaUnitSize();
+ }
+
  /// <summary>
  /// Media Unit Size i.e. u32 MediaUnitSize = 0x200*2^flags[6];
  /// </summary>
@@ -217,22 +252,6 @@ public static MediaCardDeviceType MediaCardDevice2X(this NCSDHeader? header)
 
  #endregion
 
- #region PartitionTableEntry
-
- /// <summary>
- /// Check for a valid partition
- /// </summary>
- /// <returns>True if the offset and length are not 0, false otherwise</returns>
- public static bool IsValid(this PartitionTableEntry? entry)
- {
- if (entry == null)
- return false;
-
- return entry.Offset != 0 && entry.Length != 0;
- }
-
- #endregion
-
  #region Ticket
 
  /// <summary>

NDecrypt.N3DS/Serializer.cs

@@ -49,6 +49,21 @@ internal static class Serializer
  }
  }
 
+ cart.Partitions = new NCCHHeader[8];
+ for (int i = 0; i < 8; i++)
+ {
+ // Check the entry is valid
+ var tableEntry = cart.Header.PartitionsTable![i];
+ if (tableEntry == null || tableEntry.Offset == 0 || tableEntry.Length == 0)
+ continue;
+
+ // Seek to the beginning of the NCCH partition
+ long offset = tableEntry.Offset * cart.Header.ImageSizeInMediaUnits;
+ reader.BaseStream.Seek(offset, SeekOrigin.Begin);
+
+ cart.Partitions[i] = ReadNCCHHeader(reader, readSignature: true);
+ }
+
  return cart;
  }
  catch