From 2779f5ef728866697ea8a9a446e4a2a1e324ffd0 Mon Sep 17 00:00:00 2001
From: Matt Nadareski <mnadareski@outlook.com>
Date: Mon, 27 Sep 2021 10:42:54 -0700
Subject: [PATCH] Better certificate chain reading

---
 NDecrypt/N3DS/Headers/CIAHeader.cs     |  7 +++----
 NDecrypt/N3DS/Headers/Ticket.cs        | 27 ++++++++++++++++++++++++--
 NDecrypt/N3DS/Headers/TitleMetadata.cs | 15 ++++++++++++++
 3 files changed, 43 insertions(+), 6 deletions(-)

diff --git a/NDecrypt/N3DS/Headers/CIAHeader.cs b/NDecrypt/N3DS/Headers/CIAHeader.cs
index 3a304c4..ab1351d 100644
--- a/NDecrypt/N3DS/Headers/CIAHeader.cs
+++ b/NDecrypt/N3DS/Headers/CIAHeader.cs
@@ -101,10 +101,9 @@ namespace NDecrypt.N3DS.Headers
                 header.ContentSize = reader.ReadInt64();
 
                 header.CertificateChain = new Certificate[3];
-                for (int i = 0; i < 3; i++)
-                {
-                    header.CertificateChain[i] = Certificate.Read(reader);
-                }
+                header.CertificateChain[0] = Certificate.Read(reader); // CA
+                header.CertificateChain[1] = Certificate.Read(reader); // Ticket
+                header.CertificateChain[2] = Certificate.Read(reader); // TMD
 
                 header.Ticket = Ticket.Read(reader, header.TicketSize);
                 header.TMDFileData = TitleMetadata.Read(reader, header.TMDFileSize);
diff --git a/NDecrypt/N3DS/Headers/Ticket.cs b/NDecrypt/N3DS/Headers/Ticket.cs
index f9d9bd1..fd7c5b4 100644
--- a/NDecrypt/N3DS/Headers/Ticket.cs
+++ b/NDecrypt/N3DS/Headers/Ticket.cs
@@ -149,6 +149,13 @@ namespace NDecrypt.N3DS.Headers
         /// </remarks>
         public byte[] Limits { get; private set; }
 
+        /// <summary>
+        /// The Content Index of a ticket has its own size defined within itself,
+        /// with seemingly a minimal of 20 bytes, the second u32 in big endian defines
+        /// the full value of X.
+        /// </summary>
+        public int ContentIndexSize { get; private set; }
+
         /// <summary>
         /// Content Index
         /// </summary>
@@ -159,6 +166,14 @@ namespace NDecrypt.N3DS.Headers
         /// </remarks>
         public byte[] ContentIndex { get; private set; }
 
+        /// <summary>
+        /// Certificate chain
+        /// </summary>
+        /// <remarks>
+        /// https://www.3dbrew.org/wiki/Ticket#Certificate_Chain
+        /// </remarks>
+        public Certificate[] CertificateChain { get; set; }
+
         /// <summary>
         /// Read from a stream and get ticket, if possible
         /// </summary>
@@ -214,9 +229,17 @@ namespace NDecrypt.N3DS.Headers
                 tk.Audit = reader.ReadByte();
                 tk.Reserved6 = reader.ReadBytes(0x42);
                 tk.Limits = reader.ReadBytes(0x40);
+                reader.ReadBytes(4);
+                tk.ContentIndexSize = reader.ReadInt32();
+                reader.BaseStream.Seek(-8, SeekOrigin.Current);
+                tk.ContentIndex = reader.ReadBytes(tk.ContentIndexSize);
 
-                if (ticketSize - 0x164 > 0)
-                    tk.ContentIndex = reader.ReadBytes(ticketSize - 0x164);
+                if (ticketSize - (0x164 + tk.ContentIndexSize) > 0)
+                {
+                    tk.CertificateChain = new Certificate[2];
+                    tk.CertificateChain[0] = Certificate.Read(reader); // Ticket
+                    tk.CertificateChain[1] = Certificate.Read(reader); // CA
+                }
 
                 return tk;
             }
diff --git a/NDecrypt/N3DS/Headers/TitleMetadata.cs b/NDecrypt/N3DS/Headers/TitleMetadata.cs
index 5162b01..f52983b 100644
--- a/NDecrypt/N3DS/Headers/TitleMetadata.cs
+++ b/NDecrypt/N3DS/Headers/TitleMetadata.cs
@@ -136,6 +136,14 @@ namespace NDecrypt.N3DS.Headers
         /// </summary>
         public ContentChunkRecord[] ContentChunkRecords { get; private set; }
 
+        /// <summary>
+        /// Certificate chain
+        /// </summary>
+        /// <remarks>
+        /// https://www.3dbrew.org/wiki/Title_metadata#Certificate_Chain
+        /// </remarks>
+        public Certificate[] CertificateChain { get; set; }
+
         /// <summary>
         /// Read from a stream and get ticket metadata, if possible
         /// </summary>
@@ -203,6 +211,13 @@ namespace NDecrypt.N3DS.Headers
                     tm.ContentChunkRecords[i] = ContentChunkRecord.Read(reader);
                 }
 
+                if (metadataSize - (0xC4 + (64 * 0x24) + (tm.ContentCount * 0x30)) > 0)
+                {
+                    tm.CertificateChain = new Certificate[2];
+                    tm.CertificateChain[0] = Certificate.Read(reader); // TMD
+                    tm.CertificateChain[1] = Certificate.Read(reader); // CA
+                }
+
                 return tm;
             }
             catch