From d6e441fe6483d8dc76ffad62a7abec1420f83154 Mon Sep 17 00:00:00 2001
From: morkt <muvluv.ru@gmail.com>
Date: Tue, 15 Aug 2017 16:07:54 +0400
Subject: [PATCH] (KiriKiri): added variation of CX encryption scheme.

---
 ArcFormats/KiriKiri/CryptAlgorithms.cs | 16 +++++++++++++
 ArcFormats/KiriKiri/KiriKiriCx.cs      | 32 +++++++++++++++++++++++---
 2 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/ArcFormats/KiriKiri/CryptAlgorithms.cs b/ArcFormats/KiriKiri/CryptAlgorithms.cs
index b4269cf4..12d8d03d 100644
--- a/ArcFormats/KiriKiri/CryptAlgorithms.cs
+++ b/ArcFormats/KiriKiri/CryptAlgorithms.cs
@@ -967,6 +967,22 @@ namespace GameRes.Formats.KiriKiri
         Dictionary<string, string> KnownNames = null;
     }
 
+    [Serializable]
+    public class NanaCxCrypt : SenrenCxCrypt
+    {
+        uint m_random_seed;
+
+        public NanaCxCrypt (CxScheme scheme, uint seed) : base (scheme)
+        {
+            m_random_seed = seed;
+        }
+
+        internal override CxProgram NewProgram (uint seed)
+        {
+            return new CxProgramNana (seed, m_random_seed, ControlBlock);
+        }
+    }
+
     [Serializable]
     public class KissCrypt : ICrypt
     {
diff --git a/ArcFormats/KiriKiri/KiriKiriCx.cs b/ArcFormats/KiriKiri/KiriKiriCx.cs
index 2d02e899..55bcd9fa 100644
--- a/ArcFormats/KiriKiri/KiriKiriCx.cs
+++ b/ArcFormats/KiriKiri/KiriKiriCx.cs
@@ -217,7 +217,7 @@ namespace GameRes.Formats.KiriKiri
 
         CxProgram GenerateProgram (uint seed)
         {
-            var program = new CxProgram (seed, ControlBlock);
+            var program = NewProgram (seed);
             for (int stage = 5; stage > 0; --stage)
             {
                 if (EmitCode (program, stage))
@@ -228,6 +228,11 @@ namespace GameRes.Formats.KiriKiri
             throw new CxProgramException ("Overly large CxEncryption bytecode");
         }
 
+        internal virtual CxProgram NewProgram (uint seed)
+        {
+            return new CxProgram (seed, ControlBlock);
+        }
+
         bool EmitCode (CxProgram program, int stage)
         {
             return program.EmitNop (5)                      // 0x57 0x56 0x53 0x51 0x52
@@ -437,7 +442,7 @@ namespace GameRes.Formats.KiriKiri
         private List<uint>  m_code = new List<uint> (LengthLimit);
         private uint[]      m_ControlBlock;
         private int         m_length;
-        private uint        m_seed;
+        protected uint      m_seed;
 
         class Context
         {
@@ -562,7 +567,7 @@ namespace GameRes.Formats.KiriKiri
             return EmitUInt32 (GetRandom());
         }
 
-        public uint GetRandom ()
+        public virtual uint GetRandom ()
         {
             uint seed = m_seed;
             m_seed = 1103515245 * seed + 12345;
@@ -570,6 +575,27 @@ namespace GameRes.Formats.KiriKiri
         }
     }
 
+    internal class CxProgramNana : CxProgram
+    {
+        protected uint  m_random_seed;
+
+        public CxProgramNana (uint seed, uint random_seed, uint[] control_block) : base (seed, control_block)
+        {
+            m_random_seed = random_seed;
+        }
+
+        public override uint GetRandom ()
+        {
+            uint s = m_seed ^ (m_seed << 17);
+            s ^= (s << 18) | (s >> 15);
+            m_seed = ~s;
+            uint r = m_random_seed ^ (m_random_seed << 13);
+            r ^= r >> 17;
+            m_random_seed = r ^ (r << 5);
+            return m_seed ^ m_random_seed;
+        }
+    }
+
     /* CxEncryption base branch order
     OddBranchOrder
     {