From fc3a604cd4c3711bb8e0e78fa1da21723f0d5ed4 Mon Sep 17 00:00:00 2001
From: Maschell <Maschell@gmx.de>
Date: Tue, 30 Apr 2019 14:25:29 +0200
Subject: [PATCH] Optimize the random access of the non hashed files

---
 .../implementations/FSTDataProviderNUSTitle.java | 13 ++++---------
 .../jnus/utils/cryptography/NUSDecryption.java   | 16 +---------------
 2 files changed, 5 insertions(+), 24 deletions(-)

diff --git a/src/de/mas/wiiu/jnus/implementations/FSTDataProviderNUSTitle.java b/src/de/mas/wiiu/jnus/implementations/FSTDataProviderNUSTitle.java
index 2be617b..d434e23 100644
--- a/src/de/mas/wiiu/jnus/implementations/FSTDataProviderNUSTitle.java
+++ b/src/de/mas/wiiu/jnus/implementations/FSTDataProviderNUSTitle.java
@@ -91,7 +91,7 @@ public class FSTDataProviderNUSTitle implements FSTDataProvider, HasNUSTitle {
 
         long streamOffset = payloadOffset;
 
-        long streamFilesize = size;
+        long streamFilesize = c.getEncryptedFileSize();
         if (c.isHashed()) {
             streamOffset = (payloadOffset / 0xFC00) * 0x10000;
             long offsetInBlock = payloadOffset - ((streamOffset / 0x10000) * 0xFC00);
@@ -110,16 +110,11 @@ public class FSTDataProviderNUSTitle implements FSTDataProvider, HasNUSTitle {
                 streamFilesize = curVal;
             }
         } else {
-            if (size != entry.getFileSize()) {
-                streamOffset = (payloadOffset / 0x8000) * 0x8000;
-                
-                // We need the missing bytes of the previous blocks + the size we want to read.
-                streamFilesize = size;                
-                long offsetInBlock = offset - streamOffset;
-                streamFilesize += offsetInBlock;
+            if (size != entry.getFileSize()) {             
+                streamFilesize = size;
                 
                 // We need the previous IV if we don't start at the first block.
-                if (payloadOffset >= 0x8000 && payloadOffset % 0x8000 == 0) {
+                if (payloadOffset >= 16) {
                     streamOffset -= 16;
                     streamFilesize += 16;
                 }
diff --git a/src/de/mas/wiiu/jnus/utils/cryptography/NUSDecryption.java b/src/de/mas/wiiu/jnus/utils/cryptography/NUSDecryption.java
index 00ad9b0..722c2b8 100644
--- a/src/de/mas/wiiu/jnus/utils/cryptography/NUSDecryption.java
+++ b/src/de/mas/wiiu/jnus/utils/cryptography/NUSDecryption.java
@@ -91,13 +91,8 @@ public class NUSDecryption extends AESDecryption {
         int skipoffset = (int) (fileOffset % 0x8000);
 
         try {
-
-            // If we are at the beginning of a block, but it's not the first one,
-            // we need to get the IV from the last 16 bytes of the previous block.
-            // while beeing paranoid to exactly read 16 bytes but not more. Reading more
-            // would destroy our input stream.
             // The input stream has been prepared to start 16 bytes earlier on this case.
-            if (fileOffset >= 0x8000 && fileOffset % 0x8000 == 0) {
+            if (fileOffset >= 16) {
                 int toRead = 16;
                 byte[] data = new byte[toRead];
                 int readTotal = 0;
@@ -119,15 +114,6 @@ public class NUSDecryption extends AESDecryption {
             long toRead = Utils.align(filesize + 15, 16);
 
             do {
-                // In case we start on the middle of a block we need to consume the "garbage" and save the
-                // current IV.
-                if (skipoffset > 0) {
-                    int skippedBytes = StreamUtils.getChunkFromStream(inputStream, blockBuffer, overflow, skipoffset);
-                    if (skippedBytes >= 16) {
-                        IV = Arrays.copyOfRange(blockBuffer, skippedBytes - 16, skippedBytes);
-                    }
-                    skipoffset = 0;
-                }
 
                 int curReadSize = BLOCKSIZE;
                 if (toRead < BLOCKSIZE) {