From 53df67d4908152b6edaa7a1643d7f24598360e78 Mon Sep 17 00:00:00 2001
From: Michael Schierl <schierlm@gmx.de>
Date: Thu, 7 Sep 2017 22:01:31 +0200
Subject: [PATCH] More arraycopy improvements

In fact, most arraycopy and copyOfRange calls in the class are unneeded,
since Kerl can also directly operate on array slices. Care has been
taken not to introduce new side effects, therefore one copyOfRange call
in `digests` needs to stay. Existing side effects are kept, although
probably undesirable (`signatureFragment` clobbers the `keyFragment`
input parameter).
---
 src/main/java/jota/utils/Signing.java | 26 ++++++--------------------
 1 file changed, 6 insertions(+), 20 deletions(-)

diff --git a/src/main/java/jota/utils/Signing.java b/src/main/java/jota/utils/Signing.java
index 9119f3f..e03543c 100644
--- a/src/main/java/jota/utils/Signing.java
+++ b/src/main/java/jota/utils/Signing.java
@@ -81,19 +81,12 @@ public class Signing {
 
     public int[] signatureFragment(int[] normalizedBundleFragment, int[] keyFragment) {
 
-        int[] hash;
-
         for (int i = 0; i < 27; i++) {
-
-            hash = Arrays.copyOfRange(keyFragment, i * 243, (i + 1) * 243);
-
             for (int j = 0; j < 13 - normalizedBundleFragment[i]; j++) {
                 curl.reset()
-                        .absorb(hash, 0, hash.length)
-                        .squeeze(hash, 0, hash.length);
+                        .absorb(keyFragment, i * 243, 243)
+                        .squeeze(keyFragment, i * 243, 243);
             }
-
-            System.arraycopy(hash, 0, keyFragment, i * 243, 243);
         }
 
         return keyFragment;
@@ -110,41 +103,34 @@ public class Signing {
     public int[] digests(int[] key) {
 
         int[] digests = new int[(int) Math.floor(key.length / 6561) * 243];
-        int[] buffer = new int[243];
 
         for (int i = 0; i < Math.floor(key.length / 6561); i++) {
             int[] keyFragment = Arrays.copyOfRange(key, i * 6561, (i + 1) * 6561);
 
             for (int j = 0; j < 27; j++) {
-
-                buffer = Arrays.copyOfRange(keyFragment, j * 243, (j + 1) * 243);
                 for (int k = 0; k < 26; k++) {
                     curl.reset()
-                            .absorb(buffer)
-                            .squeeze(buffer);
+                            .absorb(keyFragment, j * 243, 243)
+                            .squeeze(keyFragment, j * 243, 243);
                 }
-                System.arraycopy(buffer, 0, keyFragment, j * 243, 243);
             }
 
             curl.reset();
             curl.absorb(keyFragment, 0, keyFragment.length);
-            curl.squeeze(buffer, 0, buffer.length);
-
-            System.arraycopy(buffer, 0, digests, i * 243, 243);
+            curl.squeeze(digests, i * 243, 243);
         }
         return digests;
     }
 
     public int[] digest(int[] normalizedBundleFragment, int[] signatureFragment) {
         curl.reset();
+        ICurl jCurl = SpongeFactory.create(SpongeFactory.Mode.KERL);
         int[] buffer = new int[243];
 
         for (int i = 0; i < 27; i++) {
             buffer = Arrays.copyOfRange(signatureFragment, i * 243, (i + 1) * 243);
 
             for (int j = normalizedBundleFragment[i] + 13; j-- > 0; ) {
-
-                ICurl jCurl = SpongeFactory.create(SpongeFactory.Mode.KERL);
                 jCurl.reset();
                 jCurl.absorb(buffer);
                 jCurl.squeeze(buffer);