From 97258a1838d3c5761b54e6bb88b0d40748c55682 Mon Sep 17 00:00:00 2001
From: Roman Mandeleil <roman@ethergit.com>
Date: Wed, 25 Feb 2015 19:13:03 +0200
Subject: [PATCH] Tweak sha3 to work on part of the byte array by (start,
 length)

---
 .../java/org/ethereum/crypto/HashUtil.java     | 18 ++++++------------
 .../java/org/ethereum/crypto/SHA3Helper.java   | 15 +++++++++++++++
 2 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/ethereumj-core/src/main/java/org/ethereum/crypto/HashUtil.java b/ethereumj-core/src/main/java/org/ethereum/crypto/HashUtil.java
index 8b5414ed..f587142a 100644
--- a/ethereumj-core/src/main/java/org/ethereum/crypto/HashUtil.java
+++ b/ethereumj-core/src/main/java/org/ethereum/crypto/HashUtil.java
@@ -1,16 +1,12 @@
 package org.ethereum.crypto;
 
-import org.ethereum.db.ByteArrayWrapper;
-import org.ethereum.util.LRUMap;
 import org.ethereum.util.RLP;
 import org.ethereum.util.Utils;
-
 import org.spongycastle.crypto.Digest;
 import org.spongycastle.crypto.digests.RIPEMD160Digest;
 import org.spongycastle.util.encoders.Hex;
 
 import java.math.BigInteger;
-
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 
@@ -20,7 +16,6 @@ import static org.ethereum.util.ByteUtil.EMPTY_BYTE_ARRAY;
 public class HashUtil {
 
     private static final int MAX_ENTRIES = 100; // Should contain most commonly hashed values
-    private static LRUMap<ByteArrayWrapper, byte[]> sha3Cache = new LRUMap<>(0, MAX_ENTRIES);
     public static final byte[] EMPTY_DATA_HASH = sha3(EMPTY_BYTE_ARRAY);
     public static final byte[] EMPTY_LIST_HASH = sha3(RLP.encodeList());
     public static final byte[] EMPTY_TRIE_HASH = sha3(RLP.encodeElement(EMPTY_BYTE_ARRAY));
@@ -40,15 +35,14 @@ public class HashUtil {
     }
 
     public static byte[] sha3(byte[] input) {
-        ByteArrayWrapper inputByteArray = new ByteArrayWrapper(input);
-        byte[] result = sha3Cache.get(inputByteArray);
-        if (result != null)
-            return result;
-        result = SHA3Helper.sha3(input);
-        sha3Cache.put(inputByteArray, result);
-        return result;
+        return SHA3Helper.sha3(input);
     }
 
+    public static byte[] sha3(byte[] input, int start, int length) {
+        return SHA3Helper.sha3(input, start, length);
+    }
+
+
     public static byte[] ripemd160(byte[] message) {
         Digest digest = new RIPEMD160Digest();
         if (message != null) {
diff --git a/ethereumj-core/src/main/java/org/ethereum/crypto/SHA3Helper.java b/ethereumj-core/src/main/java/org/ethereum/crypto/SHA3Helper.java
index 9be34af7..ded97718 100644
--- a/ethereumj-core/src/main/java/org/ethereum/crypto/SHA3Helper.java
+++ b/ethereumj-core/src/main/java/org/ethereum/crypto/SHA3Helper.java
@@ -25,6 +25,10 @@ public class SHA3Helper {
         return sha3(message, new SHA3Digest(DEFAULT_SIZE), true);
     }
 
+    public static byte[] sha3(byte[] message, int start, int length) {
+        return sha3(message, start, length, new SHA3Digest(DEFAULT_SIZE), true);
+    }
+
     protected static String sha3String(String message, Size bitSize) {
         SHA3Digest digest = new SHA3Digest(bitSize.bits);
         return sha3String(message, digest, true);
@@ -66,6 +70,17 @@ public class SHA3Helper {
         return doSha3(message, digest, bouncyencoder);
     }
 
+    private static byte[] sha3(byte[] message, int start, int length, SHA3Digest digest, boolean bouncyencoder) {
+        byte[] hash = new byte[digest.getDigestSize()];
+
+        if (message.length != 0) {
+            digest.update(message, start, length);
+        }
+        digest.doFinal(hash, 0);
+        return hash;
+    }
+
+
     private static byte[] doSha3(byte[] message, SHA3Digest digest, boolean bouncyencoder) {
         byte[] hash = new byte[digest.getDigestSize()];