diff --git a/core/java/src/net/i2p/client/naming/LookupDest.java b/core/java/src/net/i2p/client/naming/LookupDest.java
index d131efade..e412f20ed 100644
--- a/core/java/src/net/i2p/client/naming/LookupDest.java
+++ b/core/java/src/net/i2p/client/naming/LookupDest.java
@@ -54,7 +54,7 @@ class LookupDest {
 
     /** @param h 32 byte hash */
     static Destination lookupHash(I2PAppContext ctx, byte[] h) {
-        Hash key = new Hash(h);
+        Hash key = Hash.create(h);
         Destination rv = null;
         try {
             I2PClient client = new I2PSimpleClient();
diff --git a/core/java/src/net/i2p/data/Certificate.java b/core/java/src/net/i2p/data/Certificate.java
index d7ceabaeb..522200098 100644
--- a/core/java/src/net/i2p/data/Certificate.java
+++ b/core/java/src/net/i2p/data/Certificate.java
@@ -43,6 +43,24 @@ public class Certificate extends DataStructureImpl {
     /** Contains multiple certs */
     public final static int CERTIFICATE_TYPE_MULTIPLE = 4;
 
+    /**
+     * Pull from cache or return new
+     * @throws AIOOBE if not enough bytes
+     * @since 0.8.3
+     */
+    public static Certificate create(byte[] data, int off) {
+        int type = data[off] & 0xff;
+        int length = (int) DataHelper.fromLong(data, off + 1, 2);
+        if (type == 0 && length == 0)
+            return NULL_CERT;
+        // from here down roughly the same as readBytes() below
+        if (length == 0)
+            return new Certificate(type, null);
+        byte[] payload = new byte[length];
+        System.arraycopy(data, off = 3, payload, 0, length);
+        return new Certificate(type, payload);
+    }
+
     /**
      * If null cert, return immutable static instance, else create new
      * @since 0.8.3
diff --git a/core/java/src/net/i2p/data/Destination.java b/core/java/src/net/i2p/data/Destination.java
index a8c176df6..3c823a52b 100644
--- a/core/java/src/net/i2p/data/Destination.java
+++ b/core/java/src/net/i2p/data/Destination.java
@@ -49,20 +49,14 @@ public class Destination extends KeysAndCert {
             throw new DataFormatException("Not enough data (len=" + source.length + " off=" + offset + ")");
         int cur = offset;
         
-        _publicKey = new PublicKey();
-        byte buf[] = new byte[PublicKey.KEYSIZE_BYTES];
-        System.arraycopy(source, cur, buf, 0, PublicKey.KEYSIZE_BYTES);
-        _publicKey.setData(buf);
+        _publicKey = PublicKey.create(source, cur);
         cur += PublicKey.KEYSIZE_BYTES;
         
-        _signingKey = new SigningPublicKey();
-        buf = new byte[SigningPublicKey.KEYSIZE_BYTES];
-        System.arraycopy(source, cur, buf, 0, SigningPublicKey.KEYSIZE_BYTES);
-        _signingKey.setData(buf);
+        _signingKey = SigningPublicKey.create(source, cur);
         cur += SigningPublicKey.KEYSIZE_BYTES;
         
-        _certificate = new Certificate();
-        cur += _certificate.readBytes(source, cur);
+        _certificate = Certificate.create(source, cur);
+        cur += _certificate.size();
         
         return cur - offset;
     }
diff --git a/core/java/src/net/i2p/data/PublicKey.java b/core/java/src/net/i2p/data/PublicKey.java
index 13b0217f5..a52f6a50b 100644
--- a/core/java/src/net/i2p/data/PublicKey.java
+++ b/core/java/src/net/i2p/data/PublicKey.java
@@ -25,6 +25,15 @@ public class PublicKey extends SimpleDataStructure {
 
     private static final SDSCache<PublicKey> _cache = new SDSCache(PublicKey.class, KEYSIZE_BYTES, CACHE_SIZE);
 
+    /**
+     * Pull from cache or return new
+     * @throws AIOOBE if not enough bytes
+     * @since 0.8.3
+     */
+    public static PublicKey create(byte[] data, int off) {
+        return _cache.get(data, off);
+    }
+
     /**
      * Pull from cache or return new
      * @since 0.8.3
diff --git a/core/java/src/net/i2p/data/SigningPublicKey.java b/core/java/src/net/i2p/data/SigningPublicKey.java
index 8187b1c18..e2e0cf367 100644
--- a/core/java/src/net/i2p/data/SigningPublicKey.java
+++ b/core/java/src/net/i2p/data/SigningPublicKey.java
@@ -26,6 +26,15 @@ public class SigningPublicKey extends SimpleDataStructure {
 
     private static final SDSCache<SigningPublicKey> _cache = new SDSCache(SigningPublicKey.class, KEYSIZE_BYTES, CACHE_SIZE);
 
+    /**
+     * Pull from cache or return new
+     * @throws AIOOBE if not enough bytes
+     * @since 0.8.3
+     */
+    public static SigningPublicKey create(byte[] data, int off) {
+        return _cache.get(data, off);
+    }
+
     /**
      * Pull from cache or return new
      * @since 0.8.3
diff --git a/core/java/src/net/i2p/data/i2cp/DestReplyMessage.java b/core/java/src/net/i2p/data/i2cp/DestReplyMessage.java
index 7aaba9c89..788fb36a0 100644
--- a/core/java/src/net/i2p/data/i2cp/DestReplyMessage.java
+++ b/core/java/src/net/i2p/data/i2cp/DestReplyMessage.java
@@ -60,9 +60,7 @@ public class DestReplyMessage extends I2CPMessageImpl {
         } else {
             try {
                 if (size == Hash.HASH_LENGTH) {
-                    Hash h = new Hash();
-                    h.readBytes(in);
-                    _hash = h;
+                    _hash = Hash.create(in);
                 } else {
                     Destination d = new Destination();
                     d.readBytes(in);
diff --git a/history.txt b/history.txt
index 63449fd25..2796a8d01 100644
--- a/history.txt
+++ b/history.txt
@@ -1,3 +1,17 @@
+2010-12-31 zzz
+    * Console:
+      - Make themes and history.txt return 403 on error,
+        not 500, to avoid the new error page
+      - Add logging, enable with routerconsole.log=filename
+      - Link to full history.txt on help page
+    * Data Structures: Caching cleanups
+    * Datagram Dissector: Fix RuntimeException caused by reuse,
+                          preventing iMule from connecting on UDP
+                          (thanks devzero)
+    * i2psnark:
+      - Send cache directive for in-war icons
+    * OCMOSJ: Refactor cache keys for efficiency
+
 2010-12-30 zzz
     * Data Structures:
       - New SDSCache for SimpleDataStructures
diff --git a/router/java/src/net/i2p/router/Blocklist.java b/router/java/src/net/i2p/router/Blocklist.java
index 0f68355db..d401f1532 100644
--- a/router/java/src/net/i2p/router/Blocklist.java
+++ b/router/java/src/net/i2p/router/Blocklist.java
@@ -305,7 +305,7 @@ public class Blocklist {
         if (end1 - start1 == 44 && buf.substring(start1).indexOf(".") < 0) {
             byte b[] = Base64.decode(buf.substring(start1));
             if (b != null)
-                return new Entry(comment, new Hash(b), null, null);
+                return new Entry(comment, Hash.create(b), null, null);
         }
         index = buf.indexOf("-", start1);
         if (index >= 0) {
diff --git a/router/java/src/net/i2p/router/RouterVersion.java b/router/java/src/net/i2p/router/RouterVersion.java
index 4e28a2c8d..c10128fe6 100644
--- a/router/java/src/net/i2p/router/RouterVersion.java
+++ b/router/java/src/net/i2p/router/RouterVersion.java
@@ -18,7 +18,7 @@ public class RouterVersion {
     /** deprecated */
     public final static String ID = "Monotone";
     public final static String VERSION = CoreVersion.VERSION;
-    public final static long BUILD = 5;
+    public final static long BUILD = 6;
 
     /** for example "-test" */
     public final static String EXTRA = "";
diff --git a/router/java/src/net/i2p/router/networkdb/kademlia/PersistentDataStore.java b/router/java/src/net/i2p/router/networkdb/kademlia/PersistentDataStore.java
index 0172dfcc6..429489cf0 100644
--- a/router/java/src/net/i2p/router/networkdb/kademlia/PersistentDataStore.java
+++ b/router/java/src/net/i2p/router/networkdb/kademlia/PersistentDataStore.java
@@ -18,6 +18,7 @@ import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.concurrent.ConcurrentHashMap;
 
+import net.i2p.data.Base64;
 import net.i2p.data.DataFormatException;
 import net.i2p.data.DataStructure;
 import net.i2p.data.Hash;
@@ -481,8 +482,12 @@ class PersistentDataStore extends TransientDataStore {
         try {
             String key = filename.substring(prefix.length());
             key = key.substring(0, key.length() - suffix.length());
-            Hash h = new Hash();
-            h.fromBase64(key);
+            //Hash h = new Hash();
+            //h.fromBase64(key);
+            byte[] b = Base64.decode(key);
+            if (b == null)
+                return null;
+            Hash h = Hash.create(b);
             return h;
         } catch (Exception e) {
             // static
diff --git a/router/java/src/net/i2p/router/transport/udp/UDPTransport.java b/router/java/src/net/i2p/router/transport/udp/UDPTransport.java
index a43d830ce..b55d845ad 100644
--- a/router/java/src/net/i2p/router/transport/udp/UDPTransport.java
+++ b/router/java/src/net/i2p/router/transport/udp/UDPTransport.java
@@ -937,11 +937,9 @@ public class UDPTransport extends TransportImpl implements TimedWeightedPriority
             RouterAddress addr = _externalAddress;
             UDPAddress ua = new UDPAddress(addr);
             int valid = 0;
-            Hash peerHash = new Hash();
             for (int i = 0; i < ua.getIntroducerCount(); i++) {
                 // warning: this is only valid as long as we use the ident hash as their key.
-                peerHash.setData(ua.getIntroducerKey(i));
-                PeerState peer = getPeerState(peerHash);
+                PeerState peer = getPeerState(Hash.create(ua.getIntroducerKey(i)));
                 if (peer != null)
                     valid++;
             }