[freenet-cvs] r21030 - branches/saltedhashstore/freenet/src/freenet/support

[j16s...@freenetproject.org]

Author: j16sdiz
Date: 2008-07-10 14:24:34 +0000 (Thu, 10 Jul 2008)
New Revision: 21030

Modified:
   branches/saltedhashstore/freenet/src/freenet/support/BloomFilter.java
Log:
squeeze more hashes from SHA-256 for BloomFilter

Modified: branches/saltedhashstore/freenet/src/freenet/support/BloomFilter.java
===================================================================
--- branches/saltedhashstore/freenet/src/freenet/support/BloomFilter.java       
2008-07-10 13:45:09 UTC (rev 21029)
+++ branches/saltedhashstore/freenet/src/freenet/support/BloomFilter.java       
2008-07-10 14:24:34 UTC (rev 21030)
@@ -93,16 +93,16 @@

                MessageDigest md = SHA256.getMessageDigest();
                try {
-                       ByteBuffer bf = null;
+                       byte[] lastDigest = key;
+                       ByteBuffer bf = ByteBuffer.wrap(lastDigest);

                        for (int i = 0; i < k; i++) {
-                               if (bf == null || bf.remaining() < 8) {
-                                       md.update(key);
-                                       md.update((byte) i);
-                                       bf = ByteBuffer.wrap(md.digest());
+                               if (bf.remaining() < 4) {
+                                       lastDigest = md.digest(lastDigest);
+                                       bf = ByteBuffer.wrap(lastDigest);
                                }

-                               hashes[i] = (int) ((bf.getLong() & 
Long.MAX_VALUE) % length);
+                               hashes[i] = (int) ((bf.getInt() & 
Long.MAX_VALUE) % length);
                        }
                } finally {
                        SHA256.returnMessageDigest(md);