On Fri, Aug 1, 2008 at 7:08 AM, Matthew Toseland
<toad at amphibian.dyndns.org> wrote:
> On Thursday 10 July 2008 15:24, j16sdiz at freenetproject.org wrote:
>> 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);
>
> Surely & Integer.MAX_VALUE ??
.. & Integer.MAX_VALUE remove the highest bit
this make sure the value is positive.
(btw, this code is removed in the latest version)
>
>> }
>> } finally {
>> SHA256.returnMessageDigest(md);
>>
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>>
>>
>
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