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https://issues.apache.org/jira/browse/HADOOP-1385?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Owen O'Malley updated HADOOP-1385:
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Attachment: 1385.patch
This patch adds a new function MD5Hash.quarterDigest() that gives the user the
first 4 bytes as a int. It replaces the current function with a call to
quarterDigest. It adds test cases for the old halfDigest, the new
quarterDigest, and a test of the collision.
> MD5Hash has a bad hash function
> -------------------------------
>
> Key: HADOOP-1385
> URL: https://issues.apache.org/jira/browse/HADOOP-1385
> Project: Hadoop
> Issue Type: Bug
> Components: io
> Affects Versions: 0.12.3
> Reporter: Owen O'Malley
> Assigned To: Owen O'Malley
> Fix For: 0.13.0
>
> Attachments: 1385.patch
>
>
> The MD5Hash class has a really bad hash function, that will cause most most
> md5s to hash to 0xFFFFFFxx leaving only the low order byte as meaningful. The
> problem comes from the automatic sign extension when promoting from byte to
> int.
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