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From "Dag H. Wanvik (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-5539) Harden password hashing in the builtin authentication service
Date Tue, 20 Dec 2011 22:31:30 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5539?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13173570#comment-13173570

Dag H. Wanvik commented on DERBY-5539:

Thanks, Knut. I read through the patch, and it looks good to me. +1

Nits: Do you need the upper bound in AuthenticationServiceBase#getIntProperty? 
The Javadoc for Changes10_9#testBuiltinAuthenticationWithConfigurableHash is a little ambiguous
in its use of "only".
Could you test with the salt in the upgrade test by reading the property first?
> Harden password hashing in the builtin authentication service
> -------------------------------------------------------------
>                 Key: DERBY-5539
>                 URL: https://issues.apache.org/jira/browse/DERBY-5539
>             Project: Derby
>          Issue Type: Improvement
>          Components: Services
>    Affects Versions:
>            Reporter: Knut Anders Hatlen
>            Assignee: Knut Anders Hatlen
>         Attachments: d5539-1a.diff
> The Open Web Application Security Project has some suggestions on how to make it harder
for an attacker to crack hashed passwords: https://www.owasp.org/index.php/Hashing_Java
> The builtin authentication service doesn't follow all the suggestions. In particular,
it doesn't add a random salt, and it only performs the hash operation once.
> I propose that we add two new properties that makes it possible to configure builtin
to use a random salt and run multiple iterations of the hash operation:
> - derby.authentication.builtin.saltLength - the length of the random salt to add (in
> - derby.authentication.builtin.iterations - the number of times to perform the hash operation
> I'd also suggest that we set the defaults so that random salt and multiple iterations
are used by default. The OWASP page mentions 64 bits of salt (8 bytes) and a minimum of 1000
iterations. I consulted a security expert who thought that these recommendations sounded OK,
but he believed the recommended salt length was likely to be revised and suggested 16 bytes
instead. The only price we pay by going from 8 to 16 bytes, is that we'll need to store 8
bytes extra per user in the database, so I don't see any reason not to set the default for
derby.authentication.builtin.saltLength as high as 16. Setting the default for derby.authentication.builtin.iterations
to 1000 will make authentication of a user somewhat slower (which is the point, really), but
experiments on my machine suggest that running our default hash function (SHA-256) 1000 times
takes around 1 ms. Since authentication only happens when establishing a new connection to
the database, that would be a negligible cost, I think.
> If saltLength is set to 0 and iterations is set to 1, the hashing will be done in the
exact same way as in previous versions.
> Both of the properties should only be respected when the data dictionary version is 10.9
or higher, so that users in soft-upgraded databases can still log in after a downgrade.

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