lkml.org 
[lkml]   [2003]   [May]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: Algoritmic Complexity Attacks and 2.4.20 the dcache code
    From
    Date
    On Thu, 2003-05-29 at 13:42, Scott A Crosby wrote:
    > I highly advise using a universal hashing library, either our own or
    > someone elses. As is historically seen, it is very easy to make silly
    > mistakes when attempting to implement your own 'secure' algorithm.

    Why are you recommending this when after 2 days of going back
    and forth in emails with me you came to the conclusion that for
    performance critical paths such as the hashes in the kernel the Jenkins
    hash was an acceptable choice?

    It is unacceptably costly to use a universal hash, it makes a multiply
    operation for every byte of key input plus a modulo operation at the
    end of the hash computation. All of which can be extremely expensive
    on some architectures.

    I showed and backed this up for you with benchmarks comparing your
    universal hashing code and Jenkins.

    Some embedded folks will have your head on a platter if we end up using
    a universal hash function for the DCACHE solely based upon your advice.
    :-)

    --
    David S. Miller <davem@redhat.com>
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 13:35    [W:2.849 / U:0.320 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site