Messages in this thread | | | Subject | Re: Algoritmic Complexity Attacks and 2.4.20 the dcache code | From | "David S. Miller" <> | Date | 29 May 2003 20:57:47 -0700 |
| |
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/
| |