On Wed, 28 Jul 1999 adrian@creative.net.au wrote:
> Does anyone have figures for collisions of URL names when md5'ed ?
> I'm curious to know what it is like in the real world ..
I did some experiments in June 1997 using URLs from our SV cache. I
varied the length/size of an MD5 digest (in bytes) and varied the number
of days in the access log.
trace length, number of number of MD5 collisions for
days unique URLs a given URL digest length
4 5 6 16
------------- ----------- ------ --- --- ---
1 375066 13 0 0 0
5 1494774 257 1 0 0
10 2619168 817 2 0 0
Thus, for six byte and longer URL digests, there were no collisions in
the given set. A four byte URL digest gives negligible number of
collisions (817 or 0.04% for a 10 day trace). The standard MD5 digest
length is 16 bytes.
Alex.
Received on Tue Jul 29 2003 - 13:15:59 MDT
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