On 07/20/2010 11:21 AM, Paul Eggert wrote: > While looking at the random-number stuff I found a theoretical > randomness bug in mktemp. The mktemp command currently uses 8 bytes > of randomness to generate a file name, so with an invocation like > this: > > $ mktemp foo.XXXXXXXXXXX > > the file name is not sufficiently random. There are 62 possibilities > for each X, so one needs log2(62**11) random bits to generate a random > 11-character value for the Xs, which is about 65.5 bits, but we are > generating only 64 bits. The more Xs, the more randomness is needed, > so the bug gets more "serious" as the number of Xs grows.
Meanwhile, glibc's mkstemp() only replaces the last 6 X, regardless of how many additional X are present in the template. Do we even need the extra randomness if the template contains more X? -- Eric Blake [email protected] +1-801-349-2682 Libvirt virtualization library http://libvirt.org
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