Date: Sun, 25 May 2008 22:30:52 +0200 From: "Martin Tournoij" <carpetsmoker@rwxrwxrwx.net> To: freebsd-chat@freebsd.org Cc: aryeh.friedman@gmail.com Subject: Re: [OT] looking for a algorithm Message-ID: <20080525203052.GA6996@rwxrwxrwx.net> In-Reply-To: <4839C799.6020104@gmail.com> References: <4839C799.6020104@gmail.com>
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On Sun, May 25, 2008 at 04:10:01PM -0400, Aryeh M. Friedman wrote: > Lets say I have a string of n bits that needs to be filled by repeatedly > applying some function on k strings of m bits where |m|<|n|. Assuming > that m(i) is a random string and n needs to also be random what is the best > way to do this. Note it is possible that k*|m|>|n|. What I have been > thinking so far is: > > ~ Let m' be the average length of m // this is pre-computable > ~ Let n be all 0's > > ~ for i=0 --> k > ~ pos=m'*i > > ~ xor string k[i] onto n starting at pos // wrap around if needed > > ~ While this is simple I wonder if it can be attacked (determine what > k[i]) if k*|m|>|n| (it is trivial to attack if k*|m|<=|n|). Also is there > some way to make attacking hard if k*|m|<=|n|? > > ~ Ideas? So you want us to do your homework...? -- Martin Tournoij carpetsmoker@rwxrwxrwx.net http://www.daemonforums.org Information is the inverse of entropy.
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