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Bitwise XOR problem
Topic Started: Aug 3 2008, 03:16 AM (144 Views)
jdege Aug 3 2008, 03:16 AM Post #1
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 In another forum, someone was asking for help with his homework.

Quote:
 
There is a binary sequence a1,a2,...,aN with the properties:
a1a2a3...aN = b1b2...bn...b1b2..bn XOR c1c2c3...cN,
- b1,b2,...,bn is a periodical binary sequence with the period n<<N,
- c1,c2,c3,...,cN is a binary sequence, where the total number of the bigrams 00, 11 is twice large than the total number of bigrams 01, 10.

I must to find a method to compute the period of the binary sequence b1,b2,...,bn and this sequence itself.


First, I wish my classes had had homework problems like this.

Second, I think I see an approach that should work, if n<<N.

Anyone else have any ideas?
When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.
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