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Once again a thread on brute forcing sequences.; Strengths of sequences if numbers are known but order is not.
Topic Started: Jan 20 2014, 02:19 AM (173 Views)
tetragrammaton
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I have been wondering, is a sequence of numbers easily brute forced if the numbers are known but their order is not. For instance- If I have a set of 99 numbers or in this case symbols of ASCII and I am using them as a key in a particular order How difficult would it be to brute force this sequence if I do not know their order? I know that if I know the symbols it requires a factorial of 99! This is a large number. I know that it is much more difficult to brute force a 99 digit pasword in which the symbols are unknown, but what if they are? Is this still computationally difficult?
Edited by tetragrammaton, Jan 20 2014, 02:19 AM.
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mok-kong shen
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If one could "perfectly" scramble a sequence of n symbols, then the chance/probability of bruteforcing would be 2/n!. The problem is how to do a perfect scrambling. Note that one's communication partner must be able to reverse exactly the same (secret) scrambling. (If one had a "truly" random bit sequence (OTP), one could perform perfect scrambling. But one would have then the problem of transport and management of OTP.)
Edited by mok-kong shen, Jan 20 2014, 04:45 AM.
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fiziwig
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Is there a "gradient" that could be used for hill climbing? Or is the correct permutation "all or nothing"?
If there is not gradient then I don't see how it could possibly be fast enough to be practical. 99! is a lot of permutations to try!
(933 262 154 439 441 526 816 992 388 562 667 004 907 159 682 643 816 214 685 929 638 952 175 999 932 299 156 089 414 639 761 565 182 862 536 979 208 272 237 582 511 852 109 168 640 000 000 000 000 000 000 000 to be exact!)
Edited by fiziwig, Jan 20 2014, 03:52 AM.
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tetragrammaton
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The correct permutation is all or nothing. In this particular case I cannot see how one could chance uppon having any number of the characters in the sequence in the correct places for any one try.
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tetragrammaton
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Im just trying to compare the practicality of a brute force attack on a known string of scrambled symbols to the practicality of a brute force attack on an unknown password.
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