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Homework Help: I want to prove if the composite are equal to each other

  1. Mar 20, 2013 #1
    Given f:{0,1}n→{0,1}n, define f′:{0,1}2n→{0,1}2n as follows: for x,r∈{0,1}n define f′(x∘r):=f(x)∘r (where ∘ denotes concatenation). Prove that if f(⋅) is one way permutation then so is f′(⋅).

    i don't understand f′(x∘r):=f(x)∘r how to decompose it in order to prove it

    I tried proving it by using a composition of tow bijection, as a permutation is a sect of bijection function.

    I am stuck on the proof, I dont know how to do the proof
  2. jcsd
  3. Mar 20, 2013 #2


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    What is the definition of {0,1}n?
  4. Mar 20, 2013 #3
    Do you mean ##\{0,1\}^n##?

    What is a "one way" permutation?
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