handouts/ho06.tex
changeset 435 4603e6bb80c8
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   559 \noindent for $z$. Again that is easy, but it does not allow 
   559 \noindent for $z$. Again that is easy, but it does not allow 
   560 us to know $r_i$, because then we would again need to solve
   560 us to know $r_i$, because then we would again need to solve
   561 a modular logarithm problem. Let us call an $h_i$ which was 
   561 a modular logarithm problem. Let us call an $h_i$ which was 
   562 solved the easy way as \emph{bogus}. Alice has to produce
   562 solved the easy way as \emph{bogus}. Alice has to produce
   563 bogus $h_i$ for all bits that are going to be $1$ in advance!
   563 bogus $h_i$ for all bits that are going to be $1$ in advance!
   564 This means she has to guess all the bits correctly. (Yes?)
   564 This means she has to guess all the bits correctly. (Yes? 
       
   565 I let you think about this.)
   565 
   566 
   566 Let us see what happens if she guesses wrongly: Suppose the
   567 Let us see what happens if she guesses wrongly: Suppose the
   567 bit $b_i = 1$ where she thought she will get a 0. Then she has
   568 bit $b_i = 1$ where she thought she will get a 0. Then she has
   568 already sent an $h_i$ and $h_j$ and now must find an $s_i$
   569 already sent an $h_i$ and $h_j$ and now must find an $s_i$
   569 such that 
   570 such that