slides/slides06.tex
changeset 422 abe178b3197e
parent 419 667a39dda86e
child 423 11b46fa92a85
equal deleted inserted replaced
421:38ddbc59325a 422:abe178b3197e
   425 \begin{enumerate}
   425 \begin{enumerate}
   426 \item For each \bl{$b_i$} Bob checks whether \bl{$s_i$} conforms to the protocol
   426 \item For each \bl{$b_i$} Bob checks whether \bl{$s_i$} conforms to the protocol
   427 
   427 
   428 \begin{center}
   428 \begin{center}
   429 \begin{tabular}{ll}
   429 \begin{tabular}{ll}
   430 \bl{$b_i = 0$}: & \bl{$A^{s_i} \equiv B\;mod\;p$}\\
   430 \bl{$b_i = 0$}: & \bl{$A^{s_i} \equiv h_i\;mod\;p$}\\
   431 \bl{$b_i = 1$}: & \bl{$A^{s_i}  \equiv h_i * h_j^{-1}  \;mod\; p$}\\
   431 \bl{$b_i = 1$}: & \bl{$A^{s_i}  \equiv h_i * h_j^{-1}  \;mod\; p$}\\
   432 \end{tabular}
   432 \end{tabular}
   433 \end{center}\bigskip
   433 \end{center}\bigskip
   434 
   434 
   435 Bob was sent
   435 Bob was sent
   436 
   436 
   437 \begin{center}
   437 \begin{center}
   438 \bl{$r_j - r _j$},  \bl{$r_m - r _j$}, \ldots, \bl{$r_p - r _j$ \;mod \;p} 
   438 \bl{$r_j - r_j$},  \bl{$r_m - r_j$}, \ldots, \bl{$r_p - r_j \;mod \;p - 1$} 
   439 \end{center}
   439 \end{center}
   440 
   440 
   441 where the corresponding bits were 
   441 where the corresponding bits were 
   442 \bl{$1$}; Bob does not know \bl{$r_j$}, he does not know any \bl{$r_i$} where the bit was \bl{$1$}
   442 \bl{$1$}; Bob does not know \bl{$r_j$}, he does not know any \bl{$r_i$} where the bit was \bl{$1$}
   443 \end{enumerate}
   443 \end{enumerate}
   463 \bl{$A^{s_{z+1}} \equiv B * h_j^{-1} \;mod \; p$}
   463 \bl{$A^{s_{z+1}} \equiv B * h_j^{-1} \;mod \; p$}
   464 \end{center}
   464 \end{center}
   465 \end{enumerate}\bigskip\pause
   465 \end{enumerate}\bigskip\pause
   466 
   466 
   467 In order to cheat, Alice has to guess all bits in advance. She
   467 In order to cheat, Alice has to guess all bits in advance. She
   468 has only \bl{$\frac{1}{2}^z$} chance.\bigskip\\
   468 has only \bl{$\frac{1}{2}^z$} chance of doing so.\bigskip\\
   469 
   469 
   470 \small\hspace{7mm}
   470 \small\hspace{7mm}
   471 \textcolor{gray}{(explanation $\rightarrow$ \url{http://goo.gl/irL9GK})}
   471 \textcolor{gray}{(explanation $\rightarrow$ \url{http://goo.gl/irL9GK})}
   472 
   472 
   473 \end{frame}
   473 \end{frame}