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The secret matrix is <math> \begin{matrix} - \frac{2}{3} & 0 & \frac{2}{3} \\ 0 & 1 & 0 \\ 4 &0 & -1 \end{matrix} </math>.<br> | The secret matrix is <math> \begin{matrix} - \frac{2}{3} & 0 & \frac{2}{3} \\ 0 & 1 & 0 \\ 4 &0 & -1 \end{matrix} </math>.<br> | ||
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So, <math> \begin{matrix} - \frac{2}{3} & 0 & \frac{2}{3} \\ 0 & 1 & 0 \\ 4 &0 & -1 \end{matrix} * \begin{matrix} - x \\ y \\ z \end{matrix} = \begin{matrix} - 2 \\ 23 \\ 2 \end{matrix} | So, <math> \begin{matrix} - \frac{2}{3} & 0 & \frac{2}{3} \\ 0 & 1 & 0 \\ 4 &0 & -1 \end{matrix} * \begin{matrix} - x \\ y \\ z \end{matrix} = \begin{matrix} - 2 \\ 23 \\ 2 \end{matrix} | ||
Revision as of 07:54, 16 September 2008
Question 1
Bod knows the 3 by 3 secret matrix and encrypted message. Then Bob is able to get encrypted message by multiplying inversed matrix by encrypted message.
Question 2
No. Eve has to find inverse of the secret matrix to decrypt the message.
Question 3
The secret matrix is $ \begin{matrix} - \frac{2}{3} & 0 & \frac{2}{3} \\ 0 & 1 & 0 \\ 4 &0 & -1 \end{matrix} $.
So, $ \begin{matrix} - \frac{2}{3} & 0 & \frac{2}{3} \\ 0 & 1 & 0 \\ 4 &0 & -1 \end{matrix} * \begin{matrix} - x \\ y \\ z \end{matrix} = \begin{matrix} - 2 \\ 23 \\ 2 \end{matrix} $
