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== Question 3 == | == Question 3 == | ||
| − | The secret matrix is <math> \begin{matrix} - \frac{2}{3} & 0 & \frac{2}{3} \\ 0 & 1 & 0 \\ 4 &0 & -1 \end{matrix} </math>. | + | The secret matrix is <math> \begin{matrix} - \frac{2}{3} & 0 & \frac{2}{3} \\ 0 & 1 & 0 \\ 4 &0 & -1 \end{matrix} </math>.<br> |
| − | 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} | + | |
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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}</math>.<br> | ||
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| + | Then, <math>\begin{matrix} - x \\ y \\ z \end{matrix} = \begin{matrix} - 2 \\ 23 \\ 5 \end{matrix}</math>.<br> | ||
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| + | As a text, it is BWE. | ||
Latest revision as of 07:56, 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} $.
Then, $ \begin{matrix} - x \\ y \\ z \end{matrix} = \begin{matrix} - 2 \\ 23 \\ 5 \end{matrix} $.
As a text, it is BWE.
