Exercise $4$:

Suppose that a plaintext message consisting of capital letters is cut into groups of two letters. The last block

may consist of a single letter. Each letter is replaced by a $2-$digit code, as shown in the following table. To get

the integer that encodes two consecutive letters, multiply the code of the first letter by $100,$ and add the code

of the second letter. For example, $"$US$"$ is encoded $3533=35**100+33.$ If the last block just has one letter, it is

encoded by this letter, that is$,$ the final block $"A"$ is encoded as $15.$

Question $4\mathrm{.}1$:

Decrypt the following RSA$-$encoded message. It is made of six blocks. The public key is: $(e=1357,n=7387).$

$967,479,3822,1258,2391,560$

Question $4\mathrm{.}2$:

Decrypt the following RSA$-$encoded message. It is made of three blocks. The public key is: $(e=95,n=8137).$

$2320,5423,6138$