Encode IXLOVEXMATH using the

cryptosystem in Example $7\mathrm{.}1.$

How do i solve problem $1$ based on the example given $?$

Example $7\mathrm{.}1.$ One of the first and most

famous private key cryptosystems was the shift code used by Julius Caesar. We first digitize the alphabet by letting $A=00,B=01,$dots,$Z=25.$ The encoding function will be

$f(p)=p+3$mod$26$;

that is$,A|D,B|E,$dots,$Z|C||.$ The decoding function is then

$f^{-1}(p)=p-3$mod$26=p+23$mod$26.$

Suppose we receive the encoded message DOJHEUD. To decode this message, we first digitize it:

$3,14,9,7,4,20,3$

Next we apply the inverse transformation to get

$0,11,6,4,1,17,0,$

or ALGEBRA. Notice here that there is nothing special about either of the numbers $3$ or $26.$ We could have used a larger alphabet or a different shift.

in$-$context