Write a script in octave to decrypt a given word$/$phrase using Affine Cipher $.$ It is an example of a Monoalphabetic substitution cipher. The decryption process is done by using the following formula:

$$ P$=$ a$\_$inv $($C$-$ b$)$ mod $26.$

$$where a$,$b are two integers representing the key $($selected randomly, gcd$($a$,26)$ must be $1.$

$$a$\_$inv $*$ a$$ mod $2611$

$$ C is the ciphertext value, and P is the plaintext value.$$

$$ C and P integers with values between $0$ and $25.$

Use the following variable names:

ciphertext for the ciphered text to be decrypted

a$$ where a and $26$ are coprime

b$$ any number between $1$ to $25$

Your code should display the following:

the plaintext

Requirements:

Max $30$ code statements

Hints & tips:

CodeRunner will test your script using different$$ values of a$,$b$,$ and ciphertext

Your output may include the variable name you have used $($CodeRunner will just ignore it$).$

An example showing the expected output $($CodeRunner formatting$)$ for the values specified is given below.

For example:

TestResult

ciphertext$=$ 'UZIZWUZWSU'; a $=5$; b $=8$ ;

Plaintext: STATISTICS

ciphertext$=$ 'OHNQRYUJOQH JEMFHQPQWC'; a $=9$ ; b $=20$ ;

Plaintext: INFORMATION TECHNOLOGY

ciphertext$=$ 'YEAGELRW'; a $=23$ ; b $=16$ ;

Plaintext: GEOMETRY

ciphertext$=\text{'}$NQVRQSD$\text{'}$; a $=2$ ; b $=16$ ;

No modular inverse $2.$ Decryption not possible.