CS,Cryptography, GCD, Exponentiation, Primality

I don’t understand this Computer Science question and need help to study.

1. Implement a GCD function that takes two arbitrarily large integers and outputs their GCD. You are not allowed to use gcd library function. YOu can use any programming language of your choice.

2. Implement the exponentiation function discussed in the class.

3. Implement a primality testing function. YOu can pick whatever method you like to test the primality of a number. Your function should outpute true if the number is a prime number otherwise it returns false.

You can test these functions in a single program by calling these functions from the main program.