In Diffie-Hellman key exchange, each user chooses a private X, calculates a public Y, and after exchanging Y, calculates

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In Diffie-Hellman key exchange, each user chooses a private X,
calculates a public Y, and after exchanging Y, calculates K where
for user a: Ya = αXa mod q; Ka= Yb Xa mod q ; q is a prime number;
Xa < q, and α is a primitive root of q (α is sometimes also
referred to g). For example, you and Sarah have agreed to use
values q = 11 and α = 2. You just received a message from Sarah
containing her public value, Yb = 9. You choose a private value Xa
= 8.
(a)What public value(s) will you send to Sarah? Show all
calculations.
(b)What secret K will you create/share with Sarah? Show all
calculations.
(c)What type of value(s) you recommend ensuring Diffie-Hellman
key exchange is secure, i.e. so an attacker cannot determine the
secret shared between you and Sarah?
(d)What is a primitive root of 17?