Alice and Bob are using the ElGamal cipher with the parameters $=149$

and $=2$

$.$

Suppose Alice is observed sending public ephemeral key $=142$

and Bob sends public key $=74$

$.$

Their private keys are $=68$

and $=73$

$,$ respectively.

a$)$ What is the masking key $$

$?$

b$)$ What is the encryption of $=133$

$?$vv