Alice and Bob are using the ElGamal cipher with the parameters p$=101$

and $\backslash$alpha $=2$

$.$

Alice makes the mistake of using the same ephemeral key for two plaintexts, x$1$

and x$2$

$.$ The eavesdropper Eve suspects that x$1=45$

$.$ She sees the two ciphertexts y$1=20$

and y$2=86$

in transit; these are the encryptions of x$1$

and x$2$

$,$ respectively.

a$)$ What is the masking key kM$?$

b$)$ What is the plaintext x$2?$