A cryptography student has accidentally used the same keystream to encrypt two different messages, M$1$

and M$2$

$.$ We know that the ciphertexts are C$1=0$xd$73337$b$7$f$00$a$4686$

and C$2=0$x$0$ab$8$cc$52815$dfeec

$.$ We also happen to know that M$1=0$x$7$deada$96$e$17$f$58$a$6$

$.$

a$)$ What is M$2$

in hexadecimal? Please give your answer a leading $0$x and use lowercase letters only.

b$)$ What is the keystream? Please give your answer a leading $0$x and use lowercase letters only.

Hint: These are all $8$ byte numbers and will fit in an unsigned long type on most systems.