A$.$ Consider a variant of DSA algorithm, in which the second component of the signature

generation is computed as

$s=k^{-1}(m+x*r)modq$

Show that this variant is not secure$,$ in which the attacker can forge valid signature for

any arbitrary message of it choice without querying any signatures from the signer.

B$.$ Sony PS$3$ was hacked by the hacker group "fail$0$Overflow" via a key recovery attack on

the ECDSA digital signatures computed in Sony PS$3$ platform. Explain what caused the

attack and show the steps of the attack in details.