$(7)($RSA digital signature$)$ Bob chooses the secret primes $p=5$ and $q=7$ and

the verification exponent $e=11.$

Bob publishes $N=35$ and $e=11.$

$($a$)$ Compute $d$ such that

$de-=1,(mod(p-1)(q-1))$

$($b$)$ Sign the document $D=2$ by computing the signature $S-=D^d(modN).$

$($c$)$ Verify the correctness of the signature by computing $S^e(modN)$