In El-Gamal Algorithm, the public key is (p, g, A)$(p, g, A)$, and the secret key is (a)$(a)$, in order to encrypt some data, the sender generate a random k$k$, where: (C1, C2) = (m.A^k (mod p), g^k (mod p))$(C_1, C_2) = (m.A^{k} \pmod{p}, g^{k} \pmod{p})$ If a hacker know the value of k$k$, should this break the algorithm security ?