I have been studying how ElGamal is a public-key algorithm built on top of the Diffie-Hellman key exchange but I got confused. How exactly could an attacker break the Diffie-Hellman protocol (i.e. compute $g^{ab} \bmod p$ efficiently given $p, \space g, \space g^a \bmod p$, and $g^b \bmod p$) if they can efficiently find the plaintext messages from their ciphertexts (encrypted using ElGamal)?
Asked
Active
Viewed 425 times
