plaintext attacks

if an attacker can get a Destination to encrypt a large number of messages
to the attacker (so that the attacker has the plaintext and ciphertext),
 at what point will there be effective attacks against the ElGamal private
key?

(I'm not concerned about the AES session key, as that is shared anyway)

Basically, is ElG vulnerable to plaintext attacks?

-jrandom



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