Why doesn't the attacker have the key? It's a public key cryptosystem, so we should assume the attacker has the public key. The attacker can encrypt all 128 as

Why doesn't the attacker have the key? It's a public key cryptosystem, so we should assume the attacker has the public key. The attacker can encrypt all 128 ascii characters under the public key that was used to encrypt the whole string. The fact that the author was missing (which was pointed out later) was that two encryptions of the same byte under the same key will produce different ciphertexts.