How would having multiple independently encrypted versions of the same plaintext impact confidentiality?

Question

Suppose I have some unknown plaintext P which I encrypt N times, each time with a completely new and random key and IV. Would knowing that all the encrypted output came from the same identical plaintext make it any easier to guess or derive the original message without any of the keys or IVs? If so, why and how much easier would it get as N became larger?

Answer 1

If the encryption method in question is considered secure today, this will not be an issue.

To be considered secure, an encryption method today needs to be at least indistinguishable under chosen plaintext attack, short IND-CPA. Very informally: This is a game, where the attacker can choose 2 messages, then receives one ciphertext and has to guess which message it was. If the attacker has a probability better than just guessing randomly (more than a negligible amount), the attacker wins and the encryption us considered insecure.

The attacker in that game could just create of course a large amount of encryptions with new keys of his two messages. If that would lead to any type of advantage he could use this to win the game described previously. And that cipher is considered broken in today's world.

So if the encryption is at least IND-CPA, this will not be a problem.