You could intercept their communications and replace the public key one sends with your own, and when the other tries to send a message to the first (to your public key instead of the cat’s) you get access to the message’s contents and then reencrypt it to the correct public key.
You’d need to know how they encode the data in their meows, which is really hard to analyze because the data being encrypted makes it seem like random noise
And then cats have really good ears, so you’d need to be a highly professional parrot or voice actor or something to convince the cat it’s hearing the cat you want it to think it’s hearing with your key in the exchange. Phone speakers wouldn’t be enough
You could do a MITM attack while they exchange public keys
You can’t decrypt anything with the public keys though, wouldn’t work
You could intercept their communications and replace the public key one sends with your own, and when the other tries to send a message to the first (to your public key instead of the cat’s) you get access to the message’s contents and then reencrypt it to the correct public key.
You’d need to know how they encode the data in their meows, which is really hard to analyze because the data being encrypted makes it seem like random noise
And then cats have really good ears, so you’d need to be a highly professional parrot or voice actor or something to convince the cat it’s hearing the cat you want it to think it’s hearing with your key in the exchange. Phone speakers wouldn’t be enough