Re: Encrypting same data with many keys...

So if I wanted to do this and use RSA, how could it be shielded from attack? I take it switching to DH or MH won't help. Would Eliptic Curves have different properties against this attack?

Maybe a random session key in the middle would help?

Using a salt would work. DH would be okay if you used DH to exchange a different key with each recipient and then conventionally encrypted the message with that key. The point is that you need to use different (random) inputs to each P-K operation in order to avoid the possibility of ending up with a system of equations that could be solved.