Multiple (RSA) public key encryption how to verify others received the same information? Non-deterministic encryption I have an RSA system between multiple parties. Alice takes the targets (Bob and Oliver) public keys and encrypts a message using them and sends it to them. All parties know each other's public keys and the ciphertexts received.

I wanted to verify that all the targets are receiving the same message, so I thought Bob could take Oliver's public key and encrypt the received message(after decrypting with his own private key) and compare it but I'm using non-deterministic encryption, therefore, the ciphers produced are different for the same message and public key.

I know using deterministic encryption prone to attacks so I was wondering if there are any other solutions out there or do I have to risk using deterministic. For reference, I'm using JavaScript and AES for encryption. 

How do I verify that Oliver and Bob receive the same message without them having to send it to each other?
As long as you are not wedded to RSA, here's a way that completely solves the problem (and scales to more than two targets).

The general idea is that we do EC-ElGamal in a pairing friendly curve (that is, an elliptic curve that has a computable function $e(X, Y)$ that satisfies the identity $e(aG, bG) = e(G, G)^{ab}$, for any integers $a, b$ (and $G$ is the generator point), and for which $e(G, G) \ne 1$.  The power on the right is typically a multiplicative group of a finite field (which would depend on the curve you're using), that's not important at this point.

In any case, Bob and Oliver would select private keys $b$ and $c$ (I'll use c rather than o for Oliver, because o is too easily confused with 0), and their public keys are $B = bG$ and $C = cG$.

The encrypt, Alice takes the message $m$, and maps it in a way that is both invertable and nondeterministic to a point $M$ (it has to be nondeterministic, otherwise a third party with a guess of $m$ can verify his guess using the $e$ function).  Then, she selects a random value $r$, and generates the two ciphertexts:

$$rG, rB + M$$

$$rG, rC + M$$

(note: each ciphertext can use the same $rG$ value, or use different ones; both varieties work).

Bob and Oliver first check whether all the points in the ciphertexts are actually points in the curve (I'm not sure what can go wrong if they're not, but it's an easy check to do).

Then, Bob can decrypt his received ciphertext $X, Y$ by computing $M = Y - bX$ and then mapping $M$ back to the original $m$.

Bob can then verify that Oliver got the same message by reconstructing $rC$ (using the value $M$ he got during decryption), and then verifying that $e( G, rC ) = e( rG, C )$ (where $rG$ is the value from Oliver's ciphertext); if they received the same message, then both values are $e( G, G )^{rc}$