Particle Network - MPC Audit

The `comm_witness` parameter is passed to the `EphKeyGenSecondMsg::verify_and_decommit` and `KeyGenSecondMsg::verify_and_decommit` but it is not necessary for any operation connected to the proof verification. The parameter may be misleading for any library user as an information which is unnecessary in respect to the function name semantic needs to be provided.

The audited codebase represents the implementation of scientific papers, however, the variable's names differ from the paper's notation reducing the code readability.

The key generation of the Paillier Scheme produces a public key of bit length 2048. In the `verify_ni_proof_correct_key` of `party_two.rs`, the length of the public key is required to be larger than 2046 to not return an `Err`. ```rust const PAILLIER_KEY_SIZE: usize = 2048; ... if ek.n.bit_length() < PAILLIER_KEY_SIZE - 1 ```

During the construction of the proof `PDLwSlackProof`, Party 1 constructs the following values via the function `generate_h1_h2_n_tilde`: - $\tilde{N}$ which is the product of two safe primes `dk_tilde.p` and `dk_tilde.q`; - the values $h_1$ and $h_2$ in the group $Z_{\tilde{N}}$. The soundness of the proof is dependent on the strong RSA assumption on the modulus $\tilde{N}$. However there is no guarantee that the primes `dk_tilde.p` and `dk_tilde.q` are safe. This condition is referenced in the file [zk_pdl_with_slack/mod.rs](https://reitermk.github.io/papers/2001/CRYPTO.pdf).