Replace proof of fairness with a PDL with Slack proof from GG18/20

src/add_party_message.rs

@@ -44,7 +44,7 @@ pub struct JoinMessage {
 /// environment variables for each party that they agree on. In this case, each new party generates
 /// it's own DlogStatements and submits it's proofs
 fn generate_h1_h2_n_tilde() -> (BigInt, BigInt, BigInt, BigInt, BigInt) {
-    let (ek_tilde, dk_tilde) = Paillier::keypair().keys();
+    let (ek_tilde, dk_tilde) = Paillier::keypair_with_modulus_size(crate::PAILLIER_KEY_SIZE).keys();
     let one = BigInt::one();
     let phi = (&dk_tilde.p - &one) * (&dk_tilde.q - &one);
     let h1 = BigInt::sample_below(&ek_tilde.n);

src/error.rs

@@ -15,18 +15,28 @@ pub enum FsDkrError {
     #[error("Shares did not pass verification.")]
     PublicShareValidationError,
 
-    #[error("SizeMismatch error for the refresh message {refresh_message_index:?} - Fairness proof length: {fairness_proof_len:?}, Points Commited Length: {points_commited_len:?}, Points Encrypted Length: {points_encrypted_len:?}")]
+    #[error("SizeMismatch error for the refresh message {refresh_message_index:?} - pdl proof length: {pdl_proof_len:?}, Points Commited Length: {points_commited_len:?}, Points Encrypted Length: {points_encrypted_len:?}")]
     SizeMismatchError {
         refresh_message_index: usize,
-        fairness_proof_len: usize,
+        pdl_proof_len: usize,
         points_commited_len: usize,
         points_encrypted_len: usize,
     },
 
-    #[error("Fairness proof verification failed, results - T_add_e_Y == z_G: {t_add_eq_z_g:?} - e_u_add_c_e == enc_z_w: {e_u_add_eq_z_w:?}")]
-    FairnessProof {
-        t_add_eq_z_g: bool,
-        e_u_add_eq_z_w: bool,
+    #[error("PDLwSlack proof verification failed, results: u1 == u1_test: {is_u1_eq:?}, u2 == u2_test: {is_u2_eq:?}, u3 == u3_test: {is_u3_eq:?}")]
+    PDLwSlackProof {
+        is_u1_eq: bool,
+        is_u2_eq: bool,
+        is_u3_eq: bool,
+    },
+
+    #[error("Range Proof failed for party: {party_index:?}")]
+    RangeProof { party_index: usize },
+
+    #[error("The Paillier moduli size of party: {party_index:?} is {moduli_size:?} bits, when it should be 2047-2048 bits")]
+    MouliTooSmall {
+        party_index: usize,
+        moduli_size: usize,
     },
 
     #[error("Paillier verification proof failed for party {party_index:?}")]

src/lib.rs

@@ -16,6 +16,9 @@
 
 pub mod add_party_message;
 pub mod error;
-pub mod proof_of_fairness;
+pub mod range_proofs;
 pub mod refresh_message;
 mod test;
+pub mod zk_pdl_with_slack;
+
+pub(crate) const PAILLIER_KEY_SIZE: usize = 2048;