Updating existing TX size limit test for the new DKG parameters

coordinator/src/tests/tributary/mod.rs

@@ -84,23 +84,25 @@ fn tx_size_limit() {
  use tributary::TRANSACTION_SIZE_LIMIT;
 
  let max_dkg_coefficients = (MAX_KEY_SHARES_PER_SET * 2).div_ceil(3) + 1;
- let max_key_shares_per_individual = MAX_KEY_SHARES_PER_SET - max_dkg_coefficients;
- // Handwave the DKG Commitments size as the size of the commitments to the coefficients and
- // 1024 bytes for all overhead
- let handwaved_dkg_commitments_size = (max_dkg_coefficients * MAX_KEY_LEN) + 1024;
- assert!(
- u32::try_from(TRANSACTION_SIZE_LIMIT).unwrap() >=
- (handwaved_dkg_commitments_size * max_key_shares_per_individual)
- );
-
- // Encryption key, PoP (2 elements), message
- let elements_per_share = 4;
- let handwaved_dkg_shares_size =
- (elements_per_share * MAX_KEY_LEN * MAX_KEY_SHARES_PER_SET) + 1024;
- assert!(
- u32::try_from(TRANSACTION_SIZE_LIMIT).unwrap() >=
- (handwaved_dkg_shares_size * max_key_shares_per_individual)
- );
+ // n coefficients
+ // 2 ECDH values per recipient, and the encrypted share
+ let elements_outside_of_proof = max_dkg_coefficients + ((2 + 1) * MAX_KEY_SHARES_PER_SET);
+ // Then Pedersen Vector Commitments for each DH done, and the associated overhead in the proof
+ // It's handwaved as one commitment per DH, where we do 2 per coefficient and 1 for the explicit
+ // ECDHs
+ let vector_commitments = (2 * max_dkg_coefficients) + (2 * MAX_KEY_SHARES_PER_SET);
+ // Then we have commitments to the `t` polynomial of length 2 + 2 nc, where nc is the amount of
+ // commitments
+ let t_commitments = 2 + (2 * vector_commitments);
+ // The remainder of the proof should be ~30 elements
+ let proof_elements = 30;
+
+ let handwaved_dkg_size =
+ ((elements_outside_of_proof + vector_commitments + t_commitments + proof_elements) *
+ MAX_KEY_LEN) +
+ 1024;
+ // Further scale by two in case of any errors in the above
+ assert!(u32::try_from(TRANSACTION_SIZE_LIMIT).unwrap() >= (2 * handwaved_dkg_size));
 }
 
 #[test]