Reduce minimum number of random beacon shares (#20091)

---

## Release notes

Check each box that your changes affect. If none of the boxes relate to
your changes, release notes aren't required.

For each box you select, include information after the relevant heading
that describes the impact of your changes that a user might notice and
any actions they must take to implement updates.

- [ ] Protocol: 
- [ ] Nodes (Validators and Full nodes): 
- [ ] Indexer: 
- [ ] JSON-RPC: 
- [ ] GraphQL: 
- [ ] CLI: 
- [ ] Rust SDK:
- [ ] REST API:

crates/sui-protocol-config/src/lib.rs

@@ -193,6 +193,7 @@ const MAX_PROTOCOL_VERSION: u64 = 68;
 // Version 68: Add G1Uncompressed group to group ops.
 //             Update to Move stdlib.
 //             Enable gas based congestion control with overage.
+//             Further reduce minimum number of random beacon shares.
 
 #[derive(Copy, Clone, Debug, Hash, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
 pub struct ProtocolVersion(u64);
@@ -2916,6 +2917,9 @@ impl ProtocolConfig {
                         Some(3_700_000); // 20% of above
                     cfg.max_txn_cost_overage_per_object_in_commit = Some(u64::MAX);
                     cfg.gas_budget_based_txn_cost_absolute_cap_commit_count = Some(50);
+
+                    // Further reduce minimum number of random beacon shares.
+                    cfg.random_beacon_reduction_lower_bound = Some(500);
                 }
                 // Use this template when making changes:
                 //

crates/sui-protocol-config/src/snapshots/sui_protocol_config__test__Mainnet_version_68.snap

@@ -317,7 +317,7 @@ consensus_bad_nodes_stake_threshold: 20
 max_jwk_votes_per_validator_per_epoch: 240
 max_age_of_jwk_in_epochs: 1
 random_beacon_reduction_allowed_delta: 800
-random_beacon_reduction_lower_bound: 700
+random_beacon_reduction_lower_bound: 500
 random_beacon_dkg_timeout_round: 3000
 random_beacon_min_round_interval_ms: 500
 random_beacon_dkg_version: 1

crates/sui-protocol-config/src/snapshots/sui_protocol_config__test__Testnet_version_68.snap

@@ -317,7 +317,7 @@ consensus_bad_nodes_stake_threshold: 20
 max_jwk_votes_per_validator_per_epoch: 240
 max_age_of_jwk_in_epochs: 1
 random_beacon_reduction_allowed_delta: 800
-random_beacon_reduction_lower_bound: 700
+random_beacon_reduction_lower_bound: 500
 random_beacon_dkg_timeout_round: 3000
 random_beacon_min_round_interval_ms: 500
 random_beacon_dkg_version: 1

crates/sui-protocol-config/src/snapshots/sui_protocol_config__test__version_68.snap

@@ -328,7 +328,7 @@ consensus_bad_nodes_stake_threshold: 20
 max_jwk_votes_per_validator_per_epoch: 240
 max_age_of_jwk_in_epochs: 1
 random_beacon_reduction_allowed_delta: 800
-random_beacon_reduction_lower_bound: 700
+random_beacon_reduction_lower_bound: 500
 random_beacon_dkg_timeout_round: 3000
 random_beacon_min_round_interval_ms: 500
 random_beacon_dkg_version: 1