feat: add stateless vn reg utxo validation rules and merkle root

base_layer/core/src/chain_storage/blockchain_backend.rs

@@ -193,8 +193,12 @@ pub trait BlockchainBackend: Send + Sync {
     /// Fetches all tracked reorgs
     fn fetch_all_reorgs(&self) -> Result<Vec<Reorg>, ChainStorageError>;
 
+    /// Fetches the validator node set for the given height ordered according to height of registration and canonical
+    /// block body ordering.
     fn fetch_active_validator_nodes(&self, height: u64) -> Result<Vec<(PublicKey, [u8; 32])>, ChainStorageError>;
+    /// Returns the shard key for the validator node if valid at the given height.
     fn get_shard_key(&self, height: u64, public_key: PublicKey) -> Result<Option<[u8; 32]>, ChainStorageError>;
+    /// Returns all template registrations within (inclusive) the given height range.
     fn fetch_template_registrations(
         &self,
         start_height: u64,

base_layer/core/src/chain_storage/blockchain_database.rs

@@ -38,6 +38,7 @@ use tari_common_types::{
     chain_metadata::ChainMetadata,
     types::{BlockHash, Commitment, FixedHash, HashOutput, PublicKey, Signature},
 };
+use tari_crypto::hash::blake2::Blake256;
 use tari_mmr::pruned_hashset::PrunedHashSet;
 use tari_utilities::{epoch_time::EpochTime, hex::Hex, ByteArray};
 
@@ -814,7 +815,7 @@ where B: BlockchainBackend
             header.timestamp = median_timestamp.increase(1);
         }
         let mut block = Block { header, body };
-        let roots = calculate_mmr_roots(&*db, &block)?;
+        let roots = calculate_mmr_roots(&*db, self.rules(), &block)?;
         block.header.kernel_mr = roots.kernel_mr;
         block.header.kernel_mmr_size = roots.kernel_mmr_size;
         block.header.input_mr = roots.input_mr;
@@ -835,7 +836,7 @@ where B: BlockchainBackend
             block.body.is_sorted(),
             "calculate_mmr_roots expected a sorted block body, however the block body was not sorted"
         );
-        let mmr_roots = calculate_mmr_roots(&*db, &block)?;
+        let mmr_roots = calculate_mmr_roots(&*db, self.rules(), &block)?;
         Ok((block, mmr_roots))
     }
 
@@ -1240,7 +1241,11 @@ impl std::fmt::Display for MmrRoots {
 
 #[allow(clippy::too_many_lines)]
 #[allow(clippy::similar_names)]
-pub fn calculate_mmr_roots<T: BlockchainBackend>(db: &T, block: &Block) -> Result<MmrRoots, ChainStorageError> {
+pub fn calculate_mmr_roots<T: BlockchainBackend>(
+    db: &T,
+    rules: &ConsensusManager,
+    block: &Block,
+) -> Result<MmrRoots, ChainStorageError> {
     let header = &block.header;
     let body = &block.body;
 
@@ -1341,9 +1346,27 @@ pub fn calculate_mmr_roots<T: BlockchainBackend>(db: &T, block: &Block) -> Resul
 
     output_mmr.compress();
 
-    let mut validator_nodes = db.fetch_active_validator_nodes(metadata.height_of_longest_chain() + 1)?;
-    validator_nodes.sort();
-    let vn_mmr = ValidatorNodeMmr::new(validator_nodes.iter().map(|vn| vn.1.to_vec()).collect());
+    let next_height = metadata.height_of_longest_chain() + 1;
+    let epoch_len = rules.consensus_constants(next_height).epoch_length();
+    let validator_node_mr = if next_height % epoch_len == 0 {
+        // At epoch boundary, the MR is rebuilt from the current validator set
+        let validator_nodes = db.fetch_active_validator_nodes(next_height)?;
+        fn hash_node((pk, s): &(PublicKey, [u8; 32])) -> Vec<u8> {
+            use digest::Digest;
+            Blake256::new()
+                .chain(pk.as_bytes())
+                .chain(s.as_slice())
+                .finalize()
+                .to_vec()
+        }
+
+        let vn_mmr = ValidatorNodeMmr::new(validator_nodes.iter().map(hash_node).collect());
+        FixedHash::try_from(vn_mmr.get_merkle_root()?)?
+    } else {
+        // MR is unchanged except for epoch boundary
+        let tip_header = db.fetch_tip_header()?;
+        tip_header.header().validator_node_mr
+    };
 
     let mmr_roots = MmrRoots {
         kernel_mr: FixedHash::try_from(kernel_mmr.get_merkle_root()?)?,
@@ -1352,7 +1375,7 @@ pub fn calculate_mmr_roots<T: BlockchainBackend>(db: &T, block: &Block) -> Resul
         output_mr: FixedHash::try_from(output_mmr.get_merkle_root()?)?,
         output_mmr_size: output_mmr.get_leaf_count() as u64,
         witness_mr: FixedHash::try_from(witness_mmr.get_merkle_root()?)?,
-        validator_node_mr: FixedHash::try_from(vn_mmr.get_merkle_root()?)?,
+        validator_node_mr,
     };
     Ok(mmr_roots)
 }

base_layer/core/src/chain_storage/lmdb_db/cursors.rs

@@ -65,26 +65,6 @@ where V: DeserializeOwned
         }
     }
 
-    // /// Returns the item on or before the given seek key, progressing backwards until the key prefix no longer
-    // matches #[allow(dead_code)]
-    // pub fn prev(&mut self) -> Result<Option<(Vec<u8>, V)>, ChainStorageError> {
-    //     if !self.has_seeked {
-    //         let prefix_key = self.prefix_key;
-    //         if let Some((k, val)) = self.seek_gte(prefix_key)? {
-    //             // seek_range_k returns the greater key, so we only want to return the current value that was seeked
-    // to             // if it exactly matches the prefix_key
-    //             if k == prefix_key {
-    //                 return Ok(Some((k, val)));
-    //             }
-    //         }
-    //     }
-    //
-    //     match self.cursor.prev(&self.access).to_opt()? {
-    //         Some((k, v)) => Self::deserialize_if_matches(self.prefix_key, k, v),
-    //         None => Ok(None),
-    //     }
-    // }
-
     // This function could be used later in cases where multiple seeks are required.
     #[cfg(test)]
     pub fn reset_to(&mut self, prefix_key: &'a [u8]) {
@@ -116,63 +96,6 @@ where V: DeserializeOwned
     }
 }
 
-// pub struct LmdbRangeCursor<'a, K, V> {
-//     cursor: LmdbReadCursor<'a, V>,
-//     start_key: Option<K>,
-//     end_key: Option<K>,
-//     inclusive: bool,
-// }
-//
-// impl<'a, K: Copy, V> LmdbRangeCursor<'a, K, V> {
-//     pub(super) fn new<R: RangeBounds<K>>(cursor: LmdbReadCursor<'a, V>, range: R) -> Self {
-//         Self {
-//             cursor,
-//             start_key: match range.start_bound() {
-//                 Bound::Included(k) | Bound::Excluded(k) => Some(*k),
-//                 Bound::Unbounded => None,
-//             },
-//             end_key: match range.end_bound() {
-//                 Bound::Included(k) |
-//                 Bound::Excluded(k) => Some
-//                 Bound::Unbounded => {}
-//             },
-//             inclusive,
-//         }
-//     }
-//
-//     /// Returns the item on or after the start key, progressing forwards until the end key is reached
-//     pub fn next(&mut self) -> Result<Option<(K, V)>, ChainStorageError>
-//     where K: DeserializeOwned {
-//         let (k, v) = match self.cursor.next()? {
-//             Some(r) => r,
-//             None => return Ok(None),
-//         };
-//         let key = deserialize::<K>(&k)?;
-//         if let Some(end_key) = &self.end_key {
-//             if key > *end_key {
-//                 return Ok(None);
-//             }
-//         }
-//         Ok(Some((key, v)))
-//     }
-//
-//     /// Returns the item on or before the end key, progressing backwards until the start key is reached
-//     pub fn prev(&mut self) -> Result<Option<(K, V)>, ChainStorageError>
-//     where K: DeserializeOwned {
-//         let (k, v) = match self.cursor.prev()? {
-//             Some(r) => r,
-//             None => return Ok(None),
-//         };
-//         let key = deserialize::<K>(&k)?;
-//         if let Some(start_key) = &self.start_key {
-//             if key < *start_key {
-//                 return Ok(None);
-//             }
-//         }
-//         Ok(Some((key, v)))
-//     }
-// }
-
 pub struct LmdbReadCursor<'a, V> {
     cursor: Cursor<'a, 'a>,
     value_type: PhantomData<V>,

base_layer/core/src/chain_storage/lmdb_db/lmdb_db.rs

@@ -1320,7 +1320,7 @@ impl LMDBDatabase {
                 .as_ref()
                 .and_then(|f| f.validator_node_registration())
             {
-                self.insert_validator_node(txn, &block_hash, &vn_reg, mmr_count)?;
+                self.insert_validator_node(txn, &header, output_hash, &vn_reg)?;
             }
             if let Some(template_reg) = output
                 .features
@@ -1402,6 +1402,7 @@ impl LMDBDatabase {
         &self,
         txn: &WriteTransaction<'_>,
         header: &BlockHeader,
+        output_hash: HashOutput,
         vn_reg: &ValidatorNodeRegistration,
     ) -> Result<(), ChainStorageError> {
         let store = self.validator_node_store(txn);

base_layer/core/src/chain_storage/lmdb_db/validator_node_store.rs

@@ -183,6 +183,9 @@ impl<'a, Txn: Deref<Target = ConstTransaction<'a>>> ValidatorNodeStore<'a, Txn>
         let mut cursor = self.index_read_cursor()?;
         let key = ShardIdIndexKey::try_from_parts(&[public_key.as_bytes(), &start_height.to_be_bytes()])
             .expect("fetch_shard_key: Composite key length is incorrect");
+
+        // TODO: unused_assignments is a false positive, we might be able to remove this exclusion in future
+        #[allow(unused_assignments)]
         let mut shard_key = None;
         // Find the first entry at or above start_height
         match cursor.seek_range::<ShardIdIndexKey>(&key.as_bytes())? {

base_layer/core/src/consensus/consensus_constants.rs

@@ -304,6 +304,14 @@ impl ConsensusConstants {
         self.vn_registration_shuffle_interval
     }
 
+    pub fn validator_node_registration_min_deposit_amount(&self) -> MicroTari {
+        self.vn_registration_min_deposit_amount
+    }
+
+    pub fn validator_node_registration_min_lock_height(&self) -> u64 {
+        self.vn_registration_lock_height
+    }
+
     /// Returns the current epoch from the given height
     pub fn block_height_to_current_epoch(&self, height: u64) -> VnEpoch {
         VnEpoch(height / self.vn_epoch_length)

base_layer/core/src/transactions/transaction_components/output_features.rs

@@ -126,6 +126,12 @@ impl OutputFeatures {
         }
     }
 
+    pub fn validator_node_registration(&self) -> Option<&ValidatorNodeRegistration> {
+        self.sidechain_feature
+            .as_ref()
+            .and_then(|s| s.validator_node_registration())
+    }
+
     pub fn is_coinbase(&self) -> bool {
         matches!(self.output_type, OutputType::Coinbase)
     }

base_layer/core/src/transactions/transaction_components/transaction_output.rs

@@ -223,8 +223,7 @@ impl TransactionOutput {
             .as_ref()
             .and_then(|f| f.validator_node_registration())
         {
-            // TODO: figure out what the validator node should sign
-            if !validator_node_reg.is_valid_signature_for(b"") {
+            if !validator_node_reg.is_valid_signature_for(self.commitment.as_bytes()) {
                 return Err(TransactionError::InvalidSignatureError(
                     "Validator node signature is not valid!".to_string(),
                 ));

base_layer/core/src/validation/block_validators/body_only.rs

@@ -87,7 +87,7 @@ impl<B: BlockchainBackend> PostOrphanBodyValidation<B> for BodyOnlyValidator {
             "Block validation: All inputs, outputs and kernels are valid for {}",
             block_id
         );
-        let mmr_roots = chain_storage::calculate_mmr_roots(backend, block.block())?;
+        let mmr_roots = chain_storage::calculate_mmr_roots(backend, &self.rules, block.block())?;
         helpers::check_mmr_roots(block.header(), &mmr_roots)?;
         trace!(
             target: LOG_TARGET,

base_layer/core/src/validation/error.rs

@@ -30,7 +30,10 @@ use crate::{
     chain_storage::ChainStorageError,
     covenants::CovenantError,
     proof_of_work::{monero_rx::MergeMineError, PowError},
-    transactions::transaction_components::{OutputType, TransactionError},
+    transactions::{
+        tari_amount::MicroTari,
+        transaction_components::{OutputType, TransactionError},
+    },
 };
 
 #[derive(Debug, Error)]
@@ -136,6 +139,12 @@ pub enum ValidationError {
     FixedHashSizeError(#[from] FixedHashSizeError),
     #[error("Validator node MMR is not correct")]
     ValidatorNodeMmmrError,
+    #[error("Validator registration has invalid minimum amount {actual}, must be at least {min}")]
+    ValidatorNodeRegistrationMinDepositAmount { min: MicroTari, actual: MicroTari },
+    #[error("Validator registration has invalid maturity {actual}, must be at least {min}")]
+    ValidatorNodeRegistrationMinLockHeight { min: u64, actual: u64 },
+    #[error("Validator node registration signature failed verification")]
+    InvalidValidatorNodeSignature,
 }
 
 // ChainStorageError has a ValidationError variant, so to prevent a cyclic dependency we use a string representation in

base_layer/core/src/validation/helpers.rs

@@ -30,6 +30,7 @@ use tari_crypto::{
     tari_utilities::{epoch_time::EpochTime, hex::Hex},
 };
 use tari_script::TariScript;
+use tari_utilities::ByteArray;
 
 use crate::{
     blocks::{Block, BlockHeader, BlockHeaderValidationError, BlockValidationError},
@@ -824,6 +825,31 @@ pub fn validate_versions(
     Ok(())
 }
 
+pub fn check_validator_node_registration_utxo(
+    consensus_constants: &ConsensusConstants,
+    utxo: &TransactionOutput,
+) -> Result<(), ValidationError> {
+    if let Some(reg) = utxo.features.validator_node_registration() {
+        if utxo.minimum_value_promise < consensus_constants.validator_node_registration_min_deposit_amount() {
+            return Err(ValidationError::ValidatorNodeRegistrationMinDepositAmount {
+                min: consensus_constants.validator_node_registration_min_deposit_amount(),
+                actual: utxo.minimum_value_promise,
+            });
+        }
+        if utxo.features.maturity < consensus_constants.validator_node_registration_min_lock_height() {
+            return Err(ValidationError::ValidatorNodeRegistrationMinLockHeight {
+                min: consensus_constants.validator_node_registration_min_lock_height(),
+                actual: utxo.features.maturity,
+            });
+        }
+
+        if !reg.is_valid_signature_for(utxo.commitment.as_bytes()) {
+            return Err(ValidationError::InvalidValidatorNodeSignature);
+        }
+    }
+    Ok(())
+}
+
 #[cfg(test)]
 mod test {
     use tari_test_utils::unpack_enum;

base_layer/core/src/validation/transaction_validators.rs

@@ -32,6 +32,7 @@ use crate::{
             check_outputs,
             check_permitted_output_types,
             check_total_burned,
+            check_validator_node_registration_utxo,
             validate_versions,
         },
         MempoolTransactionValidation,
@@ -138,6 +139,7 @@ impl<B: BlockchainBackend> MempoolTransactionValidation for TxConsensusValidator
         validate_versions(tx.body(), consensus_constants)?;
         for output in tx.body.outputs() {
             check_permitted_output_types(consensus_constants, output)?;
+            check_validator_node_registration_utxo(consensus_constants, output)?;
         }
         Ok(())
     }