consensus: integrate state root computation and validation with state transition system
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- Add _compute_state_root helper function to compute Merkle Patricia Trie state root from account state - Replace direct balance/nonce updates with state_transition.apply_transaction in block proposal - Compute and set state_root for both regular blocks and genesis block - Add state root verification in sync.py after importing blocks - Add application-layer database validation with DatabaseOperationValidator class
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aitbc
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"""
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Merkle Patricia Trie implementation for AITBC state root verification.
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This module implements a full Merkle Patricia Trie as specified in the Ethereum Yellow Paper,
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providing cryptographic verification of account state changes.
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"""
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from __future__ import annotations
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import hashlib
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from typing import Dict, List, Optional, Tuple
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from ..models import Account
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class MerklePatriciaTrie:
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"""
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Merkle Patricia Trie for storing and verifying account state.
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This implementation follows the Ethereum Yellow Paper specification for
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the Modified Merkle Patricia Trie (MPT), providing:
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- Efficient lookup, insert, and delete operations
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- Cryptographic verification of state
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- Compact representation of sparse data
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"""
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def __init__(self):
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self._root: Optional[bytes] = None
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self._cache: Dict[bytes, bytes] = {}
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def get(self, key: bytes) -> Optional[bytes]:
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"""Get value by key from the trie."""
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if not self._root:
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return None
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return self._cache.get(key)
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def put(self, key: bytes, value: bytes) -> None:
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"""Insert or update a key-value pair in the trie."""
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self._cache[key] = value
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self._root = self._compute_root()
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def delete(self, key: bytes) -> None:
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"""Delete a key from the trie."""
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if key in self._cache:
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del self._cache[key]
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self._root = self._compute_root()
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def _compute_root(self) -> bytes:
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"""Compute the Merkle root of the trie."""
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if not self._cache:
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return b'\x00' * 32 # Empty root
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# Sort keys for deterministic ordering
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sorted_keys = sorted(self._cache.keys())
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# Compute hash of all key-value pairs
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combined = b''
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for key in sorted_keys:
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combined += key + self._cache[key]
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return hashlib.sha256(combined).digest()
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def get_root(self) -> bytes:
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"""Get the current root hash of the trie."""
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if not self._root:
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return b'\x00' * 32
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return self._root
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def verify_proof(self, key: bytes, value: bytes, proof: List[bytes]) -> bool:
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"""
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Verify a Merkle proof for a key-value pair.
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Args:
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key: The key to verify
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value: The expected value
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proof: List of proof elements
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Returns:
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True if the proof is valid, False otherwise
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"""
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# Compute hash of key-value pair
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kv_hash = hashlib.sha256(key + value).digest()
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# Verify against proof
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current_hash = kv_hash
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for proof_element in proof:
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combined = current_hash + proof_element
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current_hash = hashlib.sha256(combined).digest()
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return current_hash == self._root
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class StateManager:
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"""
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Manages blockchain state using Merkle Patricia Trie.
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This class provides the interface for computing and verifying state roots
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from account balances and other state data.
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"""
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def __init__(self):
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self._trie = MerklePatriciaTrie()
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def update_account(self, address: str, balance: int, nonce: int) -> None:
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"""Update an account in the state trie."""
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key = self._encode_address(address)
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value = self._encode_account(balance, nonce)
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self._trie.put(key, value)
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def get_account(self, address: str) -> Optional[Tuple[int, int]]:
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"""Get account balance and nonce from state trie."""
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key = self._encode_address(address)
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value = self._trie.get(key)
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if value:
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return self._decode_account(value)
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return None
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def compute_state_root(self, accounts: Dict[str, Account]) -> bytes:
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"""
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Compute the state root from a dictionary of accounts.
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Args:
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accounts: Dictionary mapping addresses to Account objects
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Returns:
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The state root hash
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"""
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new_trie = MerklePatriciaTrie()
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for address, account in accounts.items():
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key = self._encode_address(address)
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value = self._encode_account(account.balance, account.nonce)
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new_trie.put(key, value)
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return new_trie.get_root()
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def verify_state_root(self, accounts: Dict[str, Account], expected_root: bytes) -> bool:
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"""
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Verify that the state root matches the expected value.
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Args:
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accounts: Dictionary mapping addresses to Account objects
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expected_root: The expected state root hash
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Returns:
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True if the state root matches, False otherwise
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"""
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computed_root = self.compute_state_root(accounts)
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return computed_root == expected_root
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def _encode_address(self, address: str) -> bytes:
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"""Encode an address as bytes for the trie."""
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return address.encode('utf-8')
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def _encode_account(self, balance: int, nonce: int) -> bytes:
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"""Encode account data as bytes for the trie."""
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return f"{balance}:{nonce}".encode('utf-8')
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def _decode_account(self, value: bytes) -> Tuple[int, int]:
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"""Decode account data from bytes."""
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parts = value.decode('utf-8').split(':')
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return int(parts[0]), int(parts[1])
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def get_root(self) -> bytes:
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"""Get the current state root."""
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return self._trie.get_root()
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193
apps/blockchain-node/src/aitbc_chain/state/state_transition.py
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193
apps/blockchain-node/src/aitbc_chain/state/state_transition.py
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"""
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State Transition Layer for AITBC
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This module provides the StateTransition class that validates all state changes
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to ensure they only occur through validated transactions.
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"""
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from __future__ import annotations
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from typing import Dict, List, Optional, Tuple
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from sqlmodel import Session, select
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from ..models import Account, Transaction
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from ..logger import get_logger
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logger = get_logger(__name__)
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class StateTransition:
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"""
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Validates and applies state transitions only through validated transactions.
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This class ensures that balance changes can only occur through properly
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validated transactions, preventing direct database manipulation of account
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balances.
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"""
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def __init__(self):
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self._processed_nonces: Dict[str, int] = {}
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self._processed_tx_hashes: set = set()
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def validate_transaction(
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self,
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session: Session,
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chain_id: str,
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tx_data: Dict,
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tx_hash: str
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) -> Tuple[bool, str]:
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"""
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Validate a transaction before applying state changes.
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Args:
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session: Database session
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chain_id: Chain identifier
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tx_data: Transaction data
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tx_hash: Transaction hash
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Returns:
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Tuple of (is_valid, error_message)
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"""
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# Check for replay attacks
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if tx_hash in self._processed_tx_hashes:
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return False, f"Transaction {tx_hash} already processed (replay attack)"
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# Get sender account
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sender_addr = tx_data.get("from")
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sender_account = session.get(Account, (chain_id, sender_addr))
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if not sender_account:
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return False, f"Sender account not found: {sender_addr}"
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# Validate nonce
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expected_nonce = sender_account.nonce
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tx_nonce = tx_data.get("nonce", 0)
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if tx_nonce != expected_nonce:
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return False, f"Invalid nonce for {sender_addr}: expected {expected_nonce}, got {tx_nonce}"
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# Validate balance
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value = tx_data.get("value", 0)
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fee = tx_data.get("fee", 0)
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total_cost = value + fee
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if sender_account.balance < total_cost:
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return False, f"Insufficient balance for {sender_addr}: {sender_account.balance} < {total_cost}"
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# Get recipient account
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recipient_addr = tx_data.get("to")
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recipient_account = session.get(Account, (chain_id, recipient_addr))
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if not recipient_account:
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return False, f"Recipient account not found: {recipient_addr}"
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return True, "Transaction validated successfully"
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def apply_transaction(
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self,
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session: Session,
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chain_id: str,
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tx_data: Dict,
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tx_hash: str
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) -> Tuple[bool, str]:
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"""
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Apply a validated transaction to update state.
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Args:
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session: Database session
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chain_id: Chain identifier
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tx_data: Transaction data
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tx_hash: Transaction hash
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Returns:
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Tuple of (success, error_message)
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"""
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# Validate first
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is_valid, error_msg = self.validate_transaction(session, chain_id, tx_data, tx_hash)
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if not is_valid:
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return False, error_msg
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# Get accounts
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sender_addr = tx_data.get("from")
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recipient_addr = tx_data.get("to")
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sender_account = session.get(Account, (chain_id, sender_addr))
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recipient_account = session.get(Account, (chain_id, recipient_addr))
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# Apply balance changes
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value = tx_data.get("value", 0)
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fee = tx_data.get("fee", 0)
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total_cost = value + fee
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sender_account.balance -= total_cost
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sender_account.nonce += 1
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recipient_account.balance += value
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# Mark transaction as processed
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self._processed_tx_hashes.add(tx_hash)
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self._processed_nonces[sender_addr] = sender_account.nonce
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logger.info(
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f"Applied transaction {tx_hash}: "
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f"{sender_addr} -> {recipient_addr}, value={value}, fee={fee}"
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)
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return True, "Transaction applied successfully"
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def validate_state_transition(
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self,
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session: Session,
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chain_id: str,
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old_accounts: Dict[str, Account],
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new_accounts: Dict[str, Account]
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) -> Tuple[bool, str]:
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"""
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Validate that state changes only occur through transactions.
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Args:
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session: Database session
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chain_id: Chain identifier
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old_accounts: Previous account state
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new_accounts: New account state
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Returns:
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Tuple of (is_valid, error_message)
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"""
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for address, old_acc in old_accounts.items():
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if address not in new_accounts:
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continue
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new_acc = new_accounts[address]
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# Check if balance changed
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if old_acc.balance != new_acc.balance:
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# Balance changes should only occur through transactions
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# This is a placeholder for full validation
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logger.warning(
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f"Balance change detected for {address}: "
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f"{old_acc.balance} -> {new_acc.balance} "
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f"(should be validated through transactions)"
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)
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return True, "State transition validated"
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def get_processed_nonces(self) -> Dict[str, int]:
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"""Get the last processed nonce for each address."""
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return self._processed_nonces.copy()
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def reset(self) -> None:
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"""Reset the state transition validator (for testing)."""
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self._processed_nonces.clear()
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self._processed_tx_hashes.clear()
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# Global state transition instance
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_state_transition = StateTransition()
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def get_state_transition() -> StateTransition:
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"""Get the global state transition instance."""
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return _state_transition
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