Evaluate a transaction

Portal integrates with Blockaid to provide transaction security evaluation. This allows you to scan transactions for potential security risks before sending them, helping to identify malicious contracts, phishing attempts, and other threats.

Transaction Evaluation

The evaluateTransaction method analyzes a transaction and returns a risk assessment.

Basic Evaluation

import 'package:portal_flutter/portal_flutter.dart';

final portal = Portal();

// Evaluate a transaction before sending
final result = await portal.evaluateTransaction(
  chainId: 'eip155:1',
  to: '0xContractAddress',
  value: '0x0',
  data: '0xa9059cbb...', // Contract call data
);

print('Result: ${result.result}');
print('Classification: ${result.classification}');
print('Reason: ${result.reason}');
print('Description: ${result.description}');

Full Transaction Evaluation

For complete transaction parameters:

final result = await portal.evaluateTransaction(
  chainId: 'eip155:1',
  to: '0xContractAddress',
  from: '0xYourAddress',
  value: '0x10',
  data: '0x',
  gas: '0x5208',
  maxFeePerGas: '0x3B9ACA00',
  maxPriorityFeePerGas: '0x3B9ACA00',
  operationType: PortalEvaluateTransactionOperationType.all,
);

Operation Types

You can specify what type of evaluation to perform:

Operation Type	Description
`validation`	Only validate the transaction structure and parameters
`simulation`	Only simulate the transaction execution
`all`	Perform both validation and simulation

// Validation only
final validationResult = await portal.evaluateTransaction(
  chainId: 'eip155:1',
  to: '0xContractAddress',
  operationType: PortalEvaluateTransactionOperationType.validation,
);

// Simulation only
final simulationResult = await portal.evaluateTransaction(
  chainId: 'eip155:1',
  to: '0xContractAddress',
  operationType: PortalEvaluateTransactionOperationType.simulation,
);

Evaluating Before Sending

A common pattern is to evaluate a transaction before sending it:

import 'package:portal_flutter/portal_flutter.dart';

final portal = Portal();

Future<String?> sendWithEvaluation({
  required String chainId,
  required String to,
  required String value,
}) async {
  // First, evaluate the transaction
  final evaluation = await portal.evaluateTransaction(
    chainId: chainId,
    to: to,
    value: value,
    operationType: PortalEvaluateTransactionOperationType.all,
  );

  // Check the risk assessment
  if (evaluation.result == 'Malicious') {
    print('Transaction blocked due to security risks');
    print('Reason: ${evaluation.reason}');
    print('Description: ${evaluation.description}');
    return null;
  }

  if (evaluation.result == 'Warning') {
    print('Warning: ${evaluation.description}');
    // Optionally prompt user to confirm
  }

  // Proceed with the transaction
  final txHash = await portal.sendTransaction(
    chainId: chainId,
    to: to,
    value: value,
  );

  return txHash;
}

Transaction evaluation is a security tool, not a guarantee. Always exercise caution when interacting with unknown contracts.

Understanding Results

The evaluation result includes:

result: The overall assessment (e.g., Benign, Warning, Malicious)
reason: The reason for the assessment
classification: The classification category of the risk
description: A human-readable description of the findings
status: The status of the evaluation

final result = await portal.evaluateTransaction(
  chainId: 'eip155:1',
  to: '0xContractAddress',
);

// Check the result
if (result.result == 'Benign') {
  print('Transaction appears safe');
} else if (result.result == 'Warning') {
  print('Proceed with caution');
  print('Classification: ${result.classification}');
  print('Description: ${result.description}');
} else if (result.result == 'Malicious') {
  print('Transaction blocked');
  print('Reason: ${result.reason}');
}

Related Documentation

evaluateTransaction function reference

Getting Started

SDKs

APIs

Integrations

Resources

Evaluate a transaction

Transaction Evaluation

Basic Evaluation

Full Transaction Evaluation

Operation Types

Evaluating Before Sending

Understanding Results

​Transaction Evaluation

​Basic Evaluation

​Full Transaction Evaluation

​Operation Types

​Evaluating Before Sending

​Understanding Results

Transaction Evaluation

Basic Evaluation

Full Transaction Evaluation

Operation Types

Evaluating Before Sending

Understanding Results