We take security seriously and actively maintain the following versions:

We appreciate security researchers and users who report vulnerabilities to us. We take all security reports seriously.

Please do NOT report security vulnerabilities through public GitHub issues.

Instead, please report security vulnerabilities by:

1. Email: Send details to the repository maintainers through GitHub (use the "Security" tab if available)
2. Private Issue: If email is not available, create a private security advisory on GitHub

When reporting a vulnerability, please include:

• Description: Clear description of the vulnerability
• Impact: Potential impact and severity
• Steps to Reproduce: Detailed steps to reproduce the issue
• Proof of Concept: If possible, include PoC code
• Suggested Fix: If you have ideas on how to fix it
• Disclosure Timeline: Your expected disclosure timeline

**Vulnerability Type**: [e.g., Authentication Bypass, Code Injection]

**Affected Component**: [e.g., wallet.py, transaction validation]

**Description**:
Detailed description of the vulnerability...

**Impact**:
What an attacker could do with this vulnerability...

**Steps to Reproduce**:
1. Step one
2. Step two
3. See vulnerability

**Proof of Concept**:
```python
# PoC code here

Suggested Fix: Recommendations for fixing the issue...

## Response Timeline

- **Initial Response**: Within 48 hours
- **Confirmation**: Within 7 days
- **Fix Development**: Depends on severity
  - Critical: 1-7 days
  - High: 7-14 days
  - Medium: 14-30 days
  - Low: 30-90 days
- **Public Disclosure**: After fix is released

## Security Best Practices

### For Users

#### Private Key Security

1. **Never share private keys**
   ```python
   # DON'T do this
   print(wallet.export_private_key())  # Logs private key

2. Store private keys securely

   • Use encryption for stored keys
   • Use secure key management systems in production
   • Never commit keys to version control

3. Use environment variables

   import os
   private_key = os.getenv('WALLET_PRIVATE_KEY')

1. Use HTTPS in production

   # Production
   blockchain.register_node('https://node1.example.com')
   
   # Not for production
   blockchain.register_node('http://node1.example.com')

2. Validate node addresses

3. Implement rate limiting on API endpoints

1. Validate all inputs

   def validate_address(address: str) -> bool:
       if not address or not isinstance(address, str):
           return False
       return address.startswith('-----BEGIN PUBLIC KEY-----')

2. Sanitize user inputs

3. Use parameterized queries for database operations

1. Always verify signatures

   if not blockchain.verify_transaction_signature(
       sender_key, signature, transaction
   ):
       raise ValueError("Invalid signature")

2. Check balances before transactions

3. Validate transaction amounts

1. Follow secure coding practices

2. Use static analysis tools

   bandit -r blockchain_core
   safety check

3. Keep dependencies updated

   pip list --outdated
   pip install --upgrade cryptography

1. Use established cryptographic libraries

   • We use cryptography library
   • Don't implement custom crypto

2. Use appropriate key sizes

   • SECP256K1 for ECDSA
   • SHA-256 for hashing

3. Secure random number generation

   from cryptography.hazmat.primitives.asymmetric import ec
   private_key = ec.generate_private_key(ec.SECP256K1())

1. Implement authentication
2. Use CORS appropriately
3. Rate limiting
4. Input validation
5. Error handling (don't leak sensitive info)

1. Use parameterized queries

   cursor.execute(
       'SELECT * FROM blocks WHERE block_index = ?',
       (index,)
   )

2. Encrypt sensitive data

3. Secure database files

This implementation is primarily for educational purposes. For production use:

1. Initial Balance: The default initial balance (150) is for demonstration only
2. Proof of Work: Adjust difficulty for production networks
3. Network Security: Implement proper node authentication
4. Consensus: Consider more advanced consensus mechanisms
5. 51% Attack: Be aware of blockchain security limitations

1. Key Management: Implement proper key management systems
2. Signature Verification: Always verify transaction signatures
3. Hash Functions: SHA-256 is used throughout
4. Random Number Generation: Uses system-secure random

The REST API should be secured with:

• Authentication (JWT, API keys)
• HTTPS in production
• Rate limiting
• Input validation
• CORS configuration

• ✅ ECDSA signature verification
• ✅ Transaction validation
• ✅ Balance checking
• ✅ Chain validation
• ✅ Input sanitization in CLI
• ✅ Type hints for better code safety
• ✅ Error handling throughout
• ✅ Logging for audit trails

• ⏳ JWT authentication for API
• ⏳ Enhanced encryption for stored keys
• ⏳ Rate limiting middleware
• ⏳ Advanced consensus mechanisms
• ⏳ Multi-signature support

# Bandit security linter
bandit -r blockchain_core

# Safety - check dependencies
safety check

# Check for secrets in code
git secrets --scan

# Run security tests
pytest tests/ -m security

• Transaction signature validation
• Balance validation
• Input validation
• SQL injection prevention
• Chain validation

This project aims to follow:

• OWASP Top 10 guidelines
• CWE (Common Weakness Enumeration) standards
• Secure coding best practices

We regularly monitor and update dependencies for security vulnerabilities:

# Check for vulnerabilities
pip-audit

# Update dependencies
pip install --upgrade -r requirements.txt

• We follow responsible disclosure practices
• Security vulnerabilities will be disclosed after fixes are available
• Credit will be given to security researchers who report vulnerabilities

We thank the following security researchers (list will be updated):

No vulnerabilities reported yet

For security concerns, please contact the maintainers through:

• GitHub Security Advisories
• Repository maintainers' GitHub profiles

Remember: Security is everyone's responsibility. If you see something, say something.