Implement PCI DSS compliance requirements for secure handling of payment card data and payment systems. Use when securing payment processing, achieving PCI compliance, or implementing payment card security measures.
apm install @wshobson/pci-compliance
[](https://apm-p1ls2dz87-atlamors-projects.vercel.app/packages/@wshobson/pci-compliance)---
name: pci-compliance
description: Implement PCI DSS compliance requirements for secure handling of payment card data and payment systems. Use when securing payment processing, achieving PCI compliance, or implementing payment card security measures.
---
# PCI Compliance
Master PCI DSS (Payment Card Industry Data Security Standard) compliance for secure payment processing and handling of cardholder data.
## When to Use This Skill
- Building payment processing systems
- Handling credit card information
- Implementing secure payment flows
- Conducting PCI compliance audits
- Reducing PCI compliance scope
- Implementing tokenization and encryption
- Preparing for PCI DSS assessments
## PCI DSS Requirements (12 Core Requirements)
### Build and Maintain Secure Network
1. Install and maintain firewall configuration
2. Don't use vendor-supplied defaults for passwords
### Protect Cardholder Data
3. Protect stored cardholder data
4. Encrypt transmission of cardholder data across public networks
### Maintain Vulnerability Management
5. Protect systems against malware
6. Develop and maintain secure systems and applications
### Implement Strong Access Control
7. Restrict access to cardholder data by business need-to-know
8. Identify and authenticate access to system components
9. Restrict physical access to cardholder data
### Monitor and Test Networks
10. Track and monitor all access to network resources and cardholder data
11. Regularly test security systems and processes
### Maintain Information Security Policy
12. Maintain a policy that addresses information security
## Compliance Levels
**Level 1**: > 6 million transactions/year (annual ROC required)
**Level 2**: 1-6 million transactions/year (annual SAQ)
**Level 3**: 20,000-1 million e-commerce transactions/year
**Level 4**: < 20,000 e-commerce or < 1 million total transactions
## Data Minimization (Never Store)
```python
# NEVER STORE THESE
PROHIBITED_DATA = {
'full_track_data': 'Magnetic stripe data',
'cvv': 'Card verification code/value',
'pin': 'PIN or PIN block'
}
# CAN STORE (if encrypted)
ALLOWED_DATA = {
'pan': 'Primary Account Number (card number)',
'cardholder_name': 'Name on card',
'expiration_date': 'Card expiration',
'service_code': 'Service code'
}
class PaymentData:
"""Safe payment data handling."""
def __init__(self):
self.prohibited_fields = ['cvv', 'cvv2', 'cvc', 'pin']
def sanitize_log(self, data):
"""Remove sensitive data from logs."""
sanitized = data.copy()
# Mask PAN
if 'card_number' in sanitized:
card = sanitized['card_number']
sanitized['card_number'] = f"{card[:6]}{'*' * (len(card) - 10)}{card[-4:]}"
# Remove prohibited data
for field in self.prohibited_fields:
sanitized.pop(field, None)
return sanitized
def validate_no_prohibited_storage(self, data):
"""Ensure no prohibited data is being stored."""
for field in self.prohibited_fields:
if field in data:
raise SecurityError(f"Attempting to store prohibited field: {field}")
```
## Tokenization
### Using Payment Processor Tokens
```python
import stripe
class TokenizedPayment:
"""Handle payments using tokens (no card data on server)."""
@staticmethod
def create_payment_method_token(card_details):
"""Create token from card details (client-side only)."""
# THIS SHOULD ONLY BE DONE CLIENT-SIDE WITH STRIPE.JS
# NEVER send card details to your server
"""
// Frontend JavaScript
const stripe = Stripe('pk_...');
const {token, error} = await stripe.createToken({
card: {
number: '4242424242424242',
exp_month: 12,
exp_year: 2024,
cvc: '123'
}
});
// Send token.id to server (NOT card details)
"""
pass
@staticmethod
def charge_with_token(token_id, amount):
"""Charge using token (server-side)."""
# Your server only sees the token, never the card number
stripe.api_key = "sk_..."
charge = stripe.Charge.create(
amount=amount,
currency="usd",
source=token_id, # Token instead of card details
description="Payment"
)
return charge
@staticmethod
def store_payment_method(customer_id, payment_method_token):
"""Store payment method as token for future use."""
stripe.Customer.modify(
customer_id,
source=payment_method_token
)
# Store only customer_id and payment_method_id in your database
# NEVER store actual card details
return {
'customer_id': customer_id,
'has_payment_method': True
# DO NOT store: card number, CVV, etc.
}
```
### Custom Tokenization (Advanced)
```python
import secrets
from cryptography.fernet import Fernet
class TokenVault:
"""Secure token vault for card data (if you must store it)."""
def __init__(self, encryption_key):
self.cipher = Fernet(encryption_key)
self.vault = {} # In production: use encrypted database
def tokenize(self, card_data):
"""Convert card data to token."""
# Generate secure random token
token = secrets.token_urlsafe(32)
# Encrypt card data
encrypted = self.cipher.encrypt(json.dumps(card_data).encode())
# Store token -> encrypted data mapping
self.vault[token] = encrypted
return token
def detokenize(self, token):
"""Retrieve card data from token."""
encrypted = self.vault.get(token)
if not encrypted:
raise ValueError("Token not found")
# Decrypt
decrypted = self.cipher.decrypt(encrypted)
return json.loads(decrypted.decode())
def delete_token(self, token):
"""Remove token from vault."""
self.vault.pop(token, None)
```
## Encryption
### Data at Rest
```python
from cryptography.hazmat.primitives.ciphers.aead import AESGCM
import os
class EncryptedStorage:
"""Encrypt data at rest using AES-256-GCM."""
def __init__(self, encryption_key):
"""Initialize with 256-bit key."""
self.key = encryption_key # Must be 32 bytes
def encrypt(self, plaintext):
"""Encrypt data."""
# Generate random nonce
nonce = os.urandom(12)
# Encrypt
aesgcm = AESGCM(self.key)
ciphertext = aesgcm.encrypt(nonce, plaintext.encode(), None)
# Return nonce + ciphertext
return nonce + ciphertext
def decrypt(self, encrypted_data):
"""Decrypt data."""
# Extract nonce and ciphertext
nonce = encrypted_data[:12]
ciphertext = encrypted_data[12:]
# Decrypt
aesgcm = AESGCM(self.key)
plaintext = aesgcm.decrypt(nonce, ciphertext, None)
return plaintext.decode()
# Usage
storage = EncryptedStorage(os.urandom(32))
encrypted_pan = storage.encrypt("4242424242424242")
# Store encrypted_pan in database
```
### Data in Transit
```python
# Always use TLS 1.2 or higher
# Flask/Django example
app.config['SESSION_COOKIE_SECURE'] = True # HTTPS only
app.config['SESSION_COOKIE_HTTPONLY'] = True
app.config['SESSION_COOKIE_SAMESITE'] = 'Strict'
# Enforce HTTPS
from flask_talisman import Talisman
Talisman(app, force_https=True)
```
## Access Control
```python
from functools import wraps
from flask import session
def require_pci_access(f):
"""Decorator to restrict access to cardholder data."""
@wraps(f)
def decorated_function(*args, **kwargs):
user = session.get('user')
# Check if user has PCI access role
if not user or 'pci_access' not in user.get('roles', []):
return {'error': 'Unauthorized access to cardholder data'}, 403
# Log access attempt
audit_log(
user=user['id'],
action='access_cardholder_data',
resource=f.__name__
)
return f(*args, **kwargs)
return decorated_function
@app.route('/api/payment-methods')
@require_pci_access
def get_payment_methods():
"""Retrieve payment methods (restricted access)."""
# Only accessible to users with pci_access role
pass
```
## Audit Logging
```python
import logging
from datetime import datetime
class PCIAuditLogger:
"""PCI-compliant audit logging."""
def __init__(self):
self.logger = logging.getLogger('pci_audit')
# Configure to write to secure, append-only log
def log_access(self, user_id, resource, action, result):
"""Log access to cardholder data."""
entry = {
'timestamp': datetime.utcnow().isoformat(),
'user_id': user_id,
'resource': resource,
'action': action,
'result': result,
'ip_address': request.remote_addr
}
self.logger.info(json.dumps(entry))
def log_authentication(self, user_id, success, method):
"""Log authentication attempt."""
entry = {
'timestamp': datetime.utcnow().isoformat(),
'user_id': user_id,
'event': 'authentication',
'success': success,
'method': method,
'ip_address': request.remote_addr
}
self.logger.info(json.dumps(entry))
# Usage
audit = PCIAuditLogger()
audit.log_access(user_id=123, resource='payment_methods', action='read', result='success')
```
## Security Best Practices
### Input Validation
```python
import re
def validate_card_number(card_number):
"""Validate card number format (Luhn algorithm)."""
# Remove spaces and dashes
card_number = re.sub(r'[\s-]', '', card_number)
# Check if all digits
if not card_number.isdigit():
return False
# Luhn algorithm
def luhn_checksum(card_num):
def digits_of(n):
return [int(d) for d in str(n)]
digits = digits_of(card_num)
odd_digits = digits[-1::-2]
even_digits = digits[-2::-2]
checksum = sum(odd_digits)
for d in even_digits:
checksum += sum(digits_of(d * 2))
return checksum % 10
return luhn_checksum(card_number) == 0
def sanitize_input(user_input):
"""Sanitize user input to prevent injection."""
# Remove special characters
# Validate against expected format
# Escape for database queries
pass
```
## PCI DSS SAQ (Self-Assessment Questionnaire)
### SAQ A (Least Requirements)
- E-commerce using hosted payment page
- No card data on your systems
- ~20 questions
### SAQ A-EP
- E-commerce with embedded payment form
- Uses JavaScript to handle card data
- ~180 questions
### SAQ D (Most Requirements)
- Store, process, or transmit card data
- Full PCI DSS requirements
- ~300 questions
## Compliance Checklist
```python
PCI_COMPLIANCE_CHECKLIST = {
'network_security': [
'Firewall configured and maintained',
'No vendor default passwords',
'Network segmentation implemented'
],
'data_protection': [
'No storage of CVV, track data, or PIN',
'PAN encrypted when stored',
'PAN masked when displayed',
'Encryption keys properly managed'
],
'vulnerability_management': [
'Anti-virus installed and updated',
'Secure development practices',
'Regular security patches',
'Vulnerability scanning performed'
],
'access_control': [
'Access restricted by role',
'Unique IDs for all users',
'Multi-factor authentication',
'Physical security measures'
],
'monitoring': [
'Audit logs enabled',
'Log review process',
'File integrity monitoring',
'Regular security testing'
],
'policy': [
'Security policy documented',
'Risk assessment performed',
'Security awareness training',
'Incident response plan'
]
}
```