Pci Compliance

When to use this skill

Use Pci Compliance when an AI agent needs a reusable SKILL.md workflow for this job: 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.

When not to use it

Skip Pci Compliance when the task is outside the coding category, or when a more specific skill in this directory already covers the same workflow with clearer triggers.

How to install

1. Personal install: create ~/.claude/skills/pci-compliance/SKILL.md (and any bundled scripts) so Claude Code, Claude Desktop, and compatible agents can load it in every project.
2. Project install: commit the same folder at .claude/skills/pci-compliance/ so teammates get the skill with the repo.
3. Restart the agent session after copying files so it re-scans the skills directory, then ask for the task in words that match the skill description.

Full install guide for Claude, Cursor, and Codex

What this skill does

# 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) ```

## Additional patterns and templates

More detailed templates and worked examples live in `references/details.md`. Read that file for the full pattern library.

Intended uses

• 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