Can You Retain Credit Card Numbers in Your Company? A Guide to PCI DSS v4.0 Requirement 3.5.1

We are often asked this question and the companies often wonder: Can we legally and securely retain credit card numbers? The answer is yes—but only under strict conditions defined by the Payment Card Industry Data Security Standard (PCI DSS) version 4.0, specifically Requirement 3.5.1.

Let’s break down what this requirement means and how your company can stay compliant while handling sensitive cardholder data.

🔍 What Is PCI DSS Requirement 3.5.1?

Requirement 3.5.1 mandates that Primary Account Numbers (PANs) must be rendered unreadable wherever they are stored. This is a critical security measure to protect cardholder data from unauthorized access and breaches.

✅ Approved Methods to Render PAN Unreadable:

1. One-Way Hashing

   • Uses strong cryptography to irreversibly transform the entire PAN.
   • Useful for environments where PANs are used for comparison, not retrieval.

2. Truncation

   • Stores only part of the PAN (e.g., first six and last four digits).
   • Important: Hashing cannot be used to replace truncated segments.
   • If multiple formats (e.g., hashed and truncated) exist, additional controls must prevent reconstruction of the full PAN.

3. Index Tokens

   • Replaces PAN with a secure token that maps back to the original via a protected lookup system.
   • Common in tokenization systems for recurring billing or analytics.

4. Strong Encryption

   • Encrypts PAN using robust cryptographic algorithms.
   • Requires secure key management, including access control, rotation, and storage policies.

🏢 Can Your Company Retain Credit Card Numbers?

Yes, but only if:

• You have a legitimate business need (e.g., recurring payments, fraud detection).
• You use one of the approved methods to render PAN unreadable.
• You implement strong access controls and monitoring.
• You do not store Sensitive Authentication Data (SAD) after authorization (e.g., CVV, PIN, magnetic stripe data).

⚠️ Risks of Non-Compliance

Failing to comply with Requirement 3.5.1 can result in:

• Data breaches
• Fines from card brands
• Loss of customer trust
• Legal and regulatory penalties

🛡️ Best Practices for PAN Storage

• Minimize storage: Only retain PANs when absolutely necessary.
• Encrypt and mask: Use strong encryption and display only permitted digits.
• Secure keys: Protect cryptographic keys with strict access and audit controls.
• Regular audits: Review and update your data protection policies frequently.

✅ Final Thoughts

Retaining credit card numbers is possible—but it’s a responsibility that demands rigorous security practices. PCI DSS v4.0 Requirement 3.5.1 provides a clear framework for how PANs must be protected. If your company chooses to store this data, ensure full compliance to safeguard your customers and your reputation.

Call us anytime or email us for your compliance requirements cheers