PAN in PCI DSS: A Beginner’s Guide to Primary Account Numbers

Introduction

When you hear PAN in PCI DSS, you might wonder what it really means—and why it matters for your business’s security. In this guide, we’ll break down Primary Account Numbers step by step. You’ll learn their structure, why PCI DSS demands strict protection, and the best ways to keep card data safe.

---

What Is PAN in PCI DSS?

Definition of Primary Account Number

• A PAN is the 14–16-digit number printed or embossed on payment cards.
• It comprises three parts:
  1. BIN (Bank Identification Number) – first 6 digits.
  2. Account Identifier – next 7–9 digits.
  3. Check Digit – final digit, for validation.

Table: PAN Structure Example

Segment	Digits	Example	Meaning
Bank ID (BIN)	6	411111	Issuer identifier
Account Identifier	9	111111111	Unique account reference
Check Digit	1	1	Luhn algorithm validation

How PCI DSS Defines and Classifies PAN

• PCI DSS treats PAN as “cardholder data.”
• In-scope elements include:
  • Full PAN value
  • PAN plus cardholder name, expiration date
• Anything that can reconstruct the PAN is also in scope.

---

Why Protecting PAN under PCI DSS Matters

Risks of Exposed PAN

• Financial fraud: Attackers use stolen PANs to make unauthorized charges.
• Identity theft: Fraudsters combine PAN with personal data.
• Regulatory fines: Non-compliance can cost millions.

Relevant PCI DSS Requirements (3 & 4)

Requirement	Focus	Key Point
3	Protect stored PAN	Encrypt, truncate, or tokenize before storage.
4	Encrypt PAN in transit	Use strong TLS when transmitting data.

Real-World Breach Example
In 2013, a major retailer left PANs unencrypted on its servers. Attackers accessed 40 million card numbers. Fines and brand damage followed swiftly.

---

Best Practices for Managing PAN in PCI DSS

Data Encryption & Tokenization

• Encryption: Converts PAN into unreadable cipher.
• Tokenization: Replaces PAN with random tokens.

function tokenizePAN(pan):
    token = secureRandom()
    storeMapping(token, pan)
    return token

Masking and Truncation

• Show only last four digits: **** **** **** 1234.
• Always mask when displaying PAN in UIs or reports.

Access Controls & Monitoring

• Enforce role-based access so only authorized users see PAN.
• Implement logging to track every PAN access.

---

Common Mistakes and FAQs about PAN in PCI DSS

Top 5 Pitfalls

1. Storing full PAN in plain text.
2. Weak encryption keys or outdated algorithms.
3. Ignoring scope—PAN in logs or backups counts.
4. Failing to rotate keys regularly.
5. Omitting regular access reviews.

Frequently Asked Questions

Q1: Is truncated PAN still in scope?
Yes. Even truncated PANs may count if they can be combined with other data to reconstruct the number.

Q2: How often should you rotate encryption keys?
PCI DSS recommends at least annually, after a suspected compromise, or when personnel change roles.

Q3: When is PAN considered out of scope?
Only when it has been irreversibly rendered unrecoverable. Tokenization qualifies; simple hashing may not.

---

Conclusion

You now know exactly what PAN in PCI DSS means, why it demands top-level protection, and how to manage it safely. From encryption to access controls, each step helps you stay compliant and secure.

PCI SSC resources page – https://www.pcisecuritystandards.org/document_library