A PIN is one of the most familiar security mechanisms in payments. Every time a cardholder types a short numeric code into a terminal or ATM, they are proving they are the rightful owner of that card. Despite its simplicity, the PIN remains one of the most effective tools for preventing fraud at the point of sale.
How PIN Works
Cardholder initiates payment
The cardholder inserts, taps, or swipes their card at a payment terminal. The terminal detects the card's capabilities and determines that PIN entry is the required cardholder verification method.
PIN entry on secure device
The terminal prompts the cardholder to enter their PIN on a PIN Entry Device (PED). This hardware contains a tamper-resistant secure cryptographic module that immediately encrypts the PIN the moment each digit is pressed.
PIN block encryption
The PED creates an encrypted PIN block using Triple DES or AES encryption. This block combines the PIN with the card's Primary Account Number to produce a unique encrypted value that cannot be reversed without the correct decryption keys.
Routing to issuer or chip
For an online PIN, the encrypted PIN block is sent through the payment network to the card issuer for verification. For an offline PIN, the encrypted value is sent directly to the EMV chip on the card, which compares it against the stored reference.
Verification and authorization
The issuer (or chip) validates the PIN. If correct, the transaction proceeds to authorization. If incorrect, the cardholder is prompted to retry. After a set number of failures—typically three—the card is locked to prevent guessing attacks.
Why PIN Matters
PIN verification is a cornerstone of payment security worldwide. The data consistently shows its effectiveness:
- 70% fraud reduction: Visa reported that markets transitioning from signature to PIN verification saw fraud at the point of sale drop by up to 70%, making PIN the single most impactful change in card-present security.
- $28.6 billion in global card fraud: According to the Nilson Report (2023), global card fraud losses reached $28.6 billion. Countries with universal PIN adoption—such as France and the UK—consistently report lower per-capita fraud than signature-reliant markets.
- 98.5% of European transactions use PIN as the primary cardholder verification method, according to the European Central Bank's 2023 card fraud report, contributing to Europe's significantly lower fraud-to-transaction ratio compared to other regions.
Global shift
The United States was one of the last major markets to begin adopting PIN for credit card transactions. Major networks eliminated the signature requirement in 2018, accelerating PIN adoption and aligning the U.S. with global security standards.
PIN vs. Signature
| Feature | PIN | Signature |
|---|---|---|
| Authentication type | Something you know | Something you produce |
| Forgery difficulty | Very high — encrypted, limited attempts | Low — signatures are easily imitated |
| Speed at checkout | Fast — typically under 3 seconds | Slower — requires writing and optional staff comparison |
| Fraud liability | Often shifts to issuer when PIN is used correctly | Merchant may bear liability for unverified signatures |
| Supported by EMV | Yes — both online and offline modes | Yes — but increasingly deprecated |
| Two-factor authentication potential | Strong — combines card possession with knowledge factor | Weak — single factor only |
The payment industry has broadly moved toward PIN as the preferred verification method, with most networks now treating signature as a fallback rather than a primary option.
Types of PIN
Online PIN The encrypted PIN block travels across the payment network to the card issuer for real-time verification. This is the most common type in markets with reliable connectivity and provides the highest security because the issuer can cross-reference against known compromised PINs.
Offline PIN (plaintext) The PIN is verified by the chip card itself. The terminal sends the PIN to the chip, which compares it against its stored value. Used primarily as a fallback when network connectivity is unavailable.
Offline PIN (enciphered) Similar to offline plaintext, but the PIN is encrypted before being sent to the chip. This adds a layer of protection against eavesdropping on the communication between the terminal and the card. It is the preferred offline method in high-security environments.
One-Time PIN (OTP) A dynamically generated numeric code sent via SMS or app for card-not-present transactions. While technically different from a traditional card PIN, OTPs serve the same knowledge-based authentication purpose in e-commerce scenarios.
Best Practices
For Merchants
- Use PIN-preferring terminal configurations. Set your terminals to request PIN as the primary CVM whenever the card supports it, rather than defaulting to signature or no-CVM.
- Keep PED firmware updated. PIN Entry Devices receive security patches that address newly discovered vulnerabilities. Outdated firmware can expose your business to compliance issues and breaches.
- Ensure PCI PTS compliance. Only use PIN entry devices that are listed on the PCI Security Standards Council's approved devices list. Expired or unapproved devices must be replaced.
- Train staff to never handle PINs. Employees should never ask a customer for their PIN or assist with entry. If a customer struggles, direct them to contact their bank.
For Developers
- Never log or store PIN data. PIN blocks must never appear in application logs, databases, or error reports. Implement strict controls to ensure encrypted PIN data passes through your system without persistence.
- Use hardware security modules (HSMs) for any PIN translation or validation operations. Software-based PIN handling violates PCI PIN Security requirements and creates serious vulnerability.
- Implement proper PIN block formats. ISO 9564 defines standard PIN block formats (Format 0 through Format 4). Use Format 4 (AES-based) for new implementations to align with current security standards.
- Support both online and offline PIN paths in your payment application to ensure compatibility across card types and network conditions.
Common Mistakes
- Choosing obvious PINs. Research from Data Genetics found that "1234" accounts for nearly 11% of all four-digit PINs. Sequential and repeated-digit codes are the first combinations tested in any attack scenario.
- Reusing the same PIN across multiple cards. If one card is compromised, an attacker may attempt the same PIN on your other accounts. Use a unique PIN for each card.
- Writing the PIN on or near the card. This eliminates the entire security benefit. A stolen wallet then provides both the card and the knowledge factor simultaneously.
- Skipping PIN on low-value transactions. Many merchants configure contactless thresholds to skip PIN verification for small amounts. While convenient, this creates a window for cumulative fraud using stolen cards on many small purchases.
- Ignoring PIN entry device tampering. Merchants who do not regularly inspect terminals for skimming devices or overlays risk having customer PINs captured by criminals.
PIN and Tagada
As a payment orchestration platform, Tagada routes transactions across multiple acquirers and processors while ensuring that PIN verification flows are handled securely end-to-end. Tagada's routing engine respects CVM requirements set by each card and issuer, ensuring PIN-preferring cards are always processed through PIN-capable pathways—regardless of which acquirer is selected for optimal approval rates.