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dCVV Calculator

Calculate Dynamic Card Verification Value (dCVV) for contactless EMV transactions using PAN, expiry, ATC, and CVK keys

💳 Card Data

13–19 digit card number. Spaces are allowed.

4-digit expiry in YYMM format.

1–4 hex characters (EMV Tag 9F36). Increments per transaction.

🔑 Card Verification Keys

8-byte DES key (16 hex chars).

8-byte DES key (16 hex chars).

How it works: The dCVV (dynamic Card Verification Value) uses the same 2-key Triple DES algorithm as CVV, but replaces the static 3-digit service code with the ATC (Application Transaction Counter) — a value that increments with each contactless transaction.

Data string: The rightmost 12 digits of the PAN (excluding check digit) are concatenated with the expiry (YYMM) and the ATC (converted to decimal, zero-padded to 5 digits), then zero-padded to 32 characters. This is split into two 8-byte blocks: Block A is DES encrypted with CVK-A, XORed with Block B, then 3DES encrypted with CVK-A+CVK-B. The result is decimalized to produce a 3-digit code.

vs. CVV/iCVV: While CVV uses service code 101 and iCVV uses 999, dCVV uses the ATC to generate a unique code per transaction — preventing replay attacks in contactless MSD environments.

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📖 About This Tool

What is the dCVV Calculator?

The dCVV Calculator computes Dynamic Card Verification Values used in contactless EMV transactions. Unlike static CVV, dCVV changes with each transaction using an unpredictable number, preventing replay attacks.

🛠️ How to Use
  1. Enter the CVV keys (Key A and Key B).
  2. Enter the PAN, expiration date, and service code.
  3. Enter the unpredictable number and ATC.
  4. Click Calculate to generate the dCVV.
❓ FAQ

What is dCVV?

dCVV (Dynamic Card Verification Value) is a one-time CVV generated for each contactless transaction using the ATC (Application Transaction Counter) and an unpredictable number. It prevents stolen CVV values from being replayed.