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Troubleshooting

Aug 17, 20266 min read

Debugging EMV Offline Data Authentication: DDA, CDA, DDOL and CAPKs

When Offline Data Authentication (ODA) fails, replacing Certification Authority Public Keys (CAPKs) at random is rarely productive. Most field failures sit earlier in the chain: …

Jul 28, 20266 min read

Why an EMV Contact Transaction Was Declined: AAC, TVR and Action Analysis

An EMV contact decline is not a single error. It is the outcome of decisions made by the terminal, the card, or the issuer at different stages of the transaction. Treating …