Diagram showing 3D Secure, Half 3D Secure, and Non-3D Secure transaction flows based on VERes and PARes response codes

A Half 3D Secure transaction is, in short, the term used when the merchant supports 3D Secure transactions but the card does not.

Can such transactions occur as 3D Secure/Half Secure when the merchant does not support 3D Secure transactions?

A transaction initiated by the merchant without running the 3D process is treated as Non-Secure.

Let's explain 3D Secure, Half 3D Secure, and non-3D Secure transactions based on the Visa VERes, PARes, and ECI (Electronic Commerce Indicator) codes:

VEResDescriptionPAResDescription3D/Half 3D/Non 3DECI
YAuthentication AvailableYAuthentication Successful3D Secure5
YAuthentication AvailableAAttempts Processing PerformedHalf 3D6
YAuthentication AvailableUAuthentication Could Not Be PerformedNon 3D7
YAuthentication AvailableNAuthentication Failed, Merchant should not submit Auth RequestNon 3D7
Error MessageNon 3D7
Validation Of signature or critical fields failedNon 3D7
NCardholder Not ParticipatingHalf 3D6
UNon 3D7
Critical Field Validation FailedNon 3D7
Error MessageNon 3D7

In the VERes message produced as a result of the VEReq message;

  • If the VERes value is anything other than Y or N, the transaction is treated as a non-3D Secure transaction (ECI=7).
  • If the VERes value is N, the transaction is treated as Half 3D Secure.
  • If the VERes value is Y;
    • The PAReq message is sent. The PARes value produced as a response to the PAReq message;
      • If the PARes value is Y; 3D Secure transaction
      • If the PARes value is A; Half 3D Secure transaction
      • If the PARes value is U; it is treated as a non-3D Secure transaction.
      • If the PARes value is N, is erroneous, or signature validation fails, the transaction is included in the authorization flow by the merchant.

You can find details on how the 3D Secure level of a transaction is determined in the article below.

https://arifunal.com/yazi/bir-islemin-3d-secure-yari-3d-ya-da-non-3d3dsiz-oldugu-nasil-belirlenir/