3DS ReferenceProtocol & field guide

EMV 3-D Secure · Core specification 2.3.1.1

How to find required AReq fields in EMV 3DS

There is no single AReq checklist that applies to every transaction. Start with the Authentication Request message, choose the channel and category, then read each conditional requirement in context.

Explore AReq for browser payment authentication

Build a contextual checklist

  1. Open the AReq message reference to see the baseline field inventory.
  2. In the explorer, select the device channel: APP, BRW or 3RI.
  3. Select the message category: payment (PA) or non-payment (NPA).
  4. Inspect both Required and Conditional fields. A conditional field can become required when its condition is met.
  5. Open each relevant field to read its source text, FAQ qualifications, format and allowed values.

Why counts can differ

Channel and category change applicability. Some rules remain unresolved until additional transaction information or programme requirements are known. Contained members and nested object properties are not counted as separate top-level fields.

Baseline inclusion. Effective requirements depend on transaction context. Check the field’s conditions and FAQ qualifications; select channel and category in the explorer.

Keep the source with the answer

A checklist is a reading aid, not proof that an implementation conforms to the protocol. Preserve the chosen context when sharing an explorer URL and check the source and coverage notes.