Visa payWave — EMVCo Kernel 3
Visa payWave (Kernel 3): the TTQ (9F66) / CTQ (9F6C) qVSDC model, with the card returning its decision and cryptogram in the GPO response for a fast tap.
Overview
Kernel 3 is the EMVCo contactless kernel for Visa. It is the canonical user of the Terminal Transaction Qualifiers (9F66): the reader builds the TTQ during pre-processing and passes it in the GPO command.
In qVSDC mode the card returns its Card Transaction Qualifiers (9F6C) and the Application Cryptogram directly in the GPO response, so a low-value tap can complete without reading records. fast DDA provides offline card authentication.
Transaction flow
Visa payWave (Kernel 3). The reader pre-processes the TTQ (9F66), then qVSDC lets the card return its decision and cryptogram directly in the GPO response for a fast tap; fDDA authenticates offline.
1Pre-Processing
build & reset TTQ
Per-AID pre-processing builds the Terminal Transaction Qualifiers (9F66) from terminal config and the contactless limits (floor / CVM-required / no-CVM).
TTQ (9F66) + CTQ (9F6C)
The reader sends the 4-byte TTQ declaring MSD/VSDC/qVSDC support, online-PIN/signature, online-cryptogram and CVM-required bits. The card replies with the 2-byte CTQ telling the reader its CVM and online/offline requirements.
Decode it live: TTQ Decoder (Visa)
Cardholder verification
The reader reads the CTQ: online PIN, on-device CDCVM, signature, or no CVM — evaluated against reader capabilities in the TTQ.
Key data elements
| Tag | Name | Notes |
|---|---|---|
9F66 | Terminal Transaction Qualifiers (TTQ) | Visa qVSDC layout. |
9F6C | Card Transaction Qualifiers (CTQ) | Card CVM / online requirements. |
9F6E | Form Factor Indicator | Visa meaning of 9F6E. |