qVSDC Mode Details

[Good Carder]

Overview of qVSDC Mode​

qVSDC, or quick Visa Smart Debit/Credit, is Visa's primary specification for contactless payment transactions using EMV chip technology. It enables secure, proximity-based (tap) payments via NFC/RFID, where the card or device interacts with a reader (Proximity Coupling Device or PCD) without physical insertion. The mode compresses multiple standard EMV commands into fewer exchanges to minimize processing time, typically keeping the total card-in-field interaction under 500 milliseconds. This optimization supports fast checkout in high-throughput environments like retail, quick-service restaurants (QSR), and transit, while maintaining EMV-level security through dynamic cryptograms. All newly issued Visa contactless cards and readers must support qVSDC, and it is the required upgrade path from legacy Magnetic Stripe Data (MSD) contactless modes.

Streamlined qVSDC is a variant that simplifies processing further by making transactions online-only, eliminating some card decision steps, but it appears identical to standard qVSDC from the terminal's perspective. qVSDC aligns with the Visa Contactless Payment Specification (VCPS) and EMV Contactless Specifications, ensuring global interoperability.

Purpose and Key Features​

The primary purpose of qVSDC is to provide a faster, more secure alternative to magnetic stripe or full EMV contact transactions, reducing perceived and actual processing time while enabling issuer-based fraud detection via cryptograms. Key features include:

• Security Enhancements: Uses Authorization Request Cryptogram (ARQC) for online issuer authentication, preventing skimming or counterfeiting. Supports Fast Dynamic Data Authentication (fDDA) for offline-capable scenarios (e.g., transit), which optimizes signature generation early in the flow.
• Speed Optimizations: Allows card removal before final amount or authorization response (via Quick Chip integration), using placeholder amounts if needed. Preliminary processing (e.g., risk checks) occurs before card presentment.
• Flexibility: Supports various form factors (cards, mobiles, wearables) with no processing differences in authorization or clearing. Includes Terminal Transaction Qualifiers (TTQ, tag 9F66) to signal capabilities like Consumer Device Cardholder Verification Method (CDCVM) support.
• Online Focus: In regions like the U.S. (zero-floor-limit), all transactions are online-only, leveraging issuer host-based risk management.

Differences from Other Modes​

• vs. MSD Contactless: MSD emulates magnetic stripe data without chip cryptograms, offering lower security (no liability shift) and no dynamic authentication. qVSDC requires chip interaction, generates ARQC/ARPC cryptograms, and prevents fallback for chip-enabled cards (Service Codes 2xx/6xx prompt contact chip use). It supports advanced CVMs like CDCVM, unlike MSD's limited verification.
• vs. Contact VSDC: Contact VSDC uses physical chip insertion with full EMV sequences (e.g., more APDUs for selection and verification, support for Offline PIN). qVSDC is contactless-only, compresses commands for speed (e.g., fDDA instead of full DDA), lacks Cardholder Selection, and focuses on online processing without offline PIN. It uses Proximity Payment System Environment (PPSE, "2PAY.SYS.DDF01") instead of PSE ("1PAY.SYS.DDF01").
• vs. Full EMV Contactless: qVSDC minimizes commands (e.g., cryptograms generated upfront), skips issuer scripts/authentication in deferred modes, and uses placeholder amounts for early card removal, unlike fuller EMV flows that may require more round trips.

Transaction Flow and Steps​

qVSDC transactions follow a streamlined EMV-like flow, optimized for contactless:

1. Preliminary Processing: Terminal performs risk checks (e.g., amount vs. Reader CVM Required Limit, Floor Limit) and sets TTQ before prompting tap.
2. Discovery/Polling: Reader activates RF field and detects card/device.
3. Application Selection: Builds candidate list via PPSE; selects highest-priority mutual AID (e.g., Visa U.S. Common Debit AID for routing).
4. Initiate Processing: Card requests data (PDOL); terminal sends GET PROCESSING OPTIONS with amount, TTQ, etc.; card generates ARQC and optional fDDA signature.
5. Read Data (Conditional): Fetches records via AFL if needed.
6. Offline Data Authentication (Conditional): Validates via fDDA for offline-capable readers.
7. Cardholder Verification: If required, uses CVM hierarchy (Online PIN > Signature > CDCVM/No CVM); supports pre-tap for devices.
8. Online Processing: Sends ARQC to issuer; receives ARPC for validation.
9. Completion: Generates final cryptogram (TC/AAC) if needed; displays outcome.

For Quick Chip integration, use deferred authorization ('Z3' code) to allow early removal.

Key APDU Exchanges​

qVSDC compresses standard EMV APDUs:

• SELECT PPSE: C-APDU: 00 A4 04 00 0E 32 50 41 59 2E 53 59 53 2E 44 44 46 30 31 00; R-APDU: Returns AID list.
• SELECT AID: C-APDU: e.g., 00 A4 04 00 07 A0 00 00 00 03 10 10 00 (Visa Debit); R-APDU: Includes PDOL.
• GET PROCESSING OPTIONS: C-APDU: 80 A8 00 00 [Lc] 83 [PDOL Data] 00; R-APDU: AIP, AFL, ARQC, fDDA signature.
• READ RECORD: C-APDU: 00 B2 [Record] [P2] 00; R-APDU: Data like PAN (5A), expiry (5F24).
• GENERATE AC: C-APDU: 80 AE [P1] 00 [Lc] [CDOL Data] 00; R-APDU: Cryptogram (9F26), info (9F27), ATC (9F36).

Implementation Requirements​

• Terminals/Readers: EMVCo/Visa-approved; support TTQ, zero Floor Limit (U.S.), disabled Transaction Limit; PCI PTS/PCI DSS compliant; display Contactless Symbol; handle POS Entry Mode '07'.
• Acquirers: Transmit unaltered chip data (Field 55); support deferred authorizations; route based on AID.
• Testing: Level 3 with CDET/ADVT; monitor fallback/declines.
• Merchant/UI: Train on taps; use audio/visual cues; avoid RF interference.

Considerations for Consumer Devices​

Devices (e.g., mobiles) use Form Factor Indicator (FFI) to signal type; primarily support CDCVM (e.g., biometrics). Pre-tap allows CVM before presentment; if not performed, prompt removal and retry. No processing differences from cards in VisaNet.