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EMVCo, FIDO Alliance and W3C have all taken steps to improve online payment security through the development of interoperable technical specifications. In this document we describe the core capabilities provided by some of their specifications, what problems can be solved by combining them, and potential changes to improve how they work together. The technologies in scope for this document are:
This section describes the status of this document at the time of its publication. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at https://www.w3.org/TR/.
This is a draft document for discussion within the Web Payment Security Interest Group.
This is not yet a public document. The expectation is that, once approved by W3C, FIDO, and EMVCo, it will be made public.
This document was published by the Web Payment Security Interest Group as a Group Note using the Note track.
Group Notes are not endorsed by W3C nor its Members.
This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
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This document is governed by the 2 November 2021 W3C Process Document.
This document describes how the technologies in scope may be used together to address a specific use case: secure card payment during an e-commerce guest checkout on the Web (i.e., browser-based scenarios). Our focus is on the guest checkout use case where the user provides information to a merchant, rather than situation where the merchant reuses information previously provided by the user ("card-on-file"). We make no assumptions about the nature of the user's device (mobile phone, laptop, etc.). The goals for this use case are listed below.
There are inherent tensions among some of the goals we list below. We wish to reduce fraud, but not at the expense of user privacy or regulatory requirements. We want to improve the user experience, but not at the expense of security and cost. For editorial reasons, we do not repeat these inherent tensions in the descriptions below.
Please also note that we are explicitly not addressing in this document:
See below for more information on how the technologies in scope can help achieve our goals.
We seek to:
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In this section we summarize the principal capabilities of the technologies in scope. In some cases, the specifications from different organizations may describe similar capabilities, at least at a high level. For example:
The descriptions below are simplified and tailored to the particular guest checkout use case that is the focus of this piece. For more complete descriptions of these technologies, please see corresponding materials from EMVCo, FIDO, and W3C.
When making an online purchase and selecting a card for payment, the cardholder shares their payment data with a merchant. The cardholder may further agree for that merchant to store those payment credentials as a "card-on-file" to facilitate future payments. The cardholder data that is traditionally shared or stored as card-on-file payment data has traditionally included the Primary Account Number (PAN), the card expiry date, cardholder name, alongside the billing address and shipping address. If the PAN and Expiry Date data being stored or processed is exposed to a malicious actor, the stolen account data can be used to perform unauthorized and fraudulent transactions. EMV® Payment Tokenisation defines an ecosystem where surrogate payment data ("Payment Tokens") can be used to replace PANs in a variety of use cases, including card-on-file. Merchants (or their payment service providers) can assume the role of a Token Requestor to request Payment Tokens that will replace PANs being stored in their card-on-file datastore. By substituting Payment Tokens for PANs, Merchants and their payment service providers can remove PAN from their cardholder data environment and may reduce the risk of subsequent fraud should there be an account data compromise event.
Payment Tokens offer security benefits as compared to PANs. The Payment Token not only replaces the PAN but is restricted in its use by the enforcement of related transactional "Token Domain Restriction Controls" (domain restriction controls) during token processing. These domain restriction controls reduce opportunities for unauthorized use or misuse, for example by limiting use of a Payment Token to a specific channel such as e-commerce, for a specific transaction through use of token cryptograms, or to a specific Merchant. Existing security related mechanisms such as use of a card verification numbers can still be used in conjunction with Payment Tokens and domain restriction controls.
Payment Tokens offer additional benefits as well:
EMV® 3-D Secure enables issuing banks to assess an eCommerce payment transaction and authenticate the cardholder if required. The protocol consists of up to two phases:
Merchants that leverage EMV® 3-D Secure for cardholder authentication can benefit from increased security and increased approval rates.
Secure Remote Commerce (SRC) outlines the overall architecture, provides requirements, contains APIs and a Java Script based SDK and user interface guidelines - with an objective to deliver the following benefits:
From a user experience perspective:
FIDO2 refers to the combination of two technologies: Web Authentication and Client-to-Authenticator Protocol (CTAP).
Many smartphones and laptops ship from the factory with FIDO authenticators already built in, making FIDO authentication a natural, low-friction and scalable approach for consumer authentication (e.g., to gain access to a list of cards or to authenticate during a transaction).
FIDO protocols involve two steps: registration and authentication.
The FIDO standards are based on public key cryptography. During FIDO registration, the user creates a PIN code or registers biometric data and the authenticator then generates a public/private key pair specific to the Relying Party. The key pair is not known to any other party. Registration involves sending the public key in a protected way to the Relying Party server.
FIDO Authentication consists of two steps: local user verification followed by on-line authentication. The local user verification step is a prerequisite for the on-line authentication step.
The local user verification step can be either:
For the on-line authentication step, the Relying Party server sends a message to the authenticator which is then cryptographically signed with the private key stored in the authenticator that was used at registration. The signed response is returned to the server where it is verified.
The on-line authentication step thus proves the possession of the FIDO authenticator and constitutes a second factor of authentication while never storing shared secrets or biometric data in the cloud.
Payment Request API defines a browser capability that makes it easier and faster (than Web forms) for merchants to request payment and for users to complete a checkout by returning stored information (e.g., contact information, addresses, and payment credentials). The merchant declares supported payment methods through the API. When the user clicks a "buy button," this causes the browser to determine which payment apps the user has (or could install on the fly) for those payment methods. Payment apps come in three flavors: native mobile apps, Web sites, or the browser itself. If only one payment app matches what the merchant accepts, the browser can launch it automatically. If multiple payment apps match, the browser prompts the user to choose one. The user then interacts with a payment app to complete the transaction. The browser returns data from the payment app to the merchant (or their payment service provider, whoever called the API).
The Payment Handler API defines how Web-based payment apps register the payment methods they support with the browser, how the browser launches the payment app, and how the payment app returns data upon completion of user interaction. How a payment app stores information, authenticates the user, and communicates with payment services (e.g., token service providers, issuing banks, etc.) lies outside the scope of the Payment Handler API.
Secure Payment Confirmation is a Web API to support streamlined authentication during a payment transaction. In essence, SPC enhances Web Authentication for payments. It does so through three important capabilities:
Note: For practical reasons Secure Payment Confirmation was initially specified as a payment method. Thus, in its initial form, SPC is closely tied to Payment Request API.
The tables below summarize how the technologies in scope can help achieve the goals.
Goals | How Technologies and standards help |
---|---|
Alleviate the burdens associated with passwords |
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Reduce the friction of user authentication processes to access the list of cards |
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Reduce the friction of user authentication process to authenticate for the transaction |
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Reduce typing and other friction associated with providing addresses, contact information, and payment credentials as part of completing checkout |
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Reduce confusion that can result from redirecting the user away from a merchant site to a payment site |
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Reduce confusion that can arise from very different checkout experiences across the Web |
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Improve lifecycle management of credentials |
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Goals | How Technologies and standards help |
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Prevent account takeover and security attacks |
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Reduce account data compromise and PCI SSC non-compliance |
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Ensure that only an authorized party can use a card |
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Improve the ability of account issuers to assess transaction risk |
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Goals | How Technologies and standards help |
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Lower front-end integration costs |
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Remove or reduce the scope of PCI SSC compliance |
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Goals | How Technologies and standards help |
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Protect biometric data |
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Prevent tracking users across sites |
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Goals | How Technologies and standards help |
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Make it easier to meet strong customer authentication regulatory requirements |
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Make it easier to meet privacy regulatory requirements |
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Below we describe some of the ways that the technologies in scope relate, especially through the lens of 3-D Secure authentication. The technologies in scope may also be used in other authentication scenarios (e.g., SPC with Secure Remote Commerce) but we do not discuss those relationships here in detail. In the previous version of this document we discussed other relationships among the technologies (e.g., Payment Request API used to implement a Secure Remote Commerce flow), but since then we have turned our focus to authentication flows.
In a 3-D Secure flow:
In this flow, FIDO and Secure Payment Confirmation may be used for cardholder authentication initiated either by the issuer or by the merchant (or its service provider).
Authentication Method | Relying Party (RP) | 3DS Flow | Initiated by | Validated by | Note | |
---|---|---|---|---|---|---|
IE-1 | SPC or FIDO | Issuer | Challenge | Issuer | Issuer | Issuer environment; for SPC see 3DS 2.3 |
In more detail:
Authentication Method | Relying Party (RP) | 3DS Flow | Initiated by | Validated by | Note | |
---|---|---|---|---|---|---|
ME-1 | FIDO | Merchant/PSP | Frictionless | Merchant/PSP | Merchant/PSP | Delegated authentication. See FIDO Authentication and EMV 3-D Secure – Using FIDO for Payment Authentication |
ME-2 | SPC | Merchant/PSP | Frictionless (though Issuer may challenge) | Merchant/PSP | Merchant/PSP | Delegated authentication, e.g., RP is PSP for reuse across merchants |
ME-3 | SPC | Issuer | Challenge | Merchant/PSP | Issuer | Merchant environment; see 3DS 2.3 |
In more detail:
This section identifies some payment experience improvements for consideration in current or future specifications (or their implementations).
get()
from a cross-origin
iframe but does not allow create()
. SPC diverges here from
Web Authentication, and there are ongoing conversations within W3C
about whether Web Authentication should support cross-origin credential
creation (and thus SPC could be simplified). We also note that 3-D
Secure currently limits the use of cross-origin iframes to the
challenge flow (and not, for example, registration).
From a Payment Request perspective, if the merchant accepts PAN-based card payments, then the Payment Request API is in scope for PCI DSS. W3C and PCI SSC are in conversation to understand any potential impact of Payment Request API on PCI DSS compliance. For relevant PCI DSS good practice (e.g., if using Payment Request API from within an iframe), see PCI SSC FAQ 1292.
For information about Payment Tokenisation and PCI DSS, see How does PCI DSS apply to EMVCo Payment Tokens?.
EMVCo is working closely with PCI SSC to maintain the Security Evaluation for 3-D Secure solutions, via the PCI 3DS defined and operational process.
EMV® 3-D Secure supports all EU SCA factors, including inherence, through a range of authentication methods, such as the facilitation of biometrics (e.g., biological and behavioral). These factors can be delivered in or out-of-band, or using FIDO Authentication Standards. EMV 3-D Secure v2.2 (and following versions) was specifically designed to support an improved user experience for biometrics.
An EBA Opinion published on 16 October 2019 references the RTS and states (at point 15) that the "[EMV] 3DS v2.2. communication protocol… should enable the application of the full range of SCA exemptions specified in the RTS and the out-of-scope of SCA transactions, such as payee-initiated transactions." For more information, see EMV® 3-D Secure and the PSD2 Requirements for Strong Customer Authentication.
See the FIDO Alliance's Meet PSD2 Requirements with FIDO and (jointly developed with EMVCo) Technical Note: FIDO Authentication and EMV 3-D Secure – Using FIDO for Payment Authentication.
Secure Payment Confirmation adds dynamic linking capabilities to FIDO / Web Authentication. See also notes on Using SPC to fulfill PSD2 Requirements for SCA and Dynamic Linking.
See the FIDO white paper FIDO Authentication and the General Data Protection Regulation.
FIDO is used for authentication. OAuth 2 enables the delegation of authentication to other parties.
In more detail:
For more information, see the FIDO white paper Enterprise Adoption Best Practices – Integrating FIDO & Federation Protocols.
Referenced in: