Author: Xuanzhe Jia

  • Newcomers | Designing a Future-Proof Combination of SCA Elements under PSD2 and PSR

    Article Structure

    1. The Basic Principles and Its Implementations
      1. From Different categories
      2. Independence between Each Other
      3. Reuse of Elements
    2. The Evolvement from PSR
      1. Comprehensive Scenario Coverage
      2. Accessibility for Everyone
      3. Elements from Same Category
      4. Awaiting New RTS
    3. A Future-Proofed Solution
      1. More Than Two Elements from More Than One Category for Each Scenario
      2. Reuse as Much as Possible
      3. Give Autonomy Back to Users

    Bearing in mind those 3 different types of elements individually for SCA (Strong Customer Authentication), the task for the compliance and product teams is to combine elements to comply with the regulatory requirements for security enhance and fraud reduction, under both the current PSD2 (the Revised Payment Services Directive) and the foreseeing PSR (the Payment Services Regulation). Here, we are going to elaborate and experiment on designing a future-proofed compliant SCA solution.

    1. The Basic Principles and Its Implementations

    a. From Different Categories

    This is direct, just take two elements, each from a different category (possession, knowledge, inherence). For example, for log-in, a PSP (payment services provider) may choose facial recognition (inherence) and password (knowledge) to combine. Similarly, for digital signature, as advised by EBA (European Banking Authority), if PSP needs to use a key stored in the user’s device which can only be accessed by entering the correct PIN or other forms of knowledge, then this digital signature also meets the requirement on different categories.

    Notwithstanding, our imagination shall not be caged. It says from different categories but never says only 2 elements from different categories. We may have 3 or 4 elements from two or three categories as well (it’s not nonsense!).

    b. Independence between Each Other

    The elements used for SCA should be independent from each other. Independence applies both logically and technically. Article 9 of the PSD2 SCA RTS requires that the use of the elements ‘is subject to measures which ensure that, in terms of technology, algorithms and parameters, the breach of one of the elements does not compromise the reliability of the other elements’.

    Logical independence could be easily understood. For example, if a person’s log-in password is stolen, but the log-in also requires facial recognition, then without the presence of this person, the log-in cannot happen.

    Technical independence may need the support from IT team. It may require the adoption of trusted execution environments, the deployment of separate TOTP (Time-based One-Time Password) app protected cryptographically, multiple communication channels etc.

    c. Reuse of Elements

    In the same session of the authentication during log-in, for payment initiation, it’s considered acceptable to adopt only another one element to verify. It should be noted that this reuse of element still needs to follow “independence” and “different categories”. And for the new element which is to be carried out during the payment initiation, it shall enable the fulfilment of dynamic linking (dynamic linking and authentication code will be introduced in another piece). The reuse can provide the PSUs (Payment Service Users) with better user experience and simplify the design of SCA mechanism.

    2. The Evolvement from PSR

    As the upgrade in payment service regulation is coming, the SCA updates from PSD2 are spread out from Articles 85 to Article 89 in PSR. Here we touch on 4 observations.

    a. Comprehensive Scenario Coverage

    In PSR, besides 3 well-defined scenarios for SCA implementation, a risk-based approach is also taken to broaden the coverage. It requires PSPs to screen the customer journey, combined with industry knowledge and enterprise know-hows, to delineate potential fraud risk points and determine the necessity of SCA.

    A payment service provider shall apply strong customer authentication where the payer:

    (a)accesses its payment account online;

    (b)accesses payment account information;

    (c)places a payment order for an electronic payment transaction;

    (d)carries out any action through a remote channel which may imply a risk of payment fraud or other abuses.

    b. Accessibility for Everyone

    From the point of view of product design, the effective Directive (EU) 2019/882 has been pushing consumer banking services to include accessibility requirements. The accessibility requirement is being advanced specifically to SCA application under the Article 88 of PSR with wider financial services scope.

    To improve accessibility, the PSR requires PSPs to offer diverse authentication methods to allow everyone including people with conditions to use the offered financial services with equal chance under protection from fraud with compliant SCA. This includes persons with disabilities, older individuals, users with low digital literacy, and those without access to digital tools. It requires diversified solutions to be inclusive for different people compared to only single choice to authenticate. For example, for a desktop browser user, PSP shall not assume the user can authenticate with smart phone.

    At this moment, the potential available options include but not limited to voice recognition, card-reader authentication, hardware tokens, desktop sync options, or assisted setup flows, etc.

    Under PSD2, for compliance purpose, PSPs may choose to refuse to proceed for PSUs who fail to execute the designed SCA properly. In the future, under the proposed PSR, the accessibility is not only making the fraud protection from SCA accessible, but also the financial service per se.

    c. Elements from Same Category

    Contrary to the PSD2, PSR stipulates clearly that the elements for SCA do not necessarily belong to different categories. PSR preserves the requirement on full independence between each element. They realize that to preserve independence, from different categories is not a necessary condition. This reflects a regulatory shift, placing more responsibility on the market to ensure effective security and let the market player create above bottom line.

    For those big players with better product and IT, they may explore same category solutions. For small players, to secure the independence level, they may remain using elements from different categories to achieve the regulatory requirement and keep the fraud countermeasure effective.

    For accessibility, allowing SCA elements from same categories is necessary as well because certain elements are not highly accessible for all the people.

    d. Awaiting New RTS

    We shall foresee the coming of RTS to give detailed guidance after the PSR comes into effect. According to Article 89 of PSR, it’s believed that the state of art and the expressed voices from PSPs and PSPs are factors to decide how far the RTS shall be stretched realistically.

    When developing the draft regulatory technical standards referred to in paragraph 1, the EBA shall take into account:

    (a)the need to ensure an appropriate level of security for payment service users and payment service providers, through the adoption of effective and risk-based requirements;

    (b)the need to ensure the safety of payment service users’ funds and personal data;

    (c)the need to secure and maintain fair competition among all payment service providers;

    (d)the need to ensure technology and business-model neutrality;

    (e)the need to allow for the development of user-friendly, accessible and innovative means of payment.

    3. A Future-Proofed Solution

    No matter at which stage of SCA development, to create or refine, a PSP stands, a future-proofed solution could consider the following 3 points.

    a. More Than Two Elements from More Than One Category for Each Scenario

    Ideally, a matrix of SCA capabilities is to be established. It may define each element with identifying its category, independence compatibility, support for dynamic linking, accessibility level, and resistance to fraud.

    After creating this matrix, taking desktop and mobile into account, based on the risk points analysis on the customer journey, for each scenario requiring SCA, more than 2 elements from more than 1 category including at least 1 highly accessible element shall be offered. It helps to comply with the current legislation but also easily adapt to the foreseen changes.

    b. Reuse as Much as Possible

    Reuse of elements has been explained above. I believe it will serve as a steering pivot in the new SCA era. The ultimate compliant goal is to reduce fraud for users. However, in essence, financial services are products for users to use. An amazing product shall be a compliant product. But a merely compliant product can sink without a trace in the market. Considering more scenarios to be designated as SCA-necessary, except choosing what elements are available to offer, to reuse element as much as possible in sessions will increase the user experience and, furthermore, lower the design difficulty of accessibility options.

    c. Give Autonomy Back to Users

    For the set-up of SCA, PSPs may give the autonomy back to PSUs deciding how to combine elements for different scenarios. Since educating customers about fraud is also mentioned as an obligation of PSP in PSR, and there are the aforementioned accessibility requirements, by guiding PSUs to customize their own compliant SCA solutions, it can achieve PSP for multiple regulatory purposes and make it a feature of your product.

     

    This article consolidates existing regulations and forward-looking trends to offer a strategic view of combining SCA elements. As we prepare for a new era under the PSR, flexibility, user empowerment, and risk-based thinking can be central to SCA success. Please don’t hesitate to reach out for any discussion over this and any related topics.

    In writing this piece, I found the following references useful:

    PSD2

    PSD2 SCA RTS

    PSR

    EBA Opinion on SCA

    Ideem: How PSD3 Could Reshape the Future of Digital Identity

    OneSpan: Prepare for PSD3

    VIXIO: PSD3 Pending

  • Newcomers|Understanding the Three SCA Elements

    #PSD2 #PSD3 #PSR #EBA #SCA #Knowledge #Possesion #Inherence #PaymentsCompliance #FintechRegulation

    In the EU, to enhance payment security and reduce fraud, multi-factor authentication (MFA) under the Strong Customer Authentication (SCA) requirements of the Second Payment Services Directive (PSD2) is enforced. It requires payment service providers (PSPs) to implement the authentication mechanism for payment service users (PSUs) combining at least two out of three elements from the following categories:

    • Knowledge
    • Possession
    • Inherence

    To better understand these categories, I found the European Banking Authority’s (EBA) Opinion and Q&As particularly helpful, and I quote or paraphrase their explanations here.

    What Does SCA Look Like in Real Life?

    The term might look unfamiliar. Let’s take ING’s mobile banking app as an example. The app first requires binding to the user’s mobile phone (possession). At login, the user must provide either a password (knowledge) or use facial recognition (inherence). When initiating a transaction, the app again relies on the device (possession) and requires a separate transaction PIN (knowledge), distinct from the login password.

    A Closer Look at the Three SCA Elements

    Knowledge – Something only the user knows

    To qualify as knowledge, the information should be secretive to PSU, which means it is not easily known by third party. PSPs are further required to have mitigation measures (e.g., the communication sessions are protected against the capture of authentication data) in place in order to prevent the disclosure to unauthorised parties.

    The following elements could constitute a knowledge element: a password, a PIN, knowledge-based responses to challenges or questions, a passphrase and a memorised swiping.

    Possession – Something only the user has

    Possession includes both physical possession and something that is not physical (e.g, an app).

    • For a device (physical possession) to be used as a possession element, generation or receipt of a dynamic validation element on the device as a proof shall be enabled. For example,one-time password (OTP) received via text message or generated via software installed.
    • For mobile apps, similarly, web browsers or the exchange of (public and private) keys, to be used as a possession, it shall contain a device binding process that ensures a unique connection between the PSU’s app, web browsers, or the exchange of (public and private) keys, and device.

    Inherence – Something the user is

    Inherence includes biological and behavioural biometric of the user. It relates to physical properties of body parts, physiological characteristics and behavioural processes created by the body, and any combination of these. For example, inherence may include retina and iris scanning, fingerprint scanning, face and hand geometry (identifying the shape of the user’s face/hand), the angle at which the PSU holds the device.

    Are These Categories Changing under PSD3 and PSR?

    Although the proposed PSD3 and the new Payment Services Regulation (PSR) bring structural and supervisory changes, the definitions of knowledge, possession, and inherence under SCA remain unchanged. This means compliance professionals can continue to rely on the current regulatory interpretations considering these 3 categories of elements.

    More Real-World Examples

    The following three tables released and validated by EBA are quite useful to verify if the considered thing or method can be classified into one of categories:

    Table 1 — Non-exhaustive list of possible inherence elements

    Element

    Compliant with SCA?

    Fingerprint scanning

    Yes

    Voice recognition

    Yes

    Vein recognition

    Yes

    Hand and face geometry 

    Yes

    Retina and iris scanning

    Yes

    Keystroke dynamics  

    Yes

    Heart rate or other body movement pattern identifying that the PSU is the PSU (e.g. for wearable devices)  

    Yes

    The angle at which the device is held

    Yes

    Information transmitted using a communication protocol, such as EMV® 3-D Secure

    No

    Memorised swiping path

    No

    Table 2 — Non-exhaustive list of possible possession elements

    Element

    Compliant with SCA?

    Possession of a device evidenced by an OTP generated by, or received on, a device (hardware or software token generator, SMS OTP)

    Yes

    Possession of a device evidenced by a signature generated by a device (hardware or software token) 

    Yes

    Card or device evidenced through a QR code (or photo TAN) scanned from an external device

    Yes

    App or browser with possession evidenced by device binding — such as through a security chip embedded into a device or private key linking an app to a device, or the registration of the web browser linking a browser to a device 

    Yes

    Card evidenced by a card reader 

    Yes

    Card with possession evidenced by a dynamic card security code

    Yes

    App installed on the device

    No

    Card with possession evidenced by card details (printed on the card)

    No

    Card with possession evidenced by a printed element (such as an OTP list)

    No

    Table 3 — Non-exhaustive list of possible knowledge elements

    Element

    Compliant with SCA?

    Password  

    Yes

    PIN

    Yes

    Knowledge-based challenge questions

    Yes

    Passphras

    Yes

    Memorised swiping path

    Yes

    Email address or user name

    No

    Card details (printed on the card)

    No

    OTP generated by, or received on, a device (hardware or software token generator, SMS OTP)

    No

    Printed matrix card or OTP list

    No

    Main Resources

    PSD2
    Regulatory technical standards for strong customer authentication and common and secure open standards of communication
    EBA Opinion on the elements of strong customer authentication under PSD2
    EBA Q&A
    PSD3
    PSR