What is Strong Customer Authentication (SCA) under PSD2?

Strong Customer Authentication (SCA) is a security requirement introduced by PSD2 (Revised Payment Services Directive) to
enhance the security of online payments and reduce fraud. SCA
mandates that financial institutions and payment service
providers implement multi-factor authentication (MFA) for electronic transactions, ensuring that only legitimate users can access accounts and approve
payments.

To comply with SCA, authentication must involve at least two of the following three
factors:

1. Knowledge – Something the user knows (e.g., a password or PIN).
2. Possession – Something the user has (e.g., a smartphone, hardware token, or
   smart card).
3. Inherence – Something the user is (e.g., biometrics like fingerprints or facial
   recognition).

SCA applies to most electronic payments within the European Economic Area (EEA). For
example:

• A customer logging into an online banking account may need to
  provide both a password (knowledge) and confirm the login via a mobile push
  notification (possession).
• A user making an online payment may be required to authenticate
  using biometrics (inherence) and approve the payment
  through their banking app (possession).

Certain transactions may be exempt from SCA, such as:

• Low-value transactions (below €30).
• Recurring payments (e.g., subscriptions).
• Transactions deemed low-risk based on fraud analysis.

Traditional authentication methods like passwords and SMS OTPs are still widely used but
are vulnerable to phishing attacks. Passkeys, based on WebAuthn and
FIDO2, offer a phishing-resistant alternative by leveraging
cryptographic authentication and device-bound credentials. Banks and fintech companies
implementing passkeys can meet SCA requirements while improving both security and user
experience.

Passkeys enable strong authentication PSD2 compliance by leveraging cryptographic key pairs and device-bound credentials for seamless, phishing-resistant logins.

By enforcing Strong Customer Authentication (SCA), PSD2 enhances transaction
security, reducing fraud risks and increasing trust in digital banking and online
payments.