Authentication

Authentication products assess different factors to confirm the identity of existing clients (whose identity was previously verified) when they access your services.

You can use single authentication products to perform specific checks, or combine them into Authentication Solutions for different levels of authentication or step-up flows.

We offer the following:

Biometric Authentication

Fourthline checks if the client's selfie photo and video are authentic, and compares them to those from their latest successful Identity Verification case to confirm it’s the same person.

We perform the following checks:

Check	Description	Required
Self-capture	We confirm that the selfie and liveness video were captured live by the client on their device, not inserted or uploaded. Only one face may appear.
Image quality	We verify image quality to ensure processing accuracy.
Authenticity	We check that: • The selfie is authentic (not a screen or printed photo). • The video shows a live, moving client without physical or digital masking.
Face match	We compare the selfie to the original ID verification image. Scores ≥ 90% are auto-approved; < 60% triggers human review.

We request a new selfie if:

• The photo doesn’t show the client’s face clearly.
• It’s an image of another photo or screen.
• The angle prevents matching with the ID photo.
• Quality issues prevent verification (e.g., poor lighting, sunglasses, eyes closed).

Document Authentication

When an existing client receives a new identity document, Fourthline verifies it is visible, valid, authentic, supported, and in good condition.
We then compare its data to the document in the client’s latest successful Identity Verification case.

We perform the following checks:

Check	Description	Required
Self-capture	Confirms the document was captured live by the client, not uploaded or inserted.
Personal data	Validates and compares all personal details with the last verified document. Mismatches trigger verification or client confirmation.
Document validity	Checks if the document is valid, supported, and undamaged.
Security features	Detects and verifies visible security features. Missing data triggers human review.
Authenticity	Ensures document photos and videos are authentic and not screen captures.
ID video	A 10-second video confirms the document’s authenticity. Human review flags deepfakes.
Chip data	If NFC data is available, we compare it with MRZ and VIZ data for consistency.

Upload reference data

When you integrate Document Authentication via API, use one of the following:

1. Completed Identity Verification — Create the workflow for a client who already has a successful Identity Verification with Fourthline. Fourthline uses the existing client data; you do not need to upload reference data.
2. Partner-uploaded reference data — If the client does not have a completed Fourthline Identity Verification on file, upload previous client data before the new identity document.

For option 2:

• Call Upload/Update client data with identityData.type set to ReferenceDocumentData and the reference personal data fields.
• Use the Document Authentication (reference data) request example in the API reference.

{
  "identityData": {
    "type": "ReferenceDocumentData",
    "firstName": "John",
    "lastName": "Smith",
    "nationality": "NLD",
    "placeOfBirth": "SPECIMEN",
    "birthDate": "1985-04-04"
  }
}

For a full list of supported identity documents, contact your Fourthline delivery manager.

Location Authentication

Fourthline checks whether the client’s device geolocation and metadata are valid and uncompromised, comparing them with prior Identity Verification data.

We perform the following checks:

Check	Description	Required
Self-capture	Confirms geolocation data is device-originated and client-authorized.
Geolocation	Validates accuracy, presence, and non-prohibited location.
IP address	Verifies IP authenticity and region consistency.
Metadata	Compares device language, region, and SIM data with IP/geolocation to ensure alignment.
Fraud hot spot	Flags known high-risk locations linked to financial crime.
Address	Validates the residential address is complete, supported, and non-industrial.

For the full list of supported countries and territories, contact your Fourthline delivery manager. The list of prohibited countries may change due to evolving European sanctions.

NFC Authentication

Fourthline checks whether the NFC chip embedded in a supported document is authentic and extracts personal data for comparison with previously verified data.
We unlock the chip using either Document Photo/Liveness or the Card Access Number (CAN) provided by the client.

Check	Description	Required
Chip data	Compares NFC chip data with MRZ and VIZ information, prioritizing chip accuracy.
Chip portrait	Confirms the color portrait on the chip matches the monochrome portrait on the document.

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