An email code shows that someone can access an inbox. A text message shows that they have access to a particular phone.
But sometimes you need to answer a different question before accepting a signature: is the person signing the document the same person shown on their ID?
That's where Signater's facial biometrics come in.
During signing, the signer submits a photo ID and takes a selfie with a liveness check. Signater analyzes the live face and compares it with the portrait on the identity document. The signature can only proceed when the comparison meets the required threshold.
How does facial biometric verification work?
Signater's facial biometric verification combines three steps:
- Identity document: the signer submits a photo ID such as a driver's license or passport.
- Selfie with liveness detection: Signater checks that a real person is present in front of the camera during the verification.
- Face matching: Signater compares the live face with the photo on the identity document.
Because face matching needs both images, enabling facial biometrics also enables the identity document and advanced selfie checks.
1. The signer submits an identity document
The first step captures the front of a photo ID. Depending on the document and verification flow, Signater may also request the back.
Signater checks that the submitted image is an identity document with a photograph. An image that doesn't meet the requirements can be rejected before it reaches the face-matching step.
The document remains associated with the envelope as evidence of the verification. It is not embedded in the signed PDF that the parties download and share.
2. The selfie includes liveness detection
A regular selfie is simply a photograph. An advanced selfie with liveness detection adds a verification step designed to determine whether a live person is in front of the camera at the time of capture.
This helps detect presentation attacks such as attempting to use a printed photograph, another screen or a recorded image instead of presenting the person directly to the camera.
During the capture, the signer follows the instructions shown on screen. The liveness check uses presentation attack detection tested against the ISO/IEC 30107-3 standard.
The analysis is performed on Signater's servers. The browser or mobile device captures the required images and sends them for verification.
3. Signater performs face matching
After the images are captured, Signater compares the face in the live selfie with the portrait on the identity document and calculates a similarity score.
The comparison produces a score from 0 to 100. The signature can proceed only when the result reaches the minimum threshold configured for the verification.
If the comparison doesn't meet the threshold, the signer is told that the verification failed and can try again. If the maximum number of attempts is reached, the envelope may be cancelled and the signer may need to request a new signing link from the sender.
The three steps work together: possession of someone else's ID is not enough. The person completing the verification also has to present a face that matches the portrait on the submitted document.
Does the signer need to install an app?
No.
The signer opens the envelope in a browser on a phone or computer, and the device's camera is used to capture the required images.
If the signer is using a computer without a camera, Signater can transfer the capture step to their phone using a QR code. Once the verification is complete, they return to the computer and continue signing.
What does the certificate record?
The certificate of completion records the identity verification factors used during the signing process, including:
- Identity document submitted by the signer
- Advanced selfie with verified liveness detection
- Facial biometrics / face matching
The selfie may also be included in the certificate of completion. The identity document itself remains stored as verification evidence associated with the envelope rather than being embedded in the signed PDF.
This gives the signing record a clear history of which identity verification steps were performed.
Biometric information can be subject to additional privacy requirements depending on the applicable law. Signater's Privacy Policy explains how identity verification data is handled.
How to enable facial biometrics
Facial biometrics are configured for individual signers when you create an envelope:
- Open the Signers step in the envelope editor.
- Select the signer who should complete the verification.
- Under Advanced identity validation, enable Facial biometrics.
- Save the signer and continue configuring the envelope.
Signater automatically adds the identity document and advanced selfie requirements because both are needed for the face-matching step.
You can also combine facial biometrics with additional verification factors, such as an SMS code.
When should you use facial biometrics?
Not every contract needs the same level of identity verification.
Facial biometrics make the most sense when you need stronger evidence that the person signing is the person identified in the submitted document.
- Guarantees and co-signers: when you want additional assurance that the signer is the person identified in the agreement.
- Loans and financing: when an identity-related fraud risk could have significant financial consequences.
- Real estate transactions and powers of attorney: when the document involves significant assets or grants authority to another person.
- Customer onboarding and account opening: when confirming the customer's identity is an important part of the process.
For routine agreements where the parties already know each other, a lighter verification method such as an email or SMS code may provide a better balance between assurance and signing friction.
Facial biometrics vs. other identity checks
Different verification methods answer different questions:
- Email verification: does the signer have access to the email address?
- SMS verification: does the signer have access to the phone number?
- Identity document verification: what identity is represented by the submitted document?
- Facial biometrics: does the live face presented during verification match the portrait on that identity document?
You can combine these factors when the signing workflow calls for additional evidence.
Availability
Identity document verification, advanced selfie and facial biometrics are available on the Business and Enterprise plans. The basic selfie is available on every Signater plan, including Free.
See all of the identity validation options available in Signater.
Want to try the platform? Create a free account and send up to three envelopes per month on the Free plan, with no credit card required.
