Face Comparison
Face Comparison can be requested along with other checks (i.e. Document authenticity, Face match etc.) or as a standalone check.
The Identity Verification (IDV) service also provides a face comparison check that can be used to authenticate a user by using their selfie. This check does an AI comparison between a live user selfie and the reference facial image to return a confidence score. Combined with a liveness check, this can be used for selfie authentication.
Configure selfie auth
Before triggering the selfie auth check, you have to create an IDV session configured with Face comparison and Liveness check. Additionally, a reference face image has to be uploaded against which the live selfie will be compared.
Session specification
To use this service, you have to create session specification with at least two checks - Liveness and Face Comparison. You can also set the maximum retries for liveness and manual check option for face comparison checks. Currently, only an automated face comparison is available.
const { SessionSpecificationBuilder, RequestedLivenessCheckBuilder, RequestedFaceComparisonCheckBuilder, SdkConfigBuilder} = require('yoti');// Liveness check with 3 retriesconst livenessCheck = new RequestedLivenessCheckBuilder() .forStaticLiveness() .withMaxRetries(3) .build();// Face Comparison check with manual check set to neverconst faceComparisonCheck = new RequestedFaceComparisonCheckBuilder() .withManualCheckNever() .build();// Configuration for the client SDK (Frontend)const sdkConfig = new SdkConfigBuilder() .withSuccessUrl('/success') .withErrorUrl('/error') .withAllowHandoff(true) .build();// Buiding the Session with defined specification from aboveconst sessionSpec = new SessionSpecificationBuilder() .withClientSessionTokenTtl(600) .withResourcesTtl(90000) .withUserTrackingId('some-user-tracking-id') .withRequestedCheck(livenessCheck) .withRequestedCheck(faceComparisonCheck) .withSdkConfig(sdkConfig) .build();Initialise the Yoti client
The included DocScan/IDV Client includes several helper methods to interact with the Yoti's API. You can initialise the client using your unique SDK ID and PEM file.
const path = require('path');const fs = require('fs');const { IDVClient } = require('yoti');const YOTI_CLIENT_SDK_ID = 'YOTI_CLIENT_SDK_ID';const YOTI_PEM = fs.readFileSync(path.join(__dirname, '/path/to/pem'));const idvClient = new IDVClient(YOTI_CLIENT_SDK_ID, YOTI_PEM);Create a session
You can use the createSession method from the above client to create a Yoti session. Session specification needs to be passed as an argument. After the session is successfully created, you will get a Session ID that can be used to retrieve the Session configuration.
let sessionId, sessionToken;idvClient .createSession(sessionSpec) .then((session) => { sessionId = session.getSessionId(); sessionToken = session.getClientSessionToken(); }) .catch((err) => { console.log(err) });const sessionConfig = await idvClient.getSessionConfiguration(sessionId);Create a Face Capture resource
Before uploading the reference face image, you have to create a Face capture resource. To do this, a Requirement ID from the Face Capture requirements needs to retrieved. This can then be used to create a face capture resource. If successful, you will receive a Resource Id.
const { CreateFaceCaptureResourcePayloadBuilder, UploadFaceCaptureImagePayloadBuilder,} = require('yoti');const resourceRequirements = sessionConfiguration.getCapture().getFaceCaptureResourceRequirements()[0];const requirementId = resourceRequirements.getId();const faceCapturePayload = new CreateFaceCaptureResourcePayloadBuilder() .withRequirementId(requirementId) .build();const faceCaptureResource = await idvClient.createFaceCaptureResource(sessionId, faceCapturePayload);const resourceId = faceCaptureResource.getId();Upload a reference image
To do accurate face comparison, a reference facial image of the user is required. You have to get the contents of this image which can then be uploaded using the Doc Scan Client. You also have to pass in the Resource Id retrieved earlier
const fs = require('fs');const imageBuffer = fs.readFileSync('path-to-selfie-jpeg');const faceCaptureImagePayload = new UploadFaceCaptureImagePayloadBuilder() .forJpegImage() .withImageContents(imageBuffer) .build();await idvClient.uploadFaceCaptureImage(sessionId, resourceId, faceCaptureImagePayload);Client-side view
The next step is to load the Yoti client-side SDK. To do this, you need the below parameters generated with the session creation request above:
- Session ID
- Session Token
We then utilise these to construct a Web URL which loads the Yoti Client SDK. The URL is in the following format:
https://api.yoti.com/idverify/v1/web/index.html?sessionID=<sessionID>&sessionToken=<sessionToken>Once the above URL launches in a web browser, it will take the user through the Selfie and liveness capture flow. For more detailed steps, please refer to the Client side user view page.
Retrieve results
Once a session has been completed, the associated checks' results and resources can be retrieved using the session ID. Each check would contain a recommendation and a breakdown. The resources however are not directly included in the results, but contain a media ID. This can be used to fetch the actual media resource.
The liveness part of the process may contain multiple checks, as a liveness check is generated for each allowed retry. For a face comparison to be considered a 'PASS' overall, the recommended action is to confirm that at least one Liveness check is 'Approve' and the Face Comparison check is 'Approve'.
Retrieve checks
idvClient.getSession(sessionId).then(sessionResult => { const state = sessionResult.getState(); const livenessChecks = sessionResult.getLivenessChecks(); livenessChecks.map(check => { const id = check.getId(); const state = check.getState(); const resourcesUsed = check.getResourcesUsed(); const report = check.getReport(); const recommendation = report.getRecommendation().getValue(); const breakdown = report.getBreakdown(); breakdown.forEach(function(breakdown) { const subCheck = breakdown.getSubCheck(); const subCheckResult = breakdown.getResult(); }); }) const faceComparisonChecks = sessionResult.getFaceComparisonChecks(); faceComparisonChecks.map(check => { const id = check.getId(); const state = check.getState(); const resourcesUsed = check.getResourcesUsed(); const report = check.getReport(); const recommendation = report.getRecommendation().getValue(); const breakdown = report.getBreakdown(); breakdown.forEach(function(breakdown) { const subCheck = breakdown.getSubCheck(); const subCheckResult = breakdown.getResult(); }); })}).catch(error => { console.log(error); // handle error})Retrieve resources
idvClient.getSession(sessionId).then(sessionResult => { const resources = sessionResult.getResources(); const faceCaptureResources = resources.getFaceCaptureResources(); const staticLivenessResources = resources.getStaticLivenessResources(); staticLivenessResources.map(resource => { const id = resource.getId();m const type = resource.getLivenessType(); const mediaId = check.getImage().getId(); })}).catch(error => { console.log(error); // handle error})Retrieve media
idvClient.getMediaContent(sessionId, mediaId).then(media => { const buffer = media.getContent(); const mimeType = media.getMimeType(); const base64Content = media.getBase64Content(); // handle base64content or buffer}).catch(error => { console.log(error) // handle error})