Device fingerprinting is the association of client browser attributes with a specific transaction. This fits into the 3DS flow prior to a 3DS Authentications call. Device fingerprinting can be used within the PCI or PCI w/ CVV mode of the TokenEx iFrame or built into your own checkout workflow.

When device fingerprinting is used, the authentication request will also include information about the cardholder’s browser. Although this may seem like duplicative work, the device fingerprint is obtained via a script provided by the ACS, while the browser data in the authentication request comes from the merchant. The ACS then looks for a match by comparing the device fingerprint with the browser data from the authentication request. Since the browser information is retrieved through remote JavaScript calls, it is recommended to gather the required browser data for the authentication request simultaneously with the device fingerprinting.

TokenEx iFrame

The iFrame configuration object has three optional fields:

The API key used to generate the authenticationKey must have the 3DS permission enabled. Contact Support to enable this permission.

When the PAN is tokenized, a SupportedVersions call is processed in the background. That SupportedVersions response is included in the Tokenize response as ThreeDSecureResponse. If the ThreeDSecureResponse has a threeDSMethodUrl, device fingerprinting can be performed and the browser attributes are associated with the ThreeDSecureResponse's threeDSServerTransID. If device fingerprinting can be performed, a hidden iframe is added to the same container housing the existing PAN iframe. The hidden iframe loads a script which associates the browser attributes with the threeDSServerTransID and then sends a base64 encoded notification to the threeDSMethodNotificationUrl.

The threeDSServerTransID should then be used within the ThreeDSecure/Authentications request in the ServerTransactionId field and the ACS will take the browser attributes into account when determining whether to issue a challenge.

Success Example

A successful device fingerprinting will generate an iFrame Notice event, the tokenize response will have a threeDSecureResponse containing a threeDSMethodUrl, and a notification will be sent to the threeDSMethodNotificationUrl. Upon receipt of the notification, include MethodCompletionIndicator as 1 (successful) in the Authentications request.
If a notification is not received within 10 seconds of the TokenEx iFrame notice indicating device fingerprinting success, an unknown issue has occurred in the client's browser and the MethodCompletionIndicator should be included as 2 (not successful) in the Authentications request,

{"type":"3DS Device Fingerprinting","success":true}

{ 
    "firstSix": "123456", 
    "lastFour": "1234", 
    "forterInitResponse": null, 
    "kHash": "", 
    "threeDSecureResponse": [ 
        { 
            "threeDSMethodURL": "https://example.com/browser_attributes", 
            "acsStartProtocolVersion": "2.1.0", 
            "acsEndProtocolVersion": "2.1.0", 
            "threeDSServerStartVersion": "v1", 
            "threeDSServerEndVersion": "v1", 
            "directoryServerID": "M000000004", 
            "dsStartProtocolVersion": "2.1.0", 
            "dsEndProtocolVersion": "2.2.0", 
            "dsIdentifier": "SANDBOX_DS", 
            "threeDSServerTransID": "de119ede-cbe8-4117-835a-c6ec33ea602b" 
        } 
    ], 
    "token": "96d3b89g-16ab-41db-afb0-6c6f5e78c7o7", 
    "referenceNumber": "21101218302348116184", 
    "tokenHMAC": "SGkhIEknbSBhbiBleGFtcGxlIHRva2VuSE1BQw==", 
    "cvvIncluded": false, 
    "cardType": "masterCard" 
}

HTTP Method: POST 
Content-Type: application/x-www-form-urlencoded

threeDSMethodData=eyJ0aHJlZURTTWV0aG9kTm90aWZpY2F0aW9uVVJMIjoiaHR0cHM6Ly9ub3RpZmljYXRpb24ucmVjZWlwdC1lbmRwb2ludC5vcmcvbm90aWZpY2F0aW9ucyIsInRocmVlRFNTZXJ2ZXJUcmFuc0lEIjoiZGUxMTllZGUtY2JlOC00MTE3LTgzNWEtYzZlYzMzZWE2MDJiIn0=

Failure Example

When device fingerprinting is not supported for a PAN or when another error occurs, a notice will be generated and the tokenize response's threeDSecureResponse will contain the error response. If device fingerprinting cannot be completed for a PAN, the Authentication request's MethodCompletionIndicator as 3 (unavailable).

{"type":"3DS Device Fingerprinting","success":false}

{ 
    "firstSix": "123456", 
    "lastFour": "1234", 
    "forterInitResponse": null, 
    "kHash": "", 
    "threeDSecureResponse": [ 
        { 
            "errorCode": "4006", 
            "errorDetail": "No EMV 3DS card ranges match submitted request", 
            "errorDescription": "No matching card range data", 
            "threeDSServerTransID": "b67906f0-2ad4-4d71-bd19-09d58fac82a0", 
            "errorComponent": "S" 
        } 
    ], 
    "token": "96d3b89g-16ab-41db-afb0-6c6f5e78c7o7", 
    "referenceNumber": "21101218302348116184", 
    "tokenHMAC": "SGkhIEknbSBhbiBleGFtcGxlIHRva2VuSE1BQw==", 
    "cvvIncluded": false, 
    "cardType": "masterCard" 
}

Outside the TokenEx iFrame

When a checkout flow does not include the TokenEx iFrame or more control is needed, follow the below steps to add device fingerprinting to the page.

1. Execute an API call to ThreeDSecure/SupportedVersions. If device fingerprinting is supported by the card issuer, the threeDSecureResponse will contain a threeDSMethodURL. Retrieve the threeDSMethodURL and the threeDSServerTransID from the response. If a threeDSMethodURL is not present, include MethodCompletionIndicator as 3 (unavailable) in the ThreeDSecure/Authentications request.
2. Post a form to the threeDSMethodURL. The form parameter is threeDSMethodData. The content of that parameter should be a base64-encoded json object containing the threeDSServerTransID and an endpoint to receive a notification (steps 2a and 2b below) when device fingerprinting is completed. A script will be returned.

{
  "threeDSMethodNotificationURL": "https://merchant-defined-webhook.merchant.com",
  "threeDSServerTransID": "52329f00-7951-4572-9432-356298fc300c"
}

threeDSMethodData:ew0KICAidGhyZWVEU01ldGhvZE5vdGlmaWNhdGlvblVSTCI6ICJodHRwczovL21lcmNoYW50LWRlZmluZWQtd2ViaG9vay5tZXJjaGFudC5jb20iLA0KICAidGhyZWVEU1NlcnZlclRyYW5zSUQiOiAiNTIzMjlmMDAtNzk1MS00NTcyLTk0MzItMzU2Mjk4ZmMzMDBjIg0KfQ==

<script>
	document.addEventListener("DOMContentLoaded", function () {
        var userAgent = window.navigator.userAgent;
        var form = document.createElement("form");
        form.method = "POST";
        form.action = "https://acs-public.tp.mastercard.com/api/v1/process_browser_attributes";
        form.appendChild(createInput("threeDSServerTransID", "4f0b1621-d950-42c8-bde1-6d760ff74868"));
        form.appendChild(createInput("deviceInfo", userAgent));
        document.body.appendChild(form);
        form.submit();
        document.body.removeChild(form);
    });

    function createInput(name, value) {
        var result = document.createElement("input");
        result.name = name;
        result.value = value;
        return result;
    }
</script>

3. Load that script into a hidden iframe within the customer's browser. This script (example above) will retrieve miscellaneous browser attributes of the card issuer's choice. The response to the above script is another script (example below) which upon execution will post to the merchant-defined threeDSMethodNotificationURL from Step 2a's JSON above.

<script>
	document.addEventListener("DOMContentLoaded", function () {
        var form = document.createElement("form");
        form.method = "POST";
        form.action = "https://merchant-defined-webhook.merchant.com";
        form.enctype = "application/x-www-form-urlencoded";
        form.appendChild(createInput("threeDSMethodData", "eyJ0aHJlZURTTWV0aG9kTm90aWZpY2F0aW9uVVJMIjoiaHR0cHM6Ly9tZXJjaGFudC1kZWZpbmVkLXdlYmhvb2subWVyY2hhbnQuY29tIiwidGhyZWVEU1NlcnZlclRyYW5zSUQiOiI0ZjBiMTYyMS1kOTUwLTQyYzgtYmRlMS02ZDc2MGZmNzQ4NjgifQ=="));
        document.body.appendChild(form);
        form.submit();
        document.body.removeChild(form);
    });

    function createInput(name, value) {
        var result = document.createElement("input");
        result.name = name;
        result.value = value;
        return result;
    }
</script>

HTTP Method: POST 
Content-Type: application/x-www-form-urlencoded

threeDSMethodData=eyJ0aHJlZURTTWV0aG9kTm90aWZpY2F0aW9uVVJMIjoiaHR0cHM6Ly9tZXJjaGFudC1kZWZpbmVkLXdlYmhvb2subWVyY2hhbnQuY29tIiwidGhyZWVEU1NlcnZlclRyYW5zSUQiOiI0ZjBiMTYyMS1kOTUwLTQyYzgtYmRlMS02ZDc2MGZmNzQ4NjgifQ==

4. Upon receipt of the notification, include MethodCompletionIndicator as 1 (successful) in the Authentications request. If the notification is not received within 10 seconds of the script execution in Step 3, close the hidden iframe and include MethodCompletionIndicator as 2 (not successful) in the Authentications request.

The threeDSServerTransIDshould then be used within the ThreeDSecure/Authentications request in the ServerTransactionId field and the ACS will take the browser attributes into account when determining whether to issue a challenge.

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PCI DSS 4.0 Requirements for Payment Page Scripts

While the PCI DSS 4.0 Requirement 6.4.3 to inventory and verify integrity of scripts executed on a payment page goes into effect on the 31st of March 2025, the scripts performing 3DS functionality are not subject to that requirement. More information can be found on the PCI SSC website.