Writing IA data to a user device

IA uses information about a device to measure the risk of an access event. To perform this assessment, IA may store data in cookies and local storage on the device. This information is securely stored on the device and the Symantec servers, in an encrypted format. The VIP IA JavaScript can be used to update the IA data that is stored on a user device with new data that is retrieved by an
evaluateRisk
call. Use the
IaDfp.writeTag()
function to update any device tag data which IA has stored on the device, and which IA may have used to help in recognizing the device.
If a
device.tag
key value pair is returned in the evaluateRisk response, the value can be written to the device using the
IaDfp.writeTag()
function. For example, you might use the
IaDfp.writeTag()
function to update device tag data to re-issue a tag to maintain or re-establish the tag association for the device if the device was recognized using a canvas match or enhanced match rather than a tag match.
Refer to Updating a JavaScript to challenge a user for instructions on updating a device tag the first time that you issue a device tag for a Remembered Device.
Once a tag is written to the device, subsequent
IaDfp.readFingerprint
calls read the tag and encode it in the device fingerprint to ease in recognizing the device.
To update or reestablish device tag data, invoke the
IaDfp.writeTag()
function as shown in the following example. If you set the parent domain using the
IaDfp.setParentDomain
method, set the parent domain before writing the tag. Use the correct domain for your application.
The
tag.value
parameter that is used in the
writeTag
call should be the value of the
device.tag
field that is returned from the
evaluateRisk
call. The
true
parameter in the
writeTag
call remembers the device by persisting the
tag
value on the device. Persistence occurs only if the device allows writing to local storage and the device is not in incognito browsing mode.
<!-- Include VIP IA JavaScript Library --> <script type="text/javascript" src="https://userservices.vip.symantec.com/vipuserservices/static/v_1_0/scripts/iadfp_1.3.js"></script <!-- If you set the parent domain prior to originally writing a tag, also set the parent domain. Use the correct domain for your application. --> <script type="text/javascript">IaDfp.setParentDomain(".base.domain.com")</script> <!-- Update IA data stored for the domain to the device --> <script type="text/javascript"> IaDfp.writeTag(tag.value, true);</script>