TCF Control Module

Until Prebid.js 9.0 this was known as the “GDPR Enforcement” module.

• Overview
• Page Integration
  • Examples
• Basic Legal Basis
  • Note on Extended User IDs
• Build the Package
• Further Reading

This module requires the TCF consent management module (the base consent module), which reads consent values from the Consent Management Platform (CMP). The TCF Control Module will then take action based on the results. See the base module page for general background, usage, and legal disclaimers.

Overview

The base consent module performs the following actions:

1. Fetches the user’s GDPR consent data from the CMP.
2. Incorporates this data into the auction objects for adapters to collect.

The TCF Control Module adds the following:

1. Allows the page to define which activities should be restricted at the Prebid.js level.
2. Actively restricts those activities based on user consent data.

The following table details the Prebid.js activities that fall under the Transparency and Consent Framework (TCF) scope:

Page Integration

A page needs to define configuration rules about how Prebid.js should restricts each in-scope activity.

Important Legal Note: Prebid.org cannot provide legal advice about GDPR or any other governmental regulation. Our aim is to provide a toolkit of functionality that will let publishers configure header bidding as defined by their legal counsel. We will consider feature suggestions, and review any code offered by the community.

To turn on Prebid.js restrictions you must:

(1) Include the tcfControl module in the Prebid.js build and (2) setConfig consentManagement.gdpr.cmpApi to either ‘iab’ or ‘static’

The following fields related to anonymizing aspects of the auction are supported in the consentManagement object:

Notes:

• By default, Prebid allows some limited use of storage even when purpose 1 consent was not given: this is limited to non-PII, such as category translation mappings, or temporary test data used to probe the browser’s storage features. If strictStorageEnforcement is true, Purpose 1 consent will always be enforced for any access to storage.
• To accomodate Prebid.js modules and adapters that don’t have GVL IDs, the vendorExceptions list is based on Prebid.js biddercodes instead of Global Vendor List (GVL) IDs (i.e. “bidderA” instead of “12345”).
• An alternate way of establishing a GVL mapping is to define a ‘gvlMapping’ object:

pbjs.setConfig({
    gvlMapping: {
    bidderA: 12345,
        bidderB: 67890
    }
});

Examples

The following examples cover a range of use cases and show how Prebid.js supports configuration of different business rules.

1. Restrict device access activity and basic ads. These are the default values (in Prebid.js 4.0) if the module is included in the build.

    pbjs.setConfig({
      consentManagement: {
        gdpr: {
          cmpApi: 'iab',   // activates the control module
          defaultGdprScope: true,
          rules: [{        // these are the default values
            purpose: "storage",
            enforcePurpose: true,
            enforceVendor: true
          },{
            purpose: "basicAds",
            enforcePurpose: true,
            enforceVendor: true
          },{
            purpose: "personalizedAds",
            enforcePurpose: true,
            enforceVendor: true
          },{
            purpose: "measurement",
            enforcePurpose: true,
            enforceVendor: true
          },{
            purpose: "transmitPreciseGeo",
            enforcePurpose: true
          }]
        }
      }
    });
   

2. Restrict that the user consents to DeviceAccess as an activity and consider their per-vendor selection. However, idSystemA is a special case - the publisher has confirmed that this system obtains a user ID every auction and does not write to the local device.

      ...
      rules: [{
        purpose: "storage",
        enforcePurpose: true,
        enforceVendor: true,
        vendorExceptions: ["idSystemA"]
      }]
   

3. Restrict for both storage and basicAds, with the exception of “firstPartyBidder”, which is always allowed to run an auction. Assumes the publisher has special legal basis for this entity.

      ...
      rules: [{
        purpose: "storage",
        enforcePurpose: true,
        enforceVendor: true
      },{
    purpose: "basicAds",
    enforcePurpose: true,
    enforceVendor: true,
        vendorExceptions: ["firstPartyBidder"]
      }]
   

4. Turn off restriction of Purpose 1: don’t enforce either the user’s DeviceAccess consent or their per-vendor selection.

      ...
      rules: [{
        purpose: "storage",
        enforcePurpose: false,
        enforceVendor: false
      }]
   

5. Allow the user to suppress analtyics provider A, but make an exception for analytics provider B.

      ...
      rules: [{
        purpose: "measurement",
        enforcePurpose: true,
        enforceVendor: true,
    vendorExceptions: ["analyticsB"]
      }]
   

Basic Legal Basis

Prebid.js does not have access to the Global Vendor List (GVL), so it implements a “basic” form of TCF ‘legal basis’ validation using the supplied consent string.

A goal of ‘basic legal basis’ is to confirm that there’s enough evidence of consent to pass data on to vendors who do have access to the GVL and can fully parse and take any necessary action.

Evidence of consent for a particular purpose or vendor means that:

• Prebid.js has the the user’s purpose or vendor consent, or
• (for Purpose 2 only) we’ve confirmed the user’s Legitimate Intereset (LI) Transparency is established for this purpose or vendor.

Before allowing an activity tied to a TCF-protected Purpose for a given vendor, one of these scenarios must be true:

• Configuration rules check both consent and vendor signals and:
  • we have evidence of consent for both, or
  • we have evidence of consent for the purpose, and the vendor is excepted through softVendorException, or
  • the vendor is excepted through vendorExceptions;
• Configuration rules check only purpose consent and either:
  • we have evidence of consent for the purpose, or
  • the vendor is excepted through vendorExceptions;
• Configuration rules check only vendor signals and either:
  • we have evidence of consent for the vendor, or
  • the vendor is excepted through either softVendorExceptions or vendorExceptions;
• Configuration rules check neither purpose consent nor vendor signal.

See the IAB TCF Consent String Format for details.

Note on Extended User IDs

Note: the default of the eidsRequireP4Consent flag may change from false to true in a future major release.

By default, sending user IDs and EIDs to bid adapters or RTD modules (the transmitEids activity) is not tied to a single TCF Purpose; instead it is allowed if one of these scenarios is true:

• We have evidence of consent for the vendor and evidence of consent for any purpose between 2 and 10;
• We have evidence of consent for any purpose between 2 and 10, and the vendor is excepted through softVendorException in at least one of: basicAds, personalizedAds, or measurement;
• The vendor is excepted through vendorExceptions in at least one of basicAds, personalizedAds, or measurement.

This behavior can be changed to the same “basic legal basis” algorithm described above, tied to TCF Purpose 4, by setting eidsRequireP4Consent: true on a personalizedAds rule:

  ...
  rules: [{
    purpose: "personalizedAds",
    eidsRequireP4Consent: true
  }]

Build the Package

Follow the basic build instructions in the GitHub Prebid.js repo’s main README. Include the base consent management module and this control module as additional options on the gulp build command:

gulp build --modules=consentManagement,tcfControl,bidAdapter1,bidAdapter2

You can also use the Prebid.js Download page.

Further Reading

• EU GDPR Consent Management Module
• IAB TCF Implementation Guidelines
• IAB TCF2 Consent String Format
• Prebid TCF2 Support
• CMP Best Practices