Consent-String-SDK-PHP

IAB Europe Transparency and Consent Framework (TCF) consent string decoder and encoder for PHP.

Decodes and encodes IAB Europe TCF consent strings, in both formats currently in circulation:

• TCF v2 TC String (C...), the format in force including the segment layout, publisher restrictions, and the disclosed vendors segment that TCF v2.3 made mandatory
• TCF v1.1 consent string (B...), sunset in 2020, kept for reading strings still stored in the wild

Quality

Install

composer require mifefr/consent-string-sdk-php

Usage

Decoding

ConsentString::decode() reads the 6 bit version prefix and returns the model matching it, so you do not have to know the format in advance.

use Mifefr\ConsentString\ConsentString;

$consent = ConsentString::decode($_COOKIE['euconsent-v2']);
// Mifefr\ConsentString\TcfV2\TcString for a v2 string,
// Mifefr\ConsentString\ConsentCookie for a v1 one

Reading a TC String (TCF v2)

use Mifefr\ConsentString\TcfV2\TcString;

$tc = new TcString('CQXEyXAQXEyXAAHABDENBkFqAOAAAAwAAAqIAFCEABSAFAAQABgAJgAjoAIACA');

$tc->getCmpId();                          // 7
$tc->getConsentLanguage();                // 'EN'
$tc->getTcfPolicyVersion();               // 5
$tc->getPublisherCC();                    // 'FR'

$tc->hasPurposeConsent(1);                // true
$tc->hasPurposeLegitimateInterest(5);     // true
$tc->hasSpecialFeatureOptIn(3);           // true
$tc->hasVendorConsent(8);                 // true
$tc->hasVendorLegitimateInterest(19);     // true

Whether a vendor may process for a purpose is not an AND of two bits: a publisher can forbid a purpose outright, or force it onto one legal basis, whatever the vendor declared in the Global Vendor List.

$tc->isVendorAllowedForPurpose(8, 1);
$tc->isVendorAllowedForPurpose(8, 1, 'consent');
$tc->isVendorAllowedForPurpose(8, 1, 'legitimate_interest');

$tc->getPublisherRestriction(7, 8);

This SDK decodes the TC String only, it does not fetch the Global Vendor List, so it cannot know which legal basis a vendor declared. Pass $legal_basis when you know it.

Disclosed vendors

TCF v2.3 made the disclosed vendors segment mandatory, so that a vendor reading a legitimate interest bit at 0 can tell a user objection from a vendor that was never disclosed. A missing segment is therefore reported as null, not false.

$tc->hasDisclosedVendorsSegment();   // false for a pre-2.3 string
$tc->isVendorDisclosed(755);         // true, false, or null if no segment

Encoding

Every setter is fluent, and encoding a decoded string reproduces it bit for bit.

use Mifefr\ConsentString\TcfV2\TcString;
use Mifefr\ConsentString\TcfV2\PublisherRestriction;

$tc = new TcString();
$tc->setCmpId(92)
   ->setCmpVersion(3)
   ->setConsentLanguage('fr')
   ->setPublisherCC('FR')
   ->setVendorListVersion(250)
   ->setPurposesConsent([1, 2, 3, 4])
   ->setPurposesLegitimateInterest([7, 8])
   ->setVendorConsent([1, 2, 3, 755])
   ->setVendorLegitimateInterest([755])
   ->setDisclosedVendors([1, 2, 3, 755])
   ->addPublisherRestriction(
       new PublisherRestriction(7, PublisherRestriction::TYPE_REQUIRE_CONSENT, [755])
   );

echo $tc->toBase64();

Reading a legacy v1 string

use Mifefr\ConsentString\ConsentCookie;

$consent = new ConsentCookie('BOXhscYOXhscYACABDENAE4AAAAAwQgA');

$consent->getConsentLanguage();   // 'EN'
$consent->getPurposesAllowed();   // [1, 2, 3]
$consent->isVendorAllowed(3);     // true

ConsentCookie rejects anything that is not a version 1 string. The two formats share their first 132 bits, so decoding a v2 string as v1 used to return wrong purposes and vendors instead of failing.

Format reference

	TCF v1.1	TCF v2
Prefix	B	C
Structure	single segment	core[.disclosedVendors][.allowedVendors][.publisherTC]
Legal bases	one purpose set	consent and legitimate interest, separately
Publisher overrides	none	publisher restrictions
Status	sunset in 2020	v2.3 in force since 28 February 2026

The bit layouts come from the IAB Tech Lab consent string specification.

Requirements

PHP 5.6 or later. The test suite runs on PHP 7.3 to 8.4; the sources are syntax checked on 5.6 in CI.

License

Released under the MIT License (MIT). See LICENSE for more information.