Ad audiences hashing

When you want to target customers on advertising platforms like Meta, Google with your customer data, you need to protect their privacy while maintaining campaign effectiveness.

Ad audience hashing enables privacy-safe customer targeting across major advertising platforms. With Bloomreach Engagement, we handle the technical complexity automatically through the Ad audiences integration.

For marketing teams, this means you can focus on campaign strategy while the platform handles privacy compliance and technical implementation behind the scenes.

What is ad audience hashing?

Hashing converts personal data like email addresses or phone numbers into irreversible, fixed-length codes using mathematical algorithms. The most common algorithm is SHA-256, which creates a unique 64-character code for each piece of data. This is a one-way transformation that you can't undo.

Example transformation:

• Original email: [email protected]
• Hashed version: 6dcd4ce23d88e2ee9568ba546c007c63cfb80bc35ac28df4b236b4f495383a4a

The key advantage is that advertising platforms hash their own user data the same way. When you upload hashed customer lists, platforms can match these codes to find your customers without seeing their actual personal information. Proper data normalization (converting to lowercase, removing spaces, and special characters) before hashing is crucial for maximizing match rates and is built into automated workflows.

Proper data normalization (converting to lowercase, removing spaces and special characters) before hashing is crucial for maximizing match rates and is built into automated workflows.

If the customer doesn’t match, vendors delete the data as per their terms and conditions:

• Google
• Meta

Why you need ad audience hashing

Protect customer privacy

Hashing prevents advertising platforms, vendors, or anyone who intercepts data transfers from accessing your customers' actual personal information. This protects both your customers and your business from data breaches or misuse.

Stay compliant

Privacy laws like GDPR and CCPA require appropriate security measures and encourage pseudonymization when handling personal data. Hashing is a best practice and platform policy that helps meet these requirements. This demonstrates data minimization - you're only sharing what's necessary in the safest format.

Maintain campaign performance

Hashed audiences can maintain targeting effectiveness while staying compliant. You can use hashed audiences for targeting, lookalike modeling, and exclusion campaigns (to suppress ads to certain customer groups).

This approach allows you to serve personalized offers to specific customer segments - for example, targeting high-value customers who made purchases over €1,000 in the past year with exclusive promotions visible only to this group.

Build customer trust

When customers know their personal information is protected through secure practices, they're more likely to engage with your brand and share data for personalized experiences.

How hashing works with Bloomreach Engagement

Ad audiences module

In Bloomreach Engagement, you create scenarios where the final action uses the "Ad Audiences" node. This node integrates with multiple advertising providers and automatically handles the hashing process.

Example workflow

• Create a scenario that identifies high-value customers. For example, purchases over €1,000 in the past year.
• Add an "Ad Audiences" node as the final action.
• Select your integration (advertising provider) and target audience list.

When customers meet your criteria, Bloomreach Engagement automatically:

• Encrypts their data using hash codes.
• Transfers only the hashed codes to the advertising platform.
• Enables the platform to match users without accessing raw data.

Data handling process

• Email addresses are hashed using SHA-256.
• Phone numbers have country codes and special characters removed, then hashed with SHA-256.
• Mobile advertising IDs (IDFA for Apple, Android Advertising ID) are sent without hashing.
• External IDs aren't supported by Meta.

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Note

The Facebook Pixel does not enter into this process in any way. The ad audiences integration works independently of pixel-based tracking.

The contractual relationship between Bloomreach and advertising providers is governed by Bloomreach's terms for 3rd party integrations. Data handling on the advertising platform side follows their privacy policies, with Meta being certified under the Data Protection Framework (DPF) as of September 2023.

Best practices for implementation

Before syncing audiences

• Hash at the source - never upload raw customer data.
• Normalize data first - remove spaces, convert emails to lowercase, standardize phone formats.
• Include only essential identifiers - email and phone numbers, not addresses or other unnecessary details.

During setup

• Use SHA-256 hashing for platform compatibility.
• Verify each platform's specific formatting requirements.
• Document your hashing procedures for compliance audits.

For ongoing compliance

• Update privacy policies to include audience hashing disclosures if required.
• Honor opt-out requests across all advertising platforms.
• Review platform requirements quarterly, as they can change.

Data handling standards

• Use secure transfer protocols (API, SFTP) for audience uploads.
• Maintain audit trails of hashing and sync actions.
• Limit access to hashed audience data on a need-to-know basis.

Platform-specific considerations

Different advertising platforms have varying requirements for hashed audiences:

Meta (Facebook/Instagram)

• Requires SHA-256 hashing for emails and phone numbers.
• Automatically deletes matched and unmatched hash information after creating custom audiences.
• Supports email, phone, and mobile advertising ID matching.

Google Ads

• Accepts SHA-256 hashed emails and phone numbers.
• Requires specific data formatting for optimal match rates.
• Offers Customer Match for remarketing and lookalike modeling.

Other platforms

• Each platform has specific hashing and formatting requirements.
• Bloomreach Engagement integrations handle these variations automatically.
• Always verify requirements when setting up new platform connections.