When it comes to securing test data, encryption is commonly used to protect sensitive data. But standard encryption techniques aren’t able to adapt their output to fit specific formats and schemas. This limits the application of encryption because data that breaks formats, breaks systems. Input validations fail, schemas reject new entries, and test environments stop mimicking production. Format-preserving encryption (FPE) addresses this challenge by securing sensitive data in a way that preserves structure and continuity across your systems.
With FPE, you can protect your data without triggering problems with the systems that rely on its format, from front-end validation to backend schema integrity. That rare combination of usability and security makes it a solution worth exploring.
Understanding format-preserving encryption (FPE)
FPE uses standardized, NIST-endorsed algorithms such as FF1 and FF3-1 to transform data while preserving the format of the input.
For example, the SSN 123-45-6789 could be encrypted as 529-38-1746 — a valid-looking SSN that meets length and format requirements but reveals nothing about the original data. This preserves interoperability across systems while minimizing the engineering lift.
You can rely on FPE to support legacy systems, structured identifiers, and critical business applications. Unlike tokenization, which often requires managing mapping tables or reengineering validation logic, FPE keeps the data "in shape" — which means fewer bugs, faster testing, and better audit outcomes.
FPE also supports determinism: the same input will always yield the same encrypted output. This is crucial for maintaining referential integrity across tables, especially when masking data for integration testing or analytics.
The benefits of FPE
The real power of format-preserving encryption lies in how seamlessly it supports the demands of modern data workflows. It protects sensitive information while keeping systems functional, teams aligned, and compliance efforts streamlined.
- Preserving data integrity: Because FPE retains the original format, it avoids breaking schema constraints, application logic, or data validation rules.
- Protecting primary keys: By preserving the data’s integrity, format-preserving encryption makes it possible to protect primary keys—a requirement that is very difficult to fulfill by way of other approaches to data de-identification.
- Realistic testing: Format-preserved data can be used in non-production environments, enabling realistic testing without exposing real user information.
- Improved usability: You don’t have to rewrite interfaces, update regex patterns, or handle edge-case formatting errors.
- Enhanced security: Field-level encryption works without requiring decryption for processing, reducing risk exposure.
- Regulatory compliance: It helps meet standards like HIPAA, PCI DSS, and GDPR with audit-friendly, field-level protection.
- Ease of integration: Native encryption libraries can be hard to use or brittle; FPE tools that abstract this process improve dev velocity.
- Minimized system friction: FPE integrates into existing workflows without the overhead of managing token vaults or building custom de-tokenization logic.
Format-preserving encryption in the real world
FPE already plays a critical role in securing data across sectors, from finance to healthcare. Here's how it's being used in practice:
Financial services
You can use FPE to encrypt account and credit card numbers while maintaining their format. Since these formats are tied to payment processing rules, keeping the structure intact means systems like fraud detection and transaction auditing continue to operate as expected, without needing to decrypt the data.
Healthcare
FPE protects patient identifiers and SSNs while preserving interoperability between systems. This simplifies compliance with HIPAA and other health data regulations. You can use FPE to ensure that clinical systems, lab integrations, and administrative portals all continue functioning correctly even when working with masked or encrypted patient records.
Insurance
Insurers can encrypt policy numbers and claims data to support software testing in non-production environments without requiring decryption. With FPE, your data stays encrypted throughout the whole process without breaking your app’s logic during testing. You can run simulations, automate quote engines, or execute claims models with production-like fidelity while safeguarding private data.
Government
Legacy systems often can't tolerate schema changes. With FPE, agencies can secure sensitive data without rewriting COBOL-based workflows. This is especially valuable when updates must be made across distributed systems with limited development resources or when policy timelines require fast implementation.
E-commerce
You can encrypt customer emails, phone numbers, and addresses to protect privacy while maintaining compatibility with transactional and shipping systems. FPE lets customer service and order fulfillment teams work with data that behaves exactly like the real thing, while eliminating the liability of handling sensitive user information.
How to implement format-preserving encryption
With Tonic Structural, Tonic.ai’s platform for structured data de-identification, implementing FPE is streamlined and developer-friendly — no cryptographic PhD required.
Step 1. Create a Tonic Structural account
Sign up for a free trial or enterprise account to begin using FPE-enabled data generation tools.
Step 2. Connect to your data
Connect to your production-like datasets via native integrations for sources such as PostgreSQL, MySQL, or Snowflake.
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Step 3. Apply FPE generators
Assign format-preserving encryption generators to relevant fields. If you see encryption errors, it probably means the column contains values that are incompatible with the selected generator. To address this, you need to choose a different generator, either the ASCII Key generator (very few restrictions) or the Conditional generator (based on column values).
Step 4. Configure a destination database
Select a target output, whether it's a cloud database, on-prem instance, or local file, to store the generated (encrypted) dataset.
Step 5. Run data generation
Start the generation process. Tonic Structural applies FPE to the designated fields, giving you a safe, schema-consistent version of your dataset for testing or sharing.
Leverage format-preserving encryption in Tonic Structural
Format-preserving encryption satisfies both technical and compliance demands without slowing you down. It’s fast, invisible, and secure by design.
Tonic Structural makes implementing format-preserving encryption intuitive and scalable. Whether you’re testing an app, staging a migration, or navigating a compliance audit, Structural helps you protect your data while preserving the shape of your systems.
Connect with our team to explore how Tonic.ai can help you accelerate development and optimize testing with secure, usable data today.
