Google open-sources a zero-knowledge proof library that lets you prove you're over 18 without giving any information to websites or apps

Google has open-sourced its zero-knowledge proof library, Longfellow , which allows developers to verify a user's age while preserving privacy.

Now open source: our Zero-Knowledge Proof (ZKP) libraries for age assurance
https://blog.google/technology/safety-security/opening-up-zero-knowledge-proof-technology-to-promote-privacy-in-age-assurance/

In countries around the world, there is a growing movement to require website and app developers to implement age verification functions as a means of protecting children's safety. For example, the EU is working on establishing a unified framework for age verification, and France is calling for a ban on the use of social networking sites by people under the age of 15, highlighting the importance of age verification.

When presenting identification to a website or app to verify age, information other than age is also revealed, raising the risk of privacy violations and information leaks. For this reason, the EU plans to issue recommended regulations in 2026 for age verification methods using a technology called ' zero-knowledge proof ,' which can verify age without disclosing personal information.

Longfellow, developed by Google, is a library that enables 'age verification using zero-knowledge proof technology' as required by the EU and other standards. Websites and apps that use Longfellow will be able to prove that they are over the age limit without disclosing personal information such as ID cards.

Longfellow is available in the following GitHub repository, and developers can introduce age verification methods using zero-knowledge proof technology into their own products. In addition, at the time of writing, a security audit of Longfellow is also underway, and the audit results are scheduled to be released on August 1, 2025.

GitHub - google/longfellow-zk: Implementation of the Google Zero-Knowledge library for Identity Protocols.
https://github.com/google/longfellow-zk