How we protect phone numbers using Oblivious Pseudorandom Function

In this article, Yandex information security expert Aidar Sabirov describes a technical solution for complying with legal requirements that mandate audiovisual services to share user identifiers with a government-authorized research organization. The challenge was to create a unified identifier based on phone numbers without exposing the numbers themselves or creating a single point of data compromise. Instead of simple hashing with a shared secret, which posed security risks for dozens of independent companies, the team implemented a scheme based on the Oblivious Pseudorandom Function (OPRF). This cryptographic approach allows for the generation of consistent identifiers while maintaining the privacy of the original data. The author emphasizes that the project required not only complex mathematical calculations but also the establishment of an industry-wide process for collaboration among market participants to ensure the protection of user personal data.