Augmented Zero-Knowledge Proofs with OPRF-Based Private Membership

The patent introduces an intermediary mechanism using oblivious pseudo-random functions (OPRF) and trusted execution environments (TEEs). The verifier's check list is transformed into encrypted representations within a TEE, allowing membership testing without direct disclosure of the list contents. This intermediary computational layer enables the verifier to perform membership tests while maintaining list privacy, resolving the contradiction between verifier privacy and membership test capability.

The patent transforms the verifier's check list from plaintext identifiers into encrypted representations using OPRF with unique salts for each entry. This parameter transformation allows the system to perform membership testing on encrypted data within TEEs, enabling the verifier to maintain list privacy while still performing accurate membership tests. The change in data representation form resolves the contradiction by making the list unusable for direct inspection while preserving its functional utility.

The patent uses TEEs as an intermediary trusted computing environment that holds the verifier's secret check list. The TEE performs membership testing operations without exposing the list contents to either the user or external observers. This intermediary ensures that membership test reliability is maintained through cryptographic verification while the list remains secret within the trusted boundary, resolving the contradiction between list secrecy and test reliability.

The patent replaces the traditional mechanical approach of direct list disclosure and comparison with cryptographic substitution using OPRF and TEEs. Instead of mechanically comparing plaintext lists, the system uses cryptographic transformations and trusted execution to perform membership testing. This substitution maintains list secrecy while ensuring reliable membership determination through cryptographic proof mechanisms.

The patent segments the authentication process into multiple independent cryptographic interactions using unique salts for each OPRF evaluation. Each verifier interaction uses distinct cryptographic parameters, making it computationally infeasible to link authentication events across different verifiers. This segmentation of the authentication process into isolated cryptographic sessions enables unlinkable authentication while maintaining user identity privacy.

The patent adds a new dimension to anonymous credential systems by integrating OPRF-based membership testing with TEEs. This dimensional extension allows the system to simultaneously achieve unlinkable authentication across multiple verifiers and private membership testing, going beyond the capabilities of traditional anonymous credential systems. The additional cryptographic layer enables these advanced privacy features without compromising user identity protection.