libprio-rs

Pure Rust implementation of Prio, a system for Private, Robust, and Scalable Computation of Aggregate Statistics.

Exposure Notifications Private Analytics

This crate was used in the Exposure Notifications Private Analytics system. This is referred to in various places as Prio v2. See prio-server or the ENPA whitepaper for more details.

Verifiable Distributed Aggregation Function

This crate also implements a Verifiable Distributed Aggregation Function (VDAF) called "Prio3", implemented in the vdaf module, allowing Prio to be used in the Distributed Aggregation Protocol protocol being developed in the PPM working group at the IETF. This support is still evolving along with the DAP and VDAF specifications.

Draft versions and release branches

The main branch is under continuous development and will usually be partway between VDAF drafts. libprio uses stable release branches to maintain implementations of different VDAF draft versions. Crate prio version x.y.z is released from a corresponding release/x.y branch. We try to maintain Rust SemVer compatibility, meaning that API breaks only happen on minor version increases (e.g., 0.10 to 0.11).

Crate version	Git branch	VDAF draft version	DAP draft version	Conforms to specification?	Status
0.8	release/0.8	draft-irtf-cfrg-vdaf-01	draft-ietf-ppm-dap-01	Yes	Unmaintained as of March 28, 2023
0.9	release/0.9	draft-irtf-cfrg-vdaf-03	draft-ietf-ppm-dap-02 and draft-ietf-ppm-dap-03	Yes	Unmaintained as of September 22, 2022
0.10	release/0.10	draft-irtf-cfrg-vdaf-03	draft-ietf-ppm-dap-02 and draft-ietf-ppm-dap-03	Yes	Supported
0.11	release/0.11	draft-irtf-cfrg-vdaf-04	N/A	Yes	Unmaintained
0.12	release/0.12	draft-irtf-cfrg-vdaf-05	draft-ietf-ppm-dap-04	Yes	Supported
0.13	release/0.13	draft-irtf-cfrg-vdaf-06	draft-ietf-ppm-dap-05	Yes	Unmaintained
0.14	release/0.14	draft-irtf-cfrg-vdaf-06	draft-ietf-ppm-dap-05	Yes	Unmaintained
0.15	main	draft-irtf-cfrg-vdaf-07	draft-ietf-ppm-dap-06	Yes	Supported

Cargo Features

This crate defines the following feature flags:

Name	Default feature?	Description
crypto-dependencies	Yes	Enables dependencies on various RustCrypto crates, and uses them to implement XofShake128 to support VDAFs.
experimental	No	Certain experimental APIs are guarded by this feature. They may undergo breaking changes in future patch releases, as an exception to semantic versioning.
multithreaded	No	Enables certain Prio3 VDAF implementations that use rayon for parallelization of gadget evaluations.
prio2	No	Enables the Prio v2 API, and a VDAF based on the Prio2 system.