There are many situations in which it is desirable to take measurements of data which people consider sensitive. For instance, a browser company might want to measure web sites that do not render properly without learning which users visit those sites, or a public health authority might want to measure exposure to some disease without learning the identities of those exposed. In these cases, the entity taking the measurement is not interested in people's individual responses but rather in aggregated data (e.g., how many users had errors on site X). Conventional methods require collecting individual measurements and then aggregating them, thus representing a threat to user privacy and rendering many such measurements difficult and impractical.

New cryptographic techniques address this gap by splitting measurements between multiple, non-colluding servers which can jointly compute the aggregate value without either server learning the value of individual measurements. The Privacy Respecting Incorporation of Values (PRIV) work will standardize protocols for deployment of these techniques on the Internet. This will include mechanisms for:

- Client submission of individual measurements, including proofs of validity
- Verification of validity proofs by the servers
- Computation of aggregate values by the servers and reporting of results to the entity taking the measurement

A successful PRIV system assumes that clients and the various servers are configured with each other's identities and details of the types of measurements to be taken. This is assumed to happen out of band and will not be standardized in this working group.

The WG will deliver one or more protocols which can accommodate multiple PRIV algorithms. The initial deliverables will support the calculation of simple predefined statistical aggregates such as averages, as well as calculations of the values that most frequently appear in individual measurements. The PRIV protocols will use cryptographic algorithms defined by the CFRG.

The starting point for PRIV WG discussions shall be draft-gpew-priv-ppm.