Re-identification

A mechanism by which a previously anonymous or pseudonymous App User can be identified with high certainty.

Re-identification can be accomplished in a variety of settings. Here are some examples:

• a previously anonymous or pseudonymous App User may voluntarily state their legal name and address;
• because only one App User was present at a certain place and time, a photograph of that place and time may show enough information about the App User (e.g. face, car’s number plate and the like) to be sufficient to re-identify the App User.
• the location history of an App User over a period of some days or weeks may be sufficiently unique to identify them uniquely from among others.

See also Wikipedia entry on data re-identification.