Personal safety verification system and similarity search method for data encrypted for confidentiality

摘要

Disclosed is a system whereby it is possible to verify the safety of a person even if the person is not aware that the person is being searched for as a missing person. In this system, each verification requesting person who is searching for another person registers, in a database of a portal server (4), a set comprising a feature value of the face of the searched-for person and personal information (e.g., telephone number) about the searched-for person or the verification requesting person. A field server (2) constantly compares feature values of captured face images with the database, and if a close match is found between the feature value of a captured face image and the stored feature value of the face of a person, the field server (2) presents the registered personal information associated with that person to the person from which the captured face image was derived and requests verification from the latter person. Since the system is open to the public, the feature values stored in the database are protected by a template protection scheme. For example, random projections which differ with different locality-sensitive hash values of feature values are used so that it can be assumed that, in the vicinity of a target feature value, a local distance-preserving mapping is established between feature values and the corresponding protected feature values.