Authentication apparatus and method for clustering and authenticating users

An authentication method performed by a computer comprising:

• acquiring a plurality of pieces of different context information on a plurality of users, including a target user, which is a target for authentication;
• performing a first clustering by clustering groups of users of the plurality of users into a plurality of cluster groups based on information related to the plurality of cluster groups, each of the plurality of cluster groups being formed based on the plurality of different context information related to the groups of users of the plurality of users;
• performing a second clustering by specifying and clustering sub-sets of the plurality of users from each of the plurality of cluster groups of users to form a plurality of belonging clusters of users, one of the plurality of belonging clusters including the target user, the second clustering performed in each of the plurality of cluster groups being performed on a candidate user group of the plurality of users that becomes a candidate for authentication based on a type related to an element included in the context information and based on the acquired context information on the target user;
• performing a third clustering by specifying and clustering a plurality of candidate users that satisfy a predetermined condition from the plurality of belonging clusters, each of the plurality of candidate users being from a respective partial candidate user group of each of the specified belonging clusters, each candidate user of the plurality of candidate users being specified based on (i) applying a classification model to specify a predetermined candidate user in the partial candidate user group of the specified belonging cluster, and (ii) the acquired context information on the target user;
• and
• authenticating the target user based on information related to the specified candidate user associated with each of the plurality of the cluster groups.

A non-transitory computer-readable recording medium having stored therein an authentication program that causes a computer to execute a process comprising:

• acquiring a plurality of pieces of different context information on a plurality of users, including a target user, which is a target for authentication;
• performing a first clustering by clustering groups of users of the plurality of users into a plurality of cluster groups based on information related to the plurality of cluster groups, each of the plurality of cluster groups being formed based on the plurality of different context information related to the groups of users of the plurality of users;
• performing a second clustering by specifying and clustering sub-sets of the plurality of users from each of the plurality of cluster groups of users to form a plurality of belonging clusters of users, one of the plurality of belonging clusters including the target user, the second clustering performed in each of the plurality of cluster groups being performed on a candidate user group of the plurality of users that becomes a candidate for authentication based on a type related to an element included in the context information and based on the acquired context information on the target user;
• performing a third clustering by specifying and clustering a plurality of candidate users that satisfy a predetermined condition from the plurality of belonging clusters, each of the plurality of candidate users being from a respective partial candidate user group of each of the specified belonging clusters, each candidate user of the plurality of candidate users being specified based on (i) applying a classification model to specify a predetermined candidate user in the partial candidate user group of the specified belonging cluster, and (ii) the acquired context information on the target user;
• and
• authenticating the target user based on information related to the specified candidate user associated with each of the plurality of the cluster groups.