Patent attributes
An information processing apparatus includes: a storage unit that stores a tree structure formed by nodes, each of which is stores identification information identifying a document; and a registration unit that registers documents in the storage unit. The registration unit receives a document including identification information identifying the document and a word set and a key, registers the identification information in a leaf node in the tree structure, and calculates a secure index corresponding to identification information registered in each node from a root node to the leaf node in the tree structure based on the word set and the key. In addition, the registration unit generates a value calculated by adding the calculated secure index as a search index for the document and stores a value calculated by adding a search index generated for each of a plurality of received documents as a search index for the plurality of documents in the storage unit.
