Information processing apparatus and information processing method

An information processing apparatus, comprising:

• an encrypting unit configured to generate an encrypted bit string in which a hash value calculated by using keyed hashing from a keyword for an information search is mapped into a bit string having a predetermined length;
• a bit inverting unit configured to select a predetermined number of bits from the encrypted bit string on a basis of a dynamically generated random number, and invert the predetermined number of selected bits;
• a communicating unit configured to receive, as a search result, encrypted inverted-bit-number information corresponding to an encrypted index in which the predetermined number of bits are inverted, the encrypted index corresponding to a sent encrypted keyword;
• and
• a decrypting unit configured to generate inverted-bit-number information before encryption on a basis of the encrypted inverted-bit-number information, wherein
• the communication is further configured to send the encrypted bit string and the inverted-bit-number information to an external apparatus, the inverted-bit-number information indicating a number of bits inverted by the bit inverting unit, and
• the decrypting unit is further configured to calculate logical AND of the encrypted keyword and the inverted-bit-number information before the encryption to determine whether or not the search result includes an erroneous determination on a basis of a result of the calculation.