Encryption system, encryption method and encryption device

An encryption method executed by an encryption device and a decryption device, the method comprising:

• by the encryption device:
• encoding at least a part of items of data, including a plurality of records having a plurality of items with a unit of items of respective records, so that a code becomes unique in a unit of items, creating an encoded dictionary in which a code allocated with the unit of items and the data are associated with each other;
• creating an encrypted dictionary in which the encoded dictionary having been used at the encoding is encrypted with a different encryption key per a unit of dictionary;
• and
• transmitting, according to a request for a part of records included in the data, the encoded part of records and the encrypted dictionary to a requesting source;
• and
• by the decryption device:
• requesting a part of records included in the data to the encryption device;
• and
• decrypting the part of records received from the encryption device according to the request by using the encrypted dictionary.

An encryption device comprising:

• a processor that executes a process including:
• encoding at least a part of items, of data including a plurality of records having a plurality of items with a unit of items of respective records, so that a code becomes unique in a unit of items, creating an encoded dictionary in which a code allocated with the unit of items and the data are associated with each other;
• creating an encrypted dictionary in which the dictionary having been used at the encoding is encrypted with a different encryption key per a unit of dictionary;
• and
• transmitting, according to a request for a part of records included in the data, the encoded part of records and the encrypted dictionary to a requesting source.

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

• encoding at least a part of items of data, including a plurality of records having a plurality of items with a unit of items of respective records, so that a code becomes unique in a unit of items, creating an encoded dictionary in which a code allocated with the unit of items and the data are associated with each other;
• creating an encrypted dictionary in which the dictionary having been used at the encoding is encrypted with a different encryption key per a unit of dictionary;
• and
• transmitting, according to a request for a part of records included in the data, the encoded part of records and the encrypted dictionary to a requesting source.