Data encoded by replacing each of a plurality of characters with bit strings is received. On the basis of definition information, at least one of the characters is recorded as corresponding to each of the bit lengths, and decode information is generated based on the number of characters, wherein the decode information includes bit string information for sorting the bit strings in a bit length order that is a predetermined order associated with bit lengths. In response to receiving a particular bit length, character information in which the characters are sorted in the bit length order is generated by inserting a character corresponding to the particular bit length into a position corresponding to the particular bit length in an array in which at least one of the bit lengths.