ENCRYPTION PROCESSING SYSTEM

摘要

PROBLEM TO BE SOLVED: To improve security by reducing the possibility that a correspondence relation between data to be a source of encryption and encrypted data is intercepted by an illegal method.

SOLUTION: A reader/writer transmits an encryption command (a) including plaintext data to an IC card to make encryption processing to be carried out in the IC card, and an encrypted sentence is made to be returned as a response. In such a case, the obtained encrypted sentence is divided to prepare a plurality of blocks 21 to 23, and the blocks are distributed to a plurality of responses to be returned. The reader/writer gives return request commands (c) and (e) until all of the blocks are returned. The IC card includes the remaining blocks in responses (d) and (f) and returns the responses. The number of divided blocks and the data length of each block are determined at random and a return order is also determined at random.

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