| 摘要 |
PROBLEM TO BE SOLVED: To provide a data transmission system wherein a receiver side can authenticate transmission data even when a third party in place of an original sender transmits the data and transmission by impersonation can be prevented, and to provide a data transmission method and apparatus. SOLUTION: A data transmission system S is provided with an ID chip 1, an ID card 2, and a card reader 3. The ID chip 1 transmits start signals (C<SB>1</SB>, C<SB>2</SB>) to the ID card 2, and when the start signals (C<SB>1</SB>, C<SB>2</SB>) are authenticated, the ID card 2 transmits authentication signals (S<SB>1</SB>, S<SB>2</SB>) to the card reader 3. When the card reader 3 authenticates the authentication signals, the card reader 3 transmits an output signal to an external device 4. An ID number encrypted by the combination of conversion constants y(Y) and z'(Z') and a conversion constant x(X) are included in one of the start signals (authentication signals), and an ID number encrypted by the conversion constants y(Y) and z'(Z') and a pattern conversion constant z(Z) in association with the conversion constants y(Y) and z'(Z') are included in the other start signals (authentication signals) and the resulting start signals (authentication signals) are transmitted. COPYRIGHT: (C)2005,JPO&NCIPI
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