| 摘要 |
PROBLEM TO BE SOLVED: To provide a communication method which is secure against attacks in various ways to senders. SOLUTION: A transmitting terminal and a receiving terminal are connected through a channel. In both the transmitting and receiving terminals, g is a generator of a group G<SB>q</SB>of order numbers q, a generator h which is different from g holds unitariness of the set G<SB>q</SB>. Further, in the transmitting terminal, a message m holds the unitariness of the G<SB>q</SB>and m=gs holds the unitariness of the set G<SB>q</SB>(s: unitariness of a set Z<SB>q</SB>, s: a seed of the message, Z<SB>q</SB>: an integer 0 to q-1). The transmitting terminal generates the unitariness of the set Z<SB>q</SB>by a random number r(r:r<SB>1</SB>, r<SB>2</SB>) and sends (Expression 1 including a formula) to the receiving terminal. The receiving terminal stores u, generates the unitariness of the set Z<SB>q</SB>by a random number x to calculate y=g<SP>x</SP>and z=h<SP>x</SP>, and sends (Expression 2 including a formula) to the transmitting terminal. The receiving terminal calculates m=cu<SP>-x</SP>to obtain the message. COPYRIGHT: (C)2005,JPO&NCIPI
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