| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an information sharing technique capable of securing the safety even if a master secret key z, and a short-term secrete key y<SB POS="POST">A</SB>of an information sharing device U<SB POS="POST">A</SB>are leaked. <P>SOLUTION: A shared value calculation unit 22 of an information sharing device U<SB POS="POST">A</SB>performs a process for calculating shared value σ<SB POS="POST">i</SB>=e(Z<SP POS="POST">ci,</SP><SP POS="POST">1sA+ci,</SP><SP POS="POST">2yA</SP>, Q<SB POS="POST">B</SB><SP POS="POST">ci,</SP><SP POS="POST">3</SP>Y<SB POS="POST">B</SB><SP POS="POST">ci,</SP><SP POS="POST">4</SP>) for each of i=1,..., n, and performs a process for calculating a shared value σ'<SB POS="POST">j</SB>=Y<SB POS="POST">B</SB><SP POS="POST">c'j,</SP><SP POS="POST">1sA+c'</SP><SP POS="POST">j,</SP><SP POS="POST">2yA</SP>for each of j=1,..., n'. A shared value calculation unit 32 of an information sharing device U<SB POS="POST">B</SB>performs a process for calculating a shared value σ<SB POS="POST">i</SB>=e(P<SB POS="POST">A</SB><SP POS="POST">ci,</SP><SP POS="POST">1</SP>Y<SB POS="POST">A</SB><SP POS="POST">ci,</SP><SP POS="POST">2</SP>,D<SB POS="POST">B</SB><SP POS="POST">ci,</SP><SP POS="POST">3</SP>Z<SP POS="POST">ci,</SP><SP POS="POST">4yB</SP>) for each of i=1,..., n, and performs a process for calculating a shared value σ'<SB POS="POST">j</SB>=e(P<SB POS="POST">A</SB><SP POS="POST">c'j,</SP><SP POS="POST">1</SP>, Y<SB POS="POST">A</SB><SP POS="POST">c'j,</SP><SP POS="POST">2</SP>)<SP POS="POST">yB</SP>for each of j=1,..., n'. <P>COPYRIGHT: (C)2012,JPO&INPIT |
