| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem of key escrow performance in an information (key) sharing method base on ID information. SOLUTION: A group G<SB>1</SB>and a group G<SB>2</SB>are connected by one-way isomorphismψ: G<SB>1</SB>→G<SB>2</SB>. Assume that s denotes a maser secret key for a TA device, an orign g1E* G<SB>1</SB>, an origin g2E* G<SB>2</SB>, rA denotes a random number generated by a communication device A, and rB denotes a random number generated by a communication device B. Then (1) the TA device calculates P=[s]g<SB>1</SB>E*G<SB>1</SB>, S<SB>A</SB>=[s]ID<SB>A</SB>E*G<SB>2</SB>, and S<SB>B</SB>=[s]ID<SB>B</SB>E*G<SB>2</SB>. P is disclosed, S<SB>A</SB>is transmitted to the communication device A, S<SB>B</SB>is transmitted to the communication device B. (2) The communication device A calculates W<SB>A</SB>=S<SB>A</SB>+[r<SB>A</SB>]g<SB>2</SB>E*G<SB>2</SB>, and transmits the calculated result to the communication device B. The communication device B calculates W<SB>B</SB>=S<SB>B</SB>+[r<SB>B</SB>]g<SB>2</SB>E*G<SB>2</SB>, and transmits the calculated result to the communication device B. (3) The communication device A calculates K<SB>A</SB>=(e(W<SB>B</SB>, g<SB>1</SB>)/e(ID<SB>B</SB>, P))<SP>rA</SP>, and the communication device B calculates K<SB>B</SB>=(e(W<SB>A</SB>, g<SB>1</SB>)/e(ID<SB>A</SB>, P))<SP>rB</SP>. E* means "belong to", or "belongs to". COPYRIGHT: (C)2009,JPO&INPIT
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