| 摘要 |
PROBLEM TO BE SOLVED: To provide a security apparatus for improving the security against an attack from a third party while keeping the convenience in a key delivery system and a public key encryption system. SOLUTION: The security apparatus 10 transmits a multivariable common polynomial a(x<SB>1</SB>, x<SB>2</SB>, ..., x<SB>n</SB>) to the security apparatus 20, and further transmits a multivariable polynomial b(x<SB>1</SB>, x<SB>2</SB>, ..., x<SB>n</SB>)=a(x<SB>1</SB>+s<SB>1</SB>, x<SB>2</SB>+s<SB>2</SB>, ..., x<SB>n</SB>+s<SB>n</SB>)<SP>s0</SP>modI calculated by arithmetic means 2a, 2b to the security apparatus 20 by using integer sets s(s<SB>0</SB>, s<SB>1</SB>, s<SB>2</SB>, ..., s<SB>n</SB>) set by the security apparatus 10. On the other hand, the security apparatus 20 transmits a multivariable common polynomial c(x<SB>1</SB>, x<SB>2</SB>, ..., x<SB>n</SB>)=a(x<SB>1</SB>+t<SB>1</SB>, x<SB>2</SB>+t<SB>2</SB>, ..., x<SB>n</SB>+t<SB>n</SB>)<SP>t0</SP>modI calculated by arithmetic means 3a, 3b to the security apparatus 10 by using integer sets t(t<SB>0</SB>, t<SB>1</SB>, t<SB>2</SB>, ..., t<SB>n</SB>) set by the security apparatus 20. The arithmetic means 2a, 2b calculate c(x<SB>1</SB>+s<SB>1</SB>, x<SB>2</SB>+s<SB>2</SB>, ..., x<SB>n</SB>+s<SB>n</SB>)<SP>s0</SP>modI and the arithmetic means 3a, 3b calculate b(x<SB>1</SB>+t<SB>1</SB>, x<SB>2</SB>+t<SB>2</SB>, ..., x<SB>n</SB>+t<SB>n</SB>)<SP>t0</SP>modI as common keys. COPYRIGHT: (C)2004,JPO
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