| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2003: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2002: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
Differential attack, Linear attack Higher order differential attack, Interpolation attack and Linear sum interpolation attack are typical attacks for common-key block ciphers. The strength of a block cipher is measured by its differential probability, linear probability, algebraic degrees, and {number of terms and degree} of interpolation polynomial.
In this research, we have developed a block cipher strength evaluation tool which gives the following measure for S-boxes, whose input bit size is less than 16, as C++ functions.
・Differential attack maximal differential probability, best input/output differential and differential probability distribution
・Linear attack : maximal linear probability, best input/output linear mask and linear probability distribution for S-boxes
・Higher order differential attack/Interpolation attack/Linear sum attack : Boolean expression, Interpolation polynomials on GF(2^m) with any modulus polynomial, and characteristics of interpolation polynomials.
These functions are open to public in our home page as free software libraries. Using the tool we also have published papers which discuss the strength / new attack method for MISTY1, KASUMI, Camellia, IDEA, RISM etc.
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