個の弱鍵の存在を示した.しかしながら,我々が乗算部の解析を行った結果,線形確率が1となる拡大鍵"2","2^<15>","2^<15>+1","2^<16>-1"が存在することを発見することを発見した.本稿では,この結果を用いて,IDEAの線形確率が1となる弱鍵の再評価を行うことにより,弱鍵の総数が従来の2倍に増えたことを示す." />

Presentation 2003/9/12
A Study on Weak Keys of IDEA
Kazuya HATAKEYAMA, Yasuo HATANO, Tsoshinobu KANEKO,
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Abstract(in English) Deamen et al. showed that IDEA has 2^<23> weak keys that holds with linear probability 1. To find the weak keys, they used the sub-keys equal to 0 or 1, which have linear probability 1 on the multiplication of IDEA on module 2^<16>+1. On the multiplication, however, we found the sub-keys, 2.3^<15>, 2^<15>+1, and 2^<16>-1 also hold with linear probability 1. We re-evaluate the weak keys of IDEA by using these sub-keys and show that the total number of weak keys increases to twice compared the weak keys shown by Deamen et al.
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Keyword(in English) Block Cipher / IDEA / Weak Keys / Linear Probability
Paper # ISEC2003-57
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Committee ISEC
Conference Date 2003/9/12(1days)
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Language JPN
Title (in Japanese) (See Japanese page)
Sub Title (in Japanese) (See Japanese page)
Title (in English) A Study on Weak Keys of IDEA
Sub Title (in English)
Keyword(1) Block Cipher
Keyword(2) IDEA
Keyword(3) Weak Keys
Keyword(4) Linear Probability
1st Author's Name Kazuya HATAKEYAMA
1st Author's Affiliation Department of Electrical Engineering, Faculty of Science and Technology, Technology, Tokyo University of Science()
2nd Author's Name Yasuo HATANO
2nd Author's Affiliation Department of Electrical Engineering, Faculty of Science and Technology, Technology, Tokyo University of Science
3rd Author's Name Tsoshinobu KANEKO
3rd Author's Affiliation Department of Electrical Engineering, Faculty of Science and Technology, Technology, Tokyo University of Science
Date 2003/9/12
Paper # ISEC2003-57
Volume (vol) vol.103
Number (no) 315
Page pp.pp.-
#Pages 5
Date of Issue