• 정보보호학회논문지
• /
• 제17권3호
• /
• pp.109-116
• /
• 2007

본 논문에서는 Self-Shrinking 생성기의 변형 구조 SSG-XOR에 대해 guess-and-determine공격을 적용하여 실제 안전성을 분석하고 이에 대한 시뮬레이션 결과를 소개한다. SSG-XOR은 Self-Shrinking 생성기에 비해 더 좋은 암호학적 성질을 가지는 것으로 소개되었으나 본 논문의 분석 결과, guess-and-determine공격 관점에서 Self-Shrinking 생성기에 비해 안전성이 많이 떨어지는 것을 확인할 수 있다.

• Journal of Information Processing Systems
• /
• 제7권1호
• /
• pp.151-158
• /
• 2011

Bivium is a simplified version of Trivium, a hardware profile finalist of the eSTREAM project. Bivium has an internal state size of 177 bits and a key length of 80 bits. In this paper, a guess and determine attack on this cipher is introduced. In the proposed method, the best linear approximations for the updating functions are first defined. Then by using these calculated approximations, a system of linear equations is built. By guessing 30 bits of internal state, the system is solved and all the other 147 remaining bits are determined. The complexity of the attack is O ($2^{30}$), which is an improvement to the previous guess and determine attack with a complexity of order O($2^{52.3}$).