对具有高代数免疫度布尔函数的新型代数攻击

代数免疫度是衡量布尔函数抵抗代数攻击的重要性能指标，具有低代数免疫度的布尔函数是不能抵抗代数攻击的．利用分拆布尔函数的方法证明了如下结论: (1)对于对称布尔函数，即使它们具有高代数免疫度，如果使用不当仍然不能抵抗新型代数攻击; (2)对于由旋转对称函数和低次布尔函数的直和构成的布尔函数即便具有高代数免疫度，如果使用不当，也会受到新型代数攻击．提出的代数攻击需要一段连续的密钥流．

Algebraic attack on symmetric Boolean functions with a high algebraic immunity

Algebraic immunity is an important index to measure the ability to resist algebraic attacks. If a Boolean function has a low algebraic immunity, then it can not resist the algebraic attack. This paper gives two conclusions on some Boolean functions with a high algebraic immunity, that is, 1) for most of symmetric Boolean functions with a high algebraic immunity, if they are used inappropriately, then the attacker still can launch an efficient algebraic attack; 2)our algebraic attack is still efficient for a more general class of Boolean functions with a high algebraic immunity, which consists of a rotation symmetric Boolean function and a Boolean function with a low degree. Our algebraic attack requires a segment of the consecutive bitstream.