Abstract: According to the flaws in the design of the stream cipher part of SCB (senior cross breed) algorithm, the initial key could be recovered with the computational complexity of O(2⁴⁴) if the key stream of the stream cipher was known. To acquire the keystream of the stream cipher, a differential fault attack was proposed by using word oriented fault model for one bit random fault. When 640 faults were induced, the success rate could achieve 99.4%. The computational complexity to recover the 256 bit key was O(2⁴⁴).

Key words: cryptanalysis, block cipher, stream cipher, hybrid symmetric cipher, differential fault attack

摘要： 针对SCB (senior cross breed)算法序列部分设计的安全问题, 在已知序列部分生成的密钥流的情况下,用 O(2⁴⁴)的计算复杂度恢复算法的种子密钥。为得到序列部分攻击所需要的密钥流, 基于单比特随机故障模型, 对SCB算法分组部分进行了差分故障攻击, 当引入640次故障时, 攻击算法成功率可以达到99.4%。恢复算法256 bit种子密钥需要的计算复杂度为O(2⁴⁴)。

关键词: 密码分析, 分组密码, 序列密码, 混合对称密码, 差分故障攻击