时空混沌自同步流密码系统的选择密文攻击

Chosen-ciphertext Attack for Chaotic Self-synchronizing Stream Cryptosystem

密码系统是否保密在于它能否抵御所有已知的攻击方法,如果利用所有的攻击方法获取系统密钥所花的代价都不比穷尽搜索攻击方法所花的代价低,而实际的计算资源和可用来计算的时间又不可能承受穷索密钥的任务,那么这个密码系统是实际保密的.我们用分类中最强的选择密文攻击对时空混沌自同步流密码系统进行了分析,结果表明,即使在最弱密钥条件下,选择系统抵抗力最弱的常数密文驱动攻击所花的计算代价仍然远远高于穷尽搜索攻击的代价,因此,本时空混沌密码系统是一个具有实际保密性的密码系统.

The security of the cryptosystem is based on against all known attacks.A cryptosystem is called the practical security if the cost of obtaining secret keys used by any other attacks is larger than that of obtaining secret keys used by the searching attack(brute force attack),on the other hand,the practical calculative sources and calculative time can not bear this searching attack.It is found that the cost for our cryptosystem analyzed by the chosen-ciphertext attack with selected weakest secret keys and selected weakest constant ciphertext is still larger than that by the searching attack.Hence,the high practical security of chaotic self-synchronizing stream cryptosystem is demonstrated.