一种带有时序参数的分组密码

通过将系统时间和数据组号混合到轮密钥之中，可以有效地防止一些对分组密码算法的攻击．文中探讨了这类实用的密码算法方案的一般模式．由于变更部分轮密钥通常比若干轮变换快很多，这类方案会有明显的效率优势．在安全方面，由于加密时所有明文组几乎都各自使用了不同的轮密钥，而绝大数攻击方法需要一定数量相同密钥加密的明密文对，从而使这些攻击方法不能奏效．这也许会导致这类带有时间组号参数的分组算法在减少迭代轮情况下仍然是安全的．做为例子，给出了一个在安全和效率方面均有良好性能的密码算法TCR6．

BLOCK CIPHERS WITH TC PARAMETERS

Certain kind of attacks on some block ciphers may be efficiently resisted by mixing the round keys with a group of frequently changed numbers computed from system time and the counter of data blocks.The general form of such practical schemes has been discussed.Because the changing of certain part of round keys is often much faster than the operations of certain rounds of encryption (or decryption),the efficiencies of this kind of block cipher schemes are quite obvious.In security,as nearly every plaintext data block is encrypted with different keys,and as most attacking techniques have high demands of plaintext/ciphertext pairs,it is difficult for them to work in such a cipher scheme.This may result that a block cipher with time and counter parameters is secure even with cases that the number of round is largely reduced.As an important example of the entire solution,we introduce a cipher scheme TCR6 which has some satisfactory features in both security and efficiency.