Abstract: During the implementation of a cryptographic processor, considerable resources are wasted because of the isomerization of the S box and the Non-linear Boolean Function(NBF) in its symmetric cipher.A reconfigurable circuit structure of an AES-like S box and NBF is proposed to address this problem.The original Non-linear Boolean Function Module (NBFM) in S-box problems is analyzed.The 4-4, 6-4 S-box circuits provide better adaptation but cannot support 8-8 S-box circuits.Based on the tower domain decomposition theory, this paper demonstrates that AES-like S box circuits differ only in terms of the conversion matrix before and after the decomposition.Using the mixed basis method, an AES-like S box circuit is decomposed into various operation modules on GF(16), and the bit level expression of these modules is derived.When adapting these modules specifically, the gate level implementation, NBFM adaptation implementation, or an appropriate improvement of the NBFM implementation are adopted.Finally, a reconfigurable circuit similar to the AES-like S box and NBF is realized.Experimental results show that a complete AES-like S box circuit can be realized by this method using four NBFMs and 22.7% of the S box circuit area without affecting the function of the original NBF.

Key words: AES-like s box, Non-linear Boolean Function(NBF), Non-linear Boolean Function Module(NBFM), finite field isomorphism, cryptographic

摘要： 为解决对称密码中s盒和非线性布尔函数（NBF）在实现密码专用处理器时采用异构化设计导致的资源浪费问题，提出一种类AESs盒和NBF的可重构电路结构方法。分析s盒问题中的原有非线性布尔函数模块（NBFM），4-4、6-4的s盒电路能够提供更好的适配性，但不能很好地支持8-8的s盒电路。基于塔域分解理论，论证不同的类AESs盒电路差异在于输入前后的转换矩阵。采用混合基的方法将类AESs盒电路分解成GF （16）上的各个运算模块，并推导出模块比特级别表达式，在具体适配运算模块时采取门级实现、NBFM适配实现或对NBFM进行改进3种方案，实现类AESs盒和NBF的可重构电路。实验结果表明，该方法在不影响原有NBF功能的基础上，利用4个NBFM与22.7%的s盒电路面积即可实现一个完整的类AESs盒电路。

关键词: 类AES s盒, 非线性布尔函数, 非线性布尔函数模块, 有限域同构, 密码

CLC Number: 

• TN918.1