针对正交频分复用无源光网络(orthogonal frequency division multiplexing passive optical network,OFDM-PON)系统中的数据传输安全问题,本文设计了一种基于多混沌系统及多层加密的数字序列加密方案,通过在OFDM信号生成的每个步骤都采用密钥集选择性对信号加密,可有效提升系统的加密空间进而增加系统的保密性。首先,将明文进行分组,利用Logistic混沌系统选取构建混沌序列集中的混沌序列对每组明文进行异或加密调制成16-QAM(quadrature amplitude modulation)信号；然后,对QAM信号分组,利用Logistic混沌系统对每组QAM信号进行判定是否进行星座图置乱加密；最后,对OFDM的子载波进行分组,利用Logistic系统对每组进行判定是否需要进行频域置乱加密。 搭建了仿真系统以进一步验证方案的可行性。 仿真实验结果表明,该加密方法极大地增大了密钥空间,达10⁵⁴⁰,为数据传输提供良好的保密性。

To significantly bolster the security of data transmission in an orthogonal frequency division multiplexing passive optical network (OFDM-PON) system,we propose a digital sequence encryption scheme based on multi-chaotic system with multi-layer encryption scheme.By constructing chaotic sequence set with different chaotic system and using them for the various processing of OFDM signals′ generation,the encrypted key space of OFDM-PON system can be improved,which can enhance the confidentiality of system.Firstly,the transmitted data namely plaintexts would be grouped, and then by using the Logistic chaotic system to select the chaotic sequency from the chaotic sequency set to further perform the XOR operations with each set of plaintexts.Consequently,the encrypted data is injected into the 16-QAM (quadrature amplitude modulation) module. Secondly,the Logistic chaotic system is used to select the grouped-QAM signals and determine whether to encrypt the selected signals.Then,the subcarriers of the OFDM signals are grouped,and then are selected by the Logistic chaotic system to realize the encrypted operation.At last,the simulation experiment system is established to provide further validation of the feasibility of our scheme.And,the corresponding results show that,our scheme can present the good confidentiality,and 10⁵⁴⁰key spaces can be achieved.

国家自然科学基金(61906055)、 浙江省自然科学基金(LY20F050004)和江苏省新型光纤技术与通信网络工程研究中心开放研究课题(SDGC2120)资助项目