The invention relates to a safety light
access method based on two-stage spherical
constellation masking, which comprises the following steps: taking a Chua's circuit model as a first
chaotic model for generating a first-stage masking factor based on
constellation rotation; taking the Logistic model as a second
chaotic model for generating a secondary masking factor based on
constellation scaling;applying the two levels of masking factors to three-dimensional CAP
encryption modulation; three-dimensional CAP decryption
demodulation. According to the method disclosed in the invention, the two
chaotic models are combined to respectively realize multi-chaotic combined
encryption on constellation rotation and amplitude transformation, and therefore the safety performance of the optical accesssystem can be more effectively improved. Meanwhile, constellation masking is three-dimensional constellation
encryption in a three-dimensional space; compared with a two-dimensional constellation, three-dimensional constellation is advantageous in that dimension improvement enables encryption transformation to be more flexible, the safety performance of a
physical layer after constellation encryption is greatly improved, the
Euclidean distance between three-dimensional constellation points is larger, and the
bit error rate performance of the
system is improved.