Concerning the problem that the transmission and storage of massive redundant image data in Internet of Things （IoT） lead to high resource consumption and potential privacy leakage， a Deep Compressive Sensing （DCS） network for IoT images and its chaotic encryption protection method were proposed. Firstly， an improved DCS network was proposed to achieve high-quality image compression and reconstruction. In this network， residual blocks in conventional deep reconstruction network were modified using a channel attention mechanism， and a parallel fusion design integrating multi-scale branches and a fusion module was adopted， thereby improving the reconstruction performance of traditional deep reconstruction network based on residual stacking in convolutional layers. Secondly， a multi-cavity chaotic system was proposed to realize spherical cavity expansion in the X， Y， or Z direction — either in one direction or both directions — through spherical coordinate transformation and two sets of parity-controlled step functions. This system has chaotic properties and randomness， making it suitable for image encryption. Finally， based on the proposed DCS network and the multi-cavity chaotic system， encryption and decryption for DCS measured images was designed using chaotic index scrambling and diffusion， and detailed security analysis was conducted， thereby guaranteeing the security of image transmission. Experimental results show that compared with the classical DCS method CSNet+， the proposed network achieves an average increase of 0.606 dB （0.25-1.42 dB） in Peak Signal-to-Noise Ratio （PSNR） and an average 1.11 percentage point （0.69-2.17 percentage point） improvement in Structural Similarity Index Measure （SSIM）.

In order to strengthen anti-interference and anti-interception performance of chaotic system in communication link， and improve complexity of chaotic system behavior， based on typical Chua’s circuit and step function， a new type of grid multi-scroll chaotic system family with controllable quantity was constructed. First， two sets of step functions were used as nonlinear controllers of the system， which respectively controlled the numbers of the odd and even columns and the arranging rows for the grid multi-scroll chaotic attractors， and kept the scrolls and bonds in chaotic attractors being interleaved with each other. As a result， the arbitrary number of odd and even columns for the grid multi-scroll were realized. Then， the dynamic properties of system such as equilibrium point， Lyapunov exponent and attractor were theoretically analyzed and numerically simulated. Finally， the hardware experiment results of up to 4 rows and 12 columns of grid multi-scroll were given by Field Programmable Gate Array （FPGA）. Hardware and software experimental results are in full agreement with theoretical analysis results， which furtherly proves the proposed system’s physical realizability.

S-box is one of the key components in block cipher algorithm， and its confounding and scrambling effect determines security strength of the whole cipher. In order to ensure better cryptographic performance of S-boxes generated based on chaotic systems， a dynamic S-box design scheme based on anti-degradation chaotic system was proposed. Firstly， Chebyshev chaotic map was disturbed by Lorenz chaotic map. Then， two initial S-boxes were generated by interception method and interval partition method. Finally， the final S-box was obtained by using index sort perturbation method. The chaotic sequences generated by anti-degenerate chaotic system do not have phenomenon of short cycle， and have characteristics of ergodic property and unpredictability. When applying these sequences to the design of S-box， the safety performance of S-box can be greatly improved， and the hidden danger of chaos generation source can be eliminated. Moreover， dynamic S-boxes can be generated in batches by adjusting system parameters. The safety performance of S-box， including nonlinearity， difference uniformity， strict avalanche criterion， output bits independence criterion and bijective characteristics， was tested and compared. Experimental results show that the S-box generated by the proposed scheme has better cryptographic performance and can be used in design of block cipher.