| With the rapid development of communication technology,computers and the Internet,information is stored and transmitted at all times,facing threats such as eavesdropping,interference,tampering and destruction,all of which have led to increased attention to the study of security technology.In recent years,some of the traditional encryption systems have been threatened by the rise of quantum computers.Chaotic systems have been used by many scholars to study new cryptographic techniques due to their strong sensitivity to initial sensitivity and their ability to generate a large number of non-periodic noise-like signals.In this paper,based on the current status of research on chaotic encryption algorithms,the following algorithms are proposed.(1)This thesis proposes a five-dimensional hyperchaotic coupled synchronization-based encryption technique for OFDM systems.The scheme uses a new five-dimensional hyperchaotic coupled synchronization system to encrypt three of the dimensions for the heteroskedastic operation of the bit stream and the offset mapping of the in-phase and orthogonal components of the constellation points,respectively.(2)A chaotic encryption technique using DNA coding and a fivedimensional hyperchaotic coupled synchronous system is proposed.The plaintext is then divided into small chunks and each chunk is encrypted using a chaotic sequence generated by a five-dimensional super-coupled chaotic synchronous system with randomly selected DNA encoding and operation rules.(3)A visual encryption technique based on a five-dimensional hyperchaotic coupled synchronous system and DWT is proposed.Firstly,a new five-dimensional hyper-chaotic coupled synchronous system is proposed.The encryption uses the MD5 hash algorithm to calculate the digest value of the plaintext as the initial key of the chaotic system,then the five-dimensional chaotic sequence generated by the chaotic system is used to perform Arnold random disruption,cyclic shift diffusion and chaotic sequence disruption to complete the encryption operation,and then the bit plane is extracted from the ciphertext.The bit planes are then embedded in the HL,LH and HH planes of the R,G and B channels of the carrier image after DWT transformation,and finally the carrier image is restored by IDWT.The proposed algorithms are compared with other encryption algorithms,and the security performance of the proposed encryption algorithms is good enough to resist statistical attacks,differential attacks and exhaustive attacks. |
