Image encryption and decryption method based on probability interval division and dynamic probability events

Abstract

The invention provides an image encryption and decryption method based on probability interval division and dynamic probability events. The method comprises steps of during encryption, firstly mapping secret key parameters and SHA-1 values of to-be-encrypted images to different probability encryption sections; carrying out random screening on to-be-encrypted pixels based on the secret key parameters and the SHA-1 values; and executing and writing different probability encryption events into corresponding pixel positions according to the probability sections where the probability encryption events fall. In order to improve safety, an SHA-1 value remapping process is added for dividing the probability sections, screening the to-be-encrypted pixels and carrying out stochastic disturbance on encryption; and by adding an overall situation encryption process related to SHA-1 update values and user secret keys, performance of an image encryption algorithm is enhanced. The method also comprises steps of during decryption, firstly recovering encrypted parameters; then finishing overall decryption; and at last executing inverse decryption operation on randomly screened pixels. Compared with the prior art, different pixels and secret keys correspond to different encryption processes, so the method is highly safe.

Description

technical field [0001] The invention belongs to the cross-research field of information security and digital image signal processing, relates to a digital image encryption and decryption method, in particular to an image encryption and decryption method based on probability interval division and dynamic probability events. Background technique [0002] In recent years, with the development of computer and network technology, more and more images are transmitted on the network, which brings a series of security risks while providing convenience to users. Improper use or malicious tampering of images not only involves personal privacy, but also has a serious negative impact on society. The core technology to ensure the security of digital images is digital image encryption. [0003] Since Robert Matthews, 1989 (Robert Matthews. Onthe derivation of a "chaotic" encryption algorithm [J].Cryption, 1989, 13 (1): 29-42) put forward the idea of ​​chaotic encryption, the image encryp...

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Problems solved by technology

Although the literature (BenyaminNorouzi et al., 2014 and Li Yuanyuan et al., 2013) strengthened the connection between the key and the plaintext, the plaintext can only exert influence on the parameters of the image encryption link, but cannot specifically change the encryption link experienced. There are still great security risks in the actual use process

[0007] Among the applied invention patents (Shao Liping, Guo Yi, Yang Lu. Image encryption and decryption method based on improved Joseph traversal and generalized Henon mapping [P]. China, State Intellectual Property Office of the People's Republic of China, Invention Patent, 201410145368.7) , we use the SHA-1 value of the image to be encrypted and the encryption parameters selected by the user as the key to drive the generalized Henon map to the starting position, report interval and report direction of the improved Joseph traversal map for site replacement Random perturbation is carried out, so that different encrypted images and encryption parameters correspond to different site replacement processes; this method enhances the coupling of each encryption link, and different images to be encrypted start different encryption processes, so it can effectively resist Selective plaintext attack, the proposed method strengthens the association between the key and the plaintext, but the plaintext can only exert influence on the parameters of the image encryption link, but cannot specifically change the encryption link experienced

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