Research On PNG Image Encryption Algorithm Based On Content-associated Key

In today's era,with the spread of the Internet and the development of multimedia,the image has been widely used,the demand for image transmission is also higher and higher,the security of image in transmission is playing an increasingly important role,the research of image encryption is also more and more critical.PNG is an important image format.PNG image is widely used in network,software and mobile phone,so it is of great significance to study the encryption of PNG image.In today's huge amount of data,the traditional encryption technology symmetric encryption and asymmetric encryption,they have certain defects,may not encrypt the key attributes of the file,key ciphertext correlation is not high,in the process of computer technology development,their security risks are also growing.At the same time,their encryption depends on the complexity of computation,and there is a contradiction between encryption strength and time cost.Content associated key encryption technology is a kind of encryption technology which has a close relationship between key and ciphertext.The key information of the file is extracted as the key,and the remaining part can be filled with irrelevant data as ciphertext.The encryption mode seems to be fixed.However,the encrypted keys of different files are independent individuals with their own characteristics,which can not be found through the comparative analysis of different keys To the rule,it belongs to a new file encryption algorithm with high security.The PNG image encryption algorithm based on content associated key is divided into key information part and non key information part by analyzing the format of PNG image file.The key information of image is randomly extracted by random number generator,and the extracted data are combined into key block,and then the irrelevant data generated by random number generator is used to extract the position of data information The security of encryption is greatly improved by using Logistic chaotic mapping technology to encrypt the backfilled data.The Logistic chaotic encryption key block is combined with the extracted data key block to form a complete PNG image encryption key,and the data encrypted by Logistic chaotic mapping technology is the final ciphertext.The research of PNG image encryption algorithm can alleviate the security defects of traditional encryption technology to a certain extent.The security and time cost of image data encrypted by PNG image encryption algorithm based on content associated key are tested and studied.The security and feasibility of PNG image encryption algorithm based on content associated key is proved.