Research On Reversible Data Hiding Algorithm Of Encrypted Image Based On Local Pixel Prediction And Difference Value

With the rapid development of computer technology and 5G technology,the network transmission capability has been rapidly improved,which provides convenience for the dissemination,processing,copying,and utilization of information,but at the same time,the interception of network transmission information has also become simple,and the stored information will be Attack,information security is threatened.Encryption and information hiding are two effective means of information protection.The former converts secret information into unreadable ciphertext,and only authorized users can decrypt it correctly,while the latter hides the secret information in the carrier and makes it invisible to the outside world,thus achieving privacy.Transmission,copyright protection.Reversible information hiding can not only extract secret information,but also restore the original image.It plays an important role in sensitive fields such as military,medical,and judicial identification.The combination of reversible information hiding in the ciphertext domain can not only protect the original information from being leaked,but also realize the management of the ciphertext data.It can not only realize the lossless recovery of the original carrier,but also accurately extract the secret information,and has a wide range of applications in the field of information security.This thesis is mainly based on the research of reversible information hiding algorithms for encrypted images.The main research results are as follows:1.A reversible data hiding algorithm for encrypted images based on local pixel prediction is proposed.The original image is divided into blocks,a random number is generated according to the key and the pixels in the block are summed and modulo,and then the key is used to scramble the block to obtain an encrypted image.Three pixels adjacent to the pixel to be predicted are used to construct a linear prediction model,three adjacent pixels are used as sample pixels for solving parameters,and the adjacent pixels are used to establish equations.The equations are solved to obtain prediction model parameters and determine the prediction model.The prediction model is used to predict the encrypted image,the prediction error is calculated,the histogram of the prediction error is calculated,and the reversible information hiding of the encrypted image is realized by the histogram translation method.The experimental results show that applying the prediction model in this thesis to predict with fewer prediction pixels improves the prediction accuracy and reduces the distortion of the encrypted image after direct decryption.2.A reversible data hiding algorithm for encrypted images based on difference is proposed.The original image is divided into blocks,and the fixed position pixels in the block are used as reference pixels to calculate the difference between all non-reference pixels and reference pixels in the block,and the difference is modulus-calculated to obtain the difference modulus pixel.Use the key to generate a random number to XOR the reference pixels and scramble the position of the difference modulus pixels in the image.The difference image modular pixel and the reference pixel in the block are added to obtain an encrypted image.The difference between the pixels in the block and the reference pixel is calculated,and the difference is calculated to obtain a difference histogram,and the reversible information hiding is realized by shifting the difference histogram.Experimental results show that the encryption method in this thesis has good security,and the quality of the directly decrypted image is high.3.A reversible data hiding algorithm for encrypted images based on block difference compression is proposed.For the original image block,traverse the pixels in the block in the "inverse S" way to obtain the pixel sequence,keep the last pixel unchanged,and calculate the difference between adjacent pixels.Random numbers are generated by the key to perform XOR operation on the last pixel in the block,and scrambling the position of the difference pixel.The pixels in the block are traversed in reverse order,and the encrypted image is obtained through addition and modulo operations.Perform a difference operation on the encrypted image block,mark the pixel position where the difference within the block is greater than 127,transform the pixel with the difference greater than 127 into a pixel with less than 127,and then calculate the maximum value of the difference within the block to obtain the required storage space To get compressed space.Embed data into the vacated space to achieve reversible data embedding.Experimental results show that this thesis proposes a block difference compression encrypted image reversible information hiding algorithm,which makes good use of the characteristics of encryption retention and improves the embedded capacity of information.