Research And Implementation Of Commutative Encryption Watermarking Algorithm Based On Homomorphism

Encryption and watermarking are the two main security protection technologies for digital multimedia today,and their effects and functions are different.As an active security protection method,encryption prevents information leakage by converting original plaintext information into unreadable ciphertext.It can protect multimedia information from confidentiality during transmission and storage.But after decryption by legitimate users,they can arbitrarily copy,spread and modify.Digital copyright protection and integrity authentication can be accomplished through watermarking technology,but watermarking can not guarantee the confidentiality of protected multimedia.Obviously,only encryption or watermarking is not adequate for comprehensive protection of digital multimedia.At the same time,the simple superposition of encryption and watermarking can lead to security,efficiency and other issues.Therefore,in recent years,some research scholars have begun to pay attention to the combination of encryption and watermarking technology.The Commutative Encryption Watermarking(CEW)algorithm is a combination of cryptography and digital watermarking technology,which is used for multimedia information security and copyright protection.At present,the Commutative Encryption Watermarking technology is a hot research topic in the field of information security.The main work of this paper includes the following aspects:(1)Based on the Zu Chongzhi(ZUC)sequence cipher and quantization index modulation digital watermarking algorithm,an Commutative Encryption Watermarking algorithm is designed.In order to ensure the security of the carrier data,Adopt ZUC sequence cipher and modulo operation to perform modulo encryption on information,combined with quantization index modulation digital watermarking algorithm,design an CEW algorithm.The experimental results show that the algorithm realizes the sequential exchange of encryption operation and digital watermarking algorithm,ensuring the security of multimedia data in the distribution management process,and at the same time,the comprehensive performance of the watermarking algorithm is also improved.(2)Based on the multiplicative homomorphism of El Gamal cipher system and Patchwork digital watermarking algorithm,an exchange encryption watermarking algorithm is researched and designed.Using the multiplicative homomorphic feature of the El Gamal cryptographic algorithm,combined with the Patchwork watermarking algorithm,the plaintext watermarking algorithm is homomorphically mapped to the ciphertext domain to realize the embedding of the ciphertext watermark and the plaintext watermark.The problem of mutual influence between encryption and digital watermark is solved,and the watermark can be extracted directly in the ciphertext state and the watermark can also be extracted in the plaintext after decryption.The experimental results further show the correctness and safety of the algorithm.(3)Based on the elliptic curve cryptosystem and the watermarking algorithm of the histogram shift of the difference domain,a CEW algorithm based on the elliptic curve cryptography is proposed.The algorithm uses the homomorphic characteristics of the elliptic curve cryptographic algorithm,combined with the watermark algorithm of the difference domain histogram translation,by calculating the prediction error value to determine the embeddable watermark information,and extracts the watermark according to the position of the embeddable watermark information and the prediction error value,and restore the carrier image according to the least significant bit of the pixel.Experimental results show that the algorithm can embed a watermark in the ciphertext domain as well as in the plaintext domain.Encryption and watermark operations can be exchanged,and it has a high embedding rate and reduces image distortion.