Multi chaos-based image encryption and lossy compression

The purpose of this paper was to increase the transmission speed and give more secure communication when the image is transmitted through network. In some application scenarios, a sender needs to transmit some data to a receiver and hopes to keep the information confidential to a network operator who provides the channel resource for the transmission. That means the sender should encrypt the original data and the network provider may tend to compress the encrypted data without any knowledge of the cryptographic key and the original data. At receiver side, decryption functions will be used to reconstruct the original image. Encryption gives secure communication through network and compression reduce the size of image and increase the transmission speed. The encryption step proposed in this project is chaos based encryption. The two basic properties of chaotic systems are the sensitivity to initial conditions and mixing property. Two chaotic maps, Quadratic and tent maps are used to produce the chaotic sequence and used to control the encryption process. The bitwise XOR operation is used to create encrypted image. After encryption process over, the sender sends encrypted image to network operator. The network operator compressed the image by haar wavelet transform which give high compression ratio, so that storage capacity required will be smaller. In receiver side then decompressed image is decrypted by same symmetric key which is used in sender side. The decrypted image having some noise due to encryption, compression and decryption process, so that noise is removed in decrypted image by image enhancement technique for improve the PSNR value.