Encryption-Compression Method of Images

In digital signal processing, the general problem of image compression involves encoding using fewer bits than the original representation. Compression can be either lossy or lossless. Image encryption is hiding image from unauthorized access with the help of secret key. Even though Compression-then-Encryption (CTE) paradigm meets the requirements in many secure transmission scenarios, the order of applying the compression and encryption needs to be reversed in situations without compromising the compression performance. In this paper we analyze various techniques emerged for Encryption then Compression process for image data security.

INNOVATIONS IN COMPUTATIONAL AND COMPUTER TECHNIQUES: ICACCT-2021

This paper presents a survey on image encryption and compression techniques. The main aim of using encryption and compression together is to reduce the size; to ensure a quality during reconstruction; to reduce bandwidth requirement, to increase the speed of data communication over a network; to reduce the computational time, and to ensure its safety. To carry out the Image compression and encryption together three different ways are there. The three existing combinations are as encryption technique followed by compression, in this method compression ratio is more, but there are some security issues as compared with next. The next combination is a compression technique followed by encryption technique, in this method, researchers focus more on security of the image rather than to compress the size of the image. The last combination is joint encryption and compression strategies in this strategy encryption and compression happens at the same time either to some extent or as compressive detecting. With low computational time it gives a decent security. The compression procedure utilized in every one of the blends can be lossless, lossy, or mix of both.

Proceedings of SPIE, 2005

Advances in network communications have necessitated secure local-storage and transmission of multimedia content. In particular, military networks need to securely store sensitive imagery which at a later stage may be transmitted over bandwidth-constrained wireless networks. This work investigates compression efficiency of JPEG and JPEG 2000 standards for encrypted images. An encryption technique proposed by Kuo et al. in [4] is employed. The technique scrambles the phase spectrum of an image by addition of the phase of an all-pass pre-filter. The post-filter inverts the encryption process, provided the correct pseudo-random filter coefficients are available at the receiver. Additional benefits of pre/post-filter encryption include the prevention of blocking effects and better robustness to channel noise [4]. Since both JPEG and JPEG 2000 exploit spatial and perceptual redundancies for compression, pre/post-filtered (encrypted) images are susceptible to compression inefficiencies. The PSNR difference between the unencrypted and pre/post-filtered images after decompression is determined for various compression rates. Compression efficiency decreases with an increase in compression rate. For JPEG and JPEG 2000 compression rates between 0.5 to 2.5 bpp, the difference in PSNR is negligible. Partial encryption is proposed wherein a subset of image phase coefficients are scrambled. Due to the phase sensitivity of images, even partial scrambling of the phase information results in unintelligible data. The effect of compression on partially encrypted images is observed for various bit-rates. When 25% of image phase coefficients are scrambled, the JPEG and JPEG 2000 compression performance of encrypted images is almost similar to that of unencrypted images for compression rates in the 0.5 to 3.5 bpp range.

2010

In this paper, a novel approach is designed for transmitting images securely using a technique called Gödelization followed by the public key encryption. The image which is to be transmitted is transformed into a sequence called Gödel Number Sequence (GNS) using a new technique called Gödelization. This is compressed using Alphabetic coding AC) and encrypted by an encryption method. This encryption string is transmitted and reconstructed at the decoding end by using the reverse process.

Compression is important because it helps us to reduce the consumption of expensive resources, such as disk space and cost for using bandwidth. Use of the right compression method and encryption technique yield more compact and secure data that are eligible to transfer over public channel. We introduce an optimal approach to compress and then encrypt images. The proposed method is used to increase the compression ratio for images by segmenting an image into non-overlapping segments called edge and non-edge segments and applying different compression depths for these segments. In an edge segment (a region that contains important information) the compression ratio is reduced to prevent loss of information, whereas in a non-edge segment (a smooth region which does not have important information), a high compression ratio is achieved and for encryption a non linear chaotic map is used. The performance of the proposed system is quantified using the peak signal-to-noise ratio to test the compression ratio and also the encrypted image has huge key space which makes harder for hacker to decrypting it using wrong key.

In today’s world of electronic revolution, digital images play an important role in consumer electronics. The need for storing images grows day to day. Compression of digital images plays an important role in storing the images. Due to compression the memory occupied by the images gets reduced and so that we can store more images in the available memory space. Also compression results in encoding of images which itself offer a security on transaction. This paper deals with a clear note on various aspects regarding compression and various compression techniques used and their implementation.

2015

This paper presents a novel method for providing security by compressing the encrypted images based on auxiliary information. The proposed method encrypts the uncompressed input image using chaos encryption algorithm and also generates auxiliary information using modulo-256 encryption. The auxiliary information generated is used for data compression and also for image reconstruction of the original image. The channel provider compressed the encrypted information using quantization process and it is carried out with the help of some optimal parameters derived from a part of auxiliary information and compression ratiodistortion criteria. The compressed data includes an encrypted sub-image, the quantized data, the quantization parameters and the part of encrypted auxiliary information. The receiver reconstructed the original image by utilizing the compressed encrypted information with secret key. The hidden bits are extracted from encrypted encoded version of binary map and then an app...

2015

The general encryption mechanism involves conversion of plain text into cipher text and decryption as vice versa, as well as multimedia(such as images, video, etc.,) the momentous aspect over here is that the converted cipher text always produces greater size than the original plain text. As there are innumerable number of internet users these days, more memory is accumulated in this process unnecessarily. To avoid such unnecessary accumulation of data we implement some data compression techniques over this encrypted data and also provide security mechanisms for the same and then send over the internet. But as we have many compression tools available in the open market, they fail to provide the security for the data at the same time. The same process can be implemented for the image encryption process. By encoding an image and compressing this encoded image along with security operations. Thus decryption provides the at most security for the data over the network. All the above disc...