Synchronization of spatiotemporal semiconductor lasers and its application in color image encryption

Optical chaos is a topic of current research characterized by high-dimensional nonlinearity which is attributed to the delay-induced dynamics, high bandwidth and easy modular implementation of optical feedback. In light of these facts, which adds enough confusion and diffusion properties for secure communications, we explore the synchronization phenomena in spatiotemporal semiconductor laser systems. The novel system is used in a two-phase colored image encryption process. The high-dimensional chaotic attractor generated by the system produces a completely randomized chaotic time series, which is ideal in the secure encoding of messages. The scheme thus illustrated is a two-phase encryption method, which provides sufficiently high confusion and diffusion properties of chaotic cryptosystem employed with unique data sets of processed chaotic sequences. In this novel method of cryptography, the chaotic phase masks are represented as images using the chaotic sequences as the elements of the image. The scheme drastically permutes the positions of the picture elements. The next additional layer of security further alters the statistical information of the original image to a great extent along the three-color planes. The intermediate results during encryption demonstrate the infeasibility for an unauthorized user to decipher the cipher image. Exhaustive statistical tests conducted validate that the scheme is robust against noise and resistant to common attacks due to the double shield of encryption and the infinite dimensionality of the relevant system of partial differential equations.Comment: 20 pages, 11 figures; Article in press, Optics Communications (2011

Analysis Performance of Fast Image Encryption

Perkembangan teknologi mengakibatkan peningkatan kebutuhan pengiriman data melalui media internet. Banyak pengiriman data yang membutuhkan keamanan dalam pengirimannya untuk berbagai keperluan. Enkripsi data merupakan salah satu topic pengamanan yang banyak dilakukan penelitian dengan tujuan untuk mengamankan data yang dikirimkan melalui media internet. Salah satu data yang banyak digunakan adalah data citra. Citra merupakan data yang memiliki kapasitas besar dan memiliki sifat Perulangan yang tinggi sehingga dibutuhkan metode tertentu untuk melakukan proses enkripsi dan dekripsi citra. Permutasi dan difusi merupakan cara yang banyak digunakan untuk melakukan enkripsi citra. Permutasi bertujuan untuk mengacak posisi citra sedangkan difusi merubah nilai citra. Permutasi dan difusi banyak dilakukan sebagai dua tahap yang berbeda sehingga dibutuhkan dua kali pembacaan citra. Sebuah algoritma untuk menggabungkan proses permutasi dan difusi sehingga hanya diperlukan satu kali pembacaan citra untuk melakukan enkripsi telah diajukan. Selain permutasi dan difusi, fungsi chaos juga digunakan dalam algoritma tersebut karena kemampuannya untuk menghasilkan angka random yang sangat sensitif terhadap beberapa parameter. Dengan ide demikian, algoritma akan cepat untuk melakukan proses enkripsi dan dekripsi. Dalam penelitian ini dianalisis kinerja algoritma gabungan permutasi dan difusi menggunakan fungsi chaos. Analisis dilakukan dengan mengimplementasikan algoritma, mendapatkan waktu yang dibutuhkan untuk proses enkripsi dan dekripsi serta membandingkannnya dengan algoritma baku yang telah banyak digunakan, Advanced Encryption Standart (AES)

Joint block and stream cipher based on a modified skew tent map

Image encryption is very different from that of texts due to the bulk data capacity and the high redundancy of images. Thus, traditional methods are difficult to use for image encryption as their pseudo-random sequences have small space. Chaotic cryptography use chaos theory in specific systems working such as computing algorithms to accomplish dissimilar cryptographic tasks in a cryptosystem with a fast throughput. For higher security, encryption is the approach to guard information and prevent its leakage. In this paper, a hybrid encryption scheme that combines both stream and block ciphering algorithms is proposed in order to achieve the required level of security with the minimum encryption time. This scheme is based on an improved mathematical model to cover the defects in the previous discredited model proposed by Masuda. The proposed chaos-based cryptosystem uses the improved Skew Tent Map (STM) RQ-FSTM as a substitution layer. This map is based on a lookup table to overcome various problems, such as the fixed point, the key space restrictions, and the limitation of mapping between plain text and cipher text. It uses the same map as a generator to change the byte position to achieve the required confusion and diffusion effects. This modification improves the security level of the original STM. The robustness of the proposed cryptosystem is proven by the performance and the security analysis, as well as the high encryption speed. Depending on the results of the security analysis the proposed system has a better dynamic key space than previous ones using STM, a double encryption quality and a better security analysis than others in the literature with speed convenience to real-time applications

Roadmap on optical security

Postprint (author's final draft

Improved method for image security based on chaotic-shuffle and chaotic-diffusion algorithms

In this paper, we propose to enhance the security performance of the color image encryption algorithm which depends on multi-chaotic systems. The current cryptosystem utilized a pixel-chaotic-shuffle system to encode images, in which the time of shuffling is autonomous to the plain-image. Thus, it neglects to the picked plaintext and known-plaintext attacks. Also, the statistical features of the cryptosystem are not up to the standard. Along these lines, the security changes are encircled to make the above attacks infeasible and upgrade the statistical features also. It is accomplished by altering the pixel-chaotic-shuffle component and including another pixel-chaotic-diffusion system to it. The keys for diffusion of pixels are extracted from the same chaotic arrangements created in the past stage. The renovation investigations and studies are performed to exhibit that the refreshed version of cryptosystem has better statistical features and invulnerable to the picked plaintext and known plaintext attacks than the current algorithm

A Hierarchical Selective Encryption Technique in a Scalable Image Codec

International audienceModern still image codecs furnish more than just good distortion-rate performances. They must also provide some services. Scalability in resolution and quality, er- ror resilience and embedded bitstreams were among the first one to be available. There is still room for enhance- ment, especially when it comes to security-oriented fea- tures. Image encryption is one of the aspect of image security. This paper presents the embedding of an encryptionservice in a multiresolution lossless codec. Partial encryption is performed using ciphering only the keystone part of the codec algorithm, a quadtree decomposition. This results in a hierarchical encryption scheme, showing to be a good tradeoff between encryption speed, selective access and robustness