Seyed Mohammad Seyedzadeh

A fast color image encryption algorithm based on coupled two-dimensional piecewise chaotic map

In recent years, a variety of chaos-based image cryptosystems have been proposed. Owing to the exceptionally desirable properties of mixing and sensitivity to initial conditions and parameters of chaotic maps, chaos-based encryption has suggested a new and efficient way to deal with the intractable problem of fast and highly secure image encryption. This paper proposes a novel chaos-based image encryption algorithm to encrypt color images by using a Coupled Two-dimensional Piecewise Nonlinear Chaotic Map, called CTPNCM, and a masking process. Distinct characteristics of the algorithm are high security, high sensitivity, and high speed that can be applied in encryption of color images. In order to generate the initial conditions and parameters of the CTPNCM, 256-bit long external secret key is used. Computer simulations confirm that the new algorithm has high security and is very fast for practical image encryption. It is demonstrated that the number of pixel change rate (NPCR), the unified average changing intensity (UACI), and entropy can satisfy security and performance requirements (NPCR>0.99672, UACI>0.334904, Entropy>7.99921). Experimental results reveal the fact that the proposed algorithm yields better security performance in comparison to the results obtained from other algorithms.

A novel image encryption based on row-column, masking and main diffusion processes with hyper chaos

In this paper, a novel algorithm for image encryption based on the hyper-chaotic system is proposed. In order to generate the initial conditions of the hyper-chaotic system, 256-bit long external secret key is used. The algorithm consists of three main sections. In the first section, instead of encrypting each pixel, the rows and columns of the image are encrypted using a row-column algorithm. In order to reach higher sensitivity, higher complexity and higher security, the second section employs masking process which is applied to each quarter of the image (i.e. sub-images) that is to be encrypted, using that sub-image data itself and one of the other sub-images and the average data of other quarters of image. Finally in the last diffusion section, the four most significant bit planes will be encrypted. Experimental results and performance analysis prove the viability of this cryptography based on privacy, integrity and authenticity. It is demonstrated that 2D Correlation Coefficients (CC), Mean Absolute Error (MAE), Encryption Quality (EQ), Mean Square Error (MSE), Peak Signal-to-Noise Ratio (PSNR), the Number of Pixel Change Rate (NPCR), the Unified Average Changing Intensity (UACI), entropy and decryption quality can satisfy security and performance requirements (CC < 0.0032, MAE > 80, EQ > 210.90, MSE > 9555, PSNR < 8.3875, NPCR > 99.61243%, UACI > 33.47573% and Entropy > 7.99734). It can be seen that this algorithm yields better security performance in comparison to the results obtained from other algorithms.

CAFO: Cost aware flip optimization for asymmetric memories

Phase Change Memory (PCM) and spin-transfer torque random access memory (STT-RAM) are emerging as new memory technologies to replace DRAM and NAND flash that are impeded by physical limitations. Programming PCM cells degrades their endurance while programming STT-RAM cells incurs a high bit error rate. Accordingly, several schemes have been proposed to service write requests while programing as few memory cells as possible. Nevertheless, those schemes did not address the asymmetry in programming memory cells that characterizes both PCM and STT-RAM. For instance, writing a bit value of 0 on PCM cells is more detrimental to endurance than 1 while writing a bit value of 1 on STT-RAM cells is more prone to error than 0. In this paper, we propose CAFO as a new cost aware flip reduction scheme. Essentially, CAFO encompasses a cost model that computes the cost of servicing write requests through assigning different costs to each cell that requires programming. Subsequently, CAFO encodes the data to be written into a form that incurs less cost through its cost aware encoding module. Overall, CAFO is capable of cutting down the write cost by up to 65% more than existing schemes.

RGB color image encryption based on Choquet fuzzy integral

HighlightsThis research presents a new image encryption scheme using the Choquet fuzzy integral based keystream generator.The properties of the dynamical keystream generator with mathematical analysis are proved rigorously.Experimental results prove the security and the validity of the proposed algorithm. In recent years, one can see an increasing interest in the security of digital images. This research presents a new RGB color image encryption using keystream generator based on Choquet fuzzy integral (CFI). The properties of the dynamical keystream generator with mathematical analysis are presented in this work. In the proposed method, the CFI is first used to generate pseudo-random keystreams. Then, each of the color pixels is decomposed into three gray-level components. The output of the CFI is used to randomly shift the bits of three gray-level components. Finally, three components of RGB color pixels and the generated keystream are coupled to encrypt the permuted components. Performance aspects of the proposed algorithm such as the entropy analysis, differential analysis, statistical analysis, cipher random analysis, and cipher sensitivity analysis are introduced to evaluate the security of the new scheme. The experimental results reveal the fact that the proposed algorithm is suitable for practical use in protecting the security of digital image information distributed via the Internet.

Improving Bit Flip Reduction for Biased and Random Data

Nonvolatile memory technologies such as Spin-Transfer Torque Random Access Memory (STT-RAM) and Phase Change Memory (PCM) are emerging as promising replacements to DRAM. Before deploying STT-RAM and PCM into functional systems, a number of challenges still remain must be addressed. Specifically, both require relatively high write energy, STT-RAM suffers from high bit error rates and PCM suffers from low endurance. A common solution to overcome those challenges is to minimize the number of bits changed per write. In this paper, we propose and evaluate the hybrid coset encoder to efficiently improve and balance the bit flip reduction for biased and unbiased data. The main core of the coset encoder consists of biased and unbiased vectors which maps the data input to a larger set of data vectors. Subsequently, the intermediate data vector that yields the least number of differences when compared to the currently stored data is selected. Our evaluation shows that hybrid coset encoder reduces bit flips by up to 25 percent over a baseline differential writing scheme. Further, our proposed scheme reduces bit flips by up to 20 percent over the leading bit-flip minimization scheme for biased data, while achieving very low decoding overhead similar to the Flip-N-Write scheme.

PRES: pseudo-random encoding scheme to increase the bit flip reduction in the memory

Nonvolatile memory technologies such as Phase Change Memory (PCM) and Spin-Transfer Torque Random Access Memory (STT-RAM) are emerging as promising replacements to DRAM. Before deploying STT-RAM and PCM into functional systems, a number of challenges still remain. Specifically, both require relatively high write energy, STT-RAM suffers from high bit error rates and PCM suffers from low endurance. A common solution to overcome those challenges is to minimize the number of bits changed per write. In this work, we introduce Pseudo-Random Encoding Scheme (PRES) to minimize the number of bit changes during memory writes. PRES maps the write data vector into an intermediate highly random set of data vectors. Subsequently, the intermediate data vector that yields the least number of differences when compared to the currently stored data is selected. Our evaluation shows that PRES reduces bit flips by up to 25% over a baseline differential writing scheme. Further, PRES reduces bit flips by 15% over the leading bit-flip minimization scheme, while decreasing encoding and decoding complexities by more than 90%.

Counter-Based Tree Structure for Row Hammering Mitigation in DRAM

Scaling down DRAM technology degrades cell reliability due to increased coupling between adjacent DRAM cells, commonly referred to as crosstalk. Moreover, high access frequency of certain cells (hot cells) may cause data loss in neighboring cells in adjacent rows due to crosstalk, which is known as row hammering. In this work, the goal is to mitigate row hammering in DRAM cells through a Counter-Based Tree (CBT) approach. This approach uses a tree of counters to detect hot rows and then refreshes neighboring cells. In contrast to existing deterministic solutions, CBT utilizes fewer counters that makes it practically feasible to be implemented on-chip. Compared to existing probabilistic approaches, CBT more precisely refreshes rows vulnerable to row hammering based on their access frequency. Experimental results on workloads from three benchmark suites show that CBT can reduce the refresh energy by more than 60 percent and nearly 70 percent in comparison to leading probabilistic and deterministic approaches, respectively. Furthermore, hardware evaluation shows that CBT can be easily implemented on-chip with only a nominal overhead.

Image encryption algorithm based on Choquet Fuzzy Integral with self-adaptive pseudo-random number generator

In this paper, a novel algorithm for image encryption based on Choquet Fuzzy Integral (CFI) with Self-adaptive Pseudo-random Number Generator suggests using one half of image data for encryption of the other half of the image reciprocally. The major core of the encryption algorithm is a pseudo-random number generator based on the CFI. In order to generate the initial parameters of the CFI of one half of the image, 128-bit-long external secret key and the other half of the image data are used. Security and performance of the proposed algorithm were both tested, and satisfactory results have been achieved. It is observed that the number of pixel change rate (NPCR), the unified average changing intensity (UACI), and entropy, can satisfy security and performance requirements (NPCR > 0.9961, UACI > 0.3347, Entropy > 7.9999). Furthermore, the proposed image encryption algorithm successfully passes ENT test which prove the robustness of the algorithm.

Leveraging ECC to Mitigate Read Disturbance, False Reads and Write Faults in STT-RAM

Designing reliable systems using scaled Spin-Transfer Torque Random Access Memory (STT-RAM) has become a significant challenge as the memory technology feature size is scaled down. The introduction of a more prominent read disturbance is a key contributor in this reliability challenge. However, techniques to address read disturbance are often considered in a vacuum that assumes other concerns like transient read errors (false reads) and write faults do not occur. This paper studies several techniques that leverage ECC to mitigate persistent errors resulting from read disturbance and write faults of STT-RAM while still considering the impact of transient errors of false reads. In particular, we study three policies to enable better-than-conservative read disturbance mitigation. The first policy, write after error (WAE), uses ECC to detect errors and write back data to clear persistent errors. The second policy, write after persistent error (WAP), filters out false reads by reading a second time when an error is detected leading to trade-off between write and read energy. The third policy, write after error threshold (WAT), leaves cells with incorrect data behind (up to a threshold) when the number of errors is less than the ECC capability. To evaluate the effectiveness of the different schemes and compare with the simple previously proposed scheme of writing after every read (WAR), we model these policies using Markov processes. This approach allows the determination of appropriate bit error rates in the context of both persistent and transient errors to accurately estimate the system reliability and the energy consumption of different error correction approaches. Our evaluations show that each of these policies provides benefits for different error scenarios. Moreover some approaches can save energy by an average of 99.5%, while incurring the same reliability as other approaches.

Image encryption scheme based on Choquet fuzzy integral with pseudo-random keystream generator

This paper presents a novel fast algorithm, which consists of two parts, namely, Choquet fuzzy integral for generation of a pseudo-random keystream, and a self-adaptive masking process for increasing shuffling pixels of the image. The first part, which is the major core of the encryption algorithm, is a pseudo-random keystream generator based on the Choquet fuzzy integral. A 128-bit key is used for generating the parameters of the Choquet fuzzy integral, and increasing the security of the proposed algorithm. The second part uses one half of image data for shuffling of the other half of image reciprocally and aims to increase the image entropy. It is demonstrated that the number of pixel change rate (NPCR) and the unified average changing intensity (UACI) can satisfy security and performance requirements (NPCR > 0.9969, UACI > 0.3349). The experimental results obtained for the USC-SIPI image database, have shown the high performance on the sensitivity, speed and security of the proposed algorithm