Cipher

About: Cipher is a research topic. Over the lifetime, 9409 publications have been published within this topic receiving 110309 citations. The topic is also known as: cypher & cryptographic algorithm.

Optical Bit-Plane-Based 3D-JST Cryptography Algorithm With Cascaded 2D-FrFT Encryption for Efficient and Secure HEVC Communication

Abstract: The rapid growth of multimedia communication systems has expanded the High-Efficiency Video Coding (HEVC) security applications precipitously. Therefore, there is an urgent, elevated need to protect and secure the HEVC content during streaming and communication over insecure channels to ensure the privacy of HEVC data against intruders and attackers. This paper introduces an optical HEVC cipher algorithm based on bit-plane 3D-JST (Three-Dimensional Jigsaw Transform) and multistage 2D-FrFT (Two-Dimensional Fractional Fourier Transform) encryption. The main advantage of employing 3D-JST is its unitary transform that has an inverse transform used to reorganize the HEVC frame-blocks in an indiscriminately way. The proposed algorithm embraces the cascaded 2D-FrFT encryption in the optical domain using a single arbitrary phase code; to be executed all optically with a lone lens. The suggested algorithm utilizes the two 2D-FrFT stages with distinct kernels in mutually dimensions separated by employing the arbitrary phase code. A foregoing bit-plane permutation stage is conducted on the input HEVC frames before the 3D-JST and 2D-FrFT processes to accomplish a high robustness and security level. To validate the efficacy of the proposed cryptography algorithm for secure HEVC streaming, a comprehensive evaluation framework has been introduced and followed to (a) test HEVC streams against different statistical cryptographic metrics, (b) compare the proposed algorithm with recent related works whether optical-based or digital-based algorithms and (c) study the impact of different security attacks on its performance. The evaluation results show a secure and efficient proposed cryptography algorithm that outperforms the conventional and related cryptography algorithms in terms of all examined evaluation metrics.

On the Security of Multiple Encryption or CCA-security+CCA-security=CCA-security?

Abstract: In a practical system, a message is often encrypted more than once by different encryptions, here called multiple encryption, to enhance its security. Additionally, new features may be achieved by multiple encrypting a message, such as the key-insulated cryptosystems and anonymous channels. Intuitively, a multiple encryption should remain “secure”, whenever there is one component cipher unbreakable in it. In NESSIE’s latest Portfolio of recommended cryptographic primitives (Feb. 2003), it is suggested to use multiple encryption with component ciphers based on different assumptions to acquire long term security. However, in this paper we show this needs careful discussion, especially, this may not be true according to adaptive chosen ciphertext attack (CCA), even with all component ciphers CCA-secure. We define an extended model of (standard) CCA called chosen ciphertext attack for multiple encryption (ME-CCA) emulating partial breaking of assumptions, and give constructions of multiple encryption satisfying ME-CCA-security. We further relax CCA by introducing weak ME-CCA (ME-wCCA) and study the relations among these definitions, proving ME-wCCA-security can be acquired by combining IND-CCA-secure component ciphers together. We then apply these results to key-insulated cryptosystem.

Khudra: A New Lightweight Block Cipher for FPGAs

Abstract: The paper shows that designing lightweight block ciphers for the increasingly popular Field Programmable Gate Arrays (FPGAs) needs a new revisit. It shows that due to the underlying FPGA architecture many popular techniques for lightweight block ciphers which work on Application Specific Integrated Circuits (ASICs) does not apply to FPGAs. The paper identifies new methods and design criteria for lightweight block ciphers operating on FPGAs. Using these guidelines, a new block cipher Khudra based on the recursive Feistel structure is designed, which has a 64 bit block size and 80 bits of key. Rigorous cryptanalysis, ranging from linear and differential cryptanalysis to more powerful attacks like impossible differential, related key attacks etc. have been performed to justify that 18 rounds of Khudra provide sufficient security margin. Finally, the cipher has been implemented in two different flavors, Khudra-I and Khudra-II, on low cost FPGAs like Xilinx Spartan-III XC3S400 and extensively compared with other contemporary ciphers like PRESENT, Piccolo and compact implementations of other standard cipher like AES, Camellia etc. The implementation results show that Khudra requires at least around 45% less slices and 29% less AT product compared to round wise implementation of any of the contemporary lightweight block cipher.

Differential Fault Intensity Analysis on PRESENT and LED Block Ciphers

Abstract: Differential Fault Intensity Analysis DFIA is a recently introduced fault analysis technique. This technique is based on the observation that faults are biased and thus are non-uniformly distributed over the cipher state variables. The adversary uses the fault bias as a source of leakage by controlling the intensity of fault injection. DFIA exploits statistical analysis to correlate the secret key to the biased fault behavior. In this work, we show a DFIA attack on two lightweight block ciphers: PRESENT and LED. For each algorithm, our research analyzes the efficiency of DFIA on a round-serial implementation and on a nibble-serial implementation.We show that all algorithms and all implementation variants can be broken with 10 to 36 fault intensity levels, depending on the case. We also analyze the factors that affect the convergence of DFIA. Wei¾?show that there is a trade-off between the number of required plaintexts, and the resolution of the fault-injection equipment. Thus, an adversary with lower-quality fault-injection equipment may still be as effective as an adversary with high-quality fault-injection equipment, simply by using additional encryptions. This confirms that DFIA is effective against a range of algorithms using a range of fault injection techniques.

Espresso: A stream cipher for 5G wireless communication systems

Abstract: The demand for more efficient ciphers is a likely to sharpen with new generation of products and applications. Previous cipher designs typically focused on optimizing only one of the two parameters - hardware size or speed, for a given security level. In this paper, we present a methodology for designing a class of stream ciphers which takes into account both parameters simultaneously. We combine the advantage of the Galois configuration of NLFSRs, short propagation delay, with the advantage of the Fibonacci configuration of NLFSRs, which can be analyzed formally. According to our analysis, the presented stream cipher Espresso is the fastest among the ciphers below 1500 GE, including Grain-128 and Trivium.