• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.05a
• /
• pp.433-436
• /
• 2009

Many researchers had made a diversity of attempts for generating pseudorandom sequences such as the method of using LFSR whose characteristic polynomial is a primitive polynomial, of using Cellular Automata and of using quadratic functions. In this paper, we can analyze and characterize the methods for generating maximal period pseudorandom sequences constructed by quadratic functions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2010.10a
• /
• pp.759-761
• /
• 2010

In this paper, we propose a video encryption method using pseudo-random numbers based on MLCA(Maximal length Cellular Automata). Firstly, we generate a basis image which is composed with pseudo-random numbers, using MLCA. Futhermore, The original video is encrypted by computing XOR operation between the basis image and each frame of original video. The video encryption is conducted in accordance with one or two rules, and is evaluated.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.17 no.2
• /
• pp.357-364
• /
• 2022

A pseudo-random number generator (PRNG) is a program used when a large amount of random numbers is needed. It is used to generate symmetric keys in symmetric key cryptography systems, generate public key pairs in public key cryptography or digital signatures, and generate columns used for padding with disposable pads. Cellular Automata (CA), which is useful for specific representing nonlinear dynamics in various scientific fields, is a discrete and abstract computational system that can be implemented in hardware and is applied as a PRNG that generates keys in cryptographic systems. In this paper, I propose an algorithm for synthesizing a programmable 5-neighbor CA based PRNG that can effectively generate a nonlinear sequence using 5-neighbor CA with the radius of the neighboring cell increased by 2.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.05a
• /
• pp.441-445
• /
• 2009

In this paper we propose the method of generating the maximum length sequence based on Self Programmable Cellular Automata. Recently there is a research trend such that increased CA dimensionality and PCA which applies different rules on the same cell at different time steps can make a sequence with a long period. By changing a cell's state transition rules to give the cell dynamic energy at each time step, we can make the period of a sequence longer and the randomness of a sequence higher.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.17 no.2
• /
• pp.333-342
• /
• 2022

Cellular Automata (CA) is a discrete and abstract computational model that is being applied in various fields. Applicable as an excellent pseudo-random sequence generator, CA has recently developed into a basic element of cryptographic systems. Several studies on CA-based stream ciphers have been conducted and it has been observed that the encryption strength increases when the radius of a CA's neighbor is increased when appropriate CA rules are used. In this paper, among CAs that can be applied as a one-dimensional pseudo-random number sequence generator (PRNG), one-dimensional 5-neighbor CAs are classified according to the connection state of their neighbors, and the ignition relationship of the characteristic polynomial is obtained. Also this paper propose a synthesis algorithm for an asymmetric 1-D linear 5-neighbor MLCA in which the radius of the neighbor is increased by 2 using the one-dimensional 3-neighbor 90/150 CA state transition matrix.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.5 no.4
• /
• pp.418-424
• /
• 2010

Many researchers studied methods for the generation of maximum length pseudo random sequences. Sabater et al. analyzed shrunken sequences which are effectively generated by SG(Shrinking Generator) using CA(Cellular Automata). In this paper we propose a new SG which is called LCSG(LFSR and CA based Shrinking Generator) using an LFSR with control register and CA with generator register. The proposed shrunken sequences generated by LCSG have longer periods and high complexities than the shrunken sequences generated by the known method. And we analyze the generated sequences using LCSG.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.24 no.1
• /
• pp.51-58
• /
• 2014

A LFSR is commonly used for various stream cryptography applications to generate random numbers. A Leap-ahead LFSR was presented to generate a multi-bits random number per cycle. It only requires a single LFSR and it has an advantages in hardware complexity. However, it suffers from the significant reduction of maximum period of the generated random numbers. This paper presents the new segmented Leap-ahead LFSR to solve this problem. It consists of two segmented LFSRs. We prove the efficiency of the proposed segmented architecture using the precise mathematical analysis. We also demonstrate the proposed comparison results with other counterparts using Xinilx Vertex5 FPGA. The proposed architecture can increase 2.5 times of the maximum period of generated random numbers compared to the typical Leap-ahead architecture.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.14 no.5
• /
• pp.1001-1008
• /
• 2019

A high-quality pseudorandom sequence generation is an important part of many cryptographic applications, including encryption protocols. Therefore, a pseudorandom number generator (PRNG) is an essential element for generating key sequences in a cryptosystem. A PRNG must effectively generate a large, high-quality random data stream. It is well known that the bitstreams output by the CA-based PRNG are more random than the bitstreams output by the LFSR-based PRNG. In this paper, we prove that the complemented CA derived from 90/150 maximum length cellular automata(MLCA) is a MLCA to design a PRNG that can generate more secure bitstreams and extend the key space in a secret key cryptosystem. Also we give a method for calculating the cell positions outputting a nonlinear sequence with maximum period in complemented MLCA derived from a 90/150 MLCA and a complement vector.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.6
• /
• pp.1469-1475
• /
• 2010

This paper presents a problem of existing encryption methods using pseudo-random numbers based on MLCA or complemented MLCA and proposes a method to resolve this problem. The existing encryption methods have a problem which the edge of original image appear on encrypted image because the image have color similarity of adjacent pixels. In this proposed method, we transform the value and spatial coordinates of all pixels by using pseudo-random numbers based on MLCA. This method can resolve the problem of existing methods and improve the level of encryption by encrypting pixel coordinates and pixel values of original image. The effectiveness of the proposed method is proved by conducting histogram and key space analysis.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2010.05a
• /
• pp.141-143
• /
• 2010

This paper presents a problem of the existing encryption method using MLCA or complemented MLCA and propose a method to resolve this problem. With the existing encryption methods, the result of encryption is affected by the original image because of spatial redundancy of adjacent pixels. In this proposed method, we transform spatial coordinates of all pixels into encrypted coordinates. We also encrypt color values of the original image by operating XOR with pseudo-random numbers. This can solve the problem of existing methods and improve the levels of encryption by randomly encrypting pixel coordinates and pixel values of original image. The effectiveness of the proposed method is proved by conducting histogram, key space analysis.