scholarly journals A novel architecture with scalable security having expandable computational complexity for stream ciphers

2017 ◽  
Vol 30 (4) ◽  
pp. 459-475
Author(s):  
Prathap Siddavaatam ◽  
Reza Sedaghat
Keyword(s):  
Computational Complexity ◽  
Nonlinear System ◽  
Linear Algebra ◽  
Stream Cipher ◽  
Algebraic Degree ◽  
Stream Ciphers ◽  
Polynomial Equations ◽  
Hardware Complexity ◽  
Multivariate Polynomial ◽  
Algebraic Cryptanalysis

Stream cipher designs are difficult to implement since they are prone to weaknesses based on usage, with properties being similar to one-time pad besides keystream is subjected to very strict requirements. Contemporary stream cipher designs are highly vulnerable to algebraic cryptanalysis based on linear algebra, in which the inputs and outputs are formulated as multivariate polynomial equations. Solving a nonlinear system of multivariate equations will reduce the complexity, which in turn yields the targeted secret information. Recently, Addition Modulo has been suggested over logic XOR as a mixing operator to guard against such attacks. However, it has been observed that the complexity of Modulo Addition can be drastically decreased with the appropriate formulation of polynomial equations and probabilistic conditions. A new design for Addition Modulo is proposed. The framework for the new design is characterized by user-defined expandable security for stronger encryption and does not impose changes in existing layout for any stream cipher such as SNOW 2.0, SOSEMANUK, CryptMT, Grain Family, etc. The structure of the proposed design is highly scalable, which boosts the algebraic degree and thwarts the probabilistic conditions by maintaining the original hardware complexity without changing the integrity of the Addition Modulo.

scholarly journals Algebraic Cryptanalysis Scheme of AES-256 Using Gröbner Basis

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Kaixin Zhao ◽  
Jie Cui ◽  
Zhiqiang Xie
Keyword(s):  
Gröbner Basis ◽  
Variable Order ◽  
Polynomial Equations ◽  
Construction Process ◽  
Grobner Basis ◽  
Multivariate Polynomial ◽  
Algebraic Cryptanalysis ◽  
Term Order ◽  
Basis Construction ◽  
Depth Study

The zero-dimensional Gröbner basis construction is a crucial step in Gröbner basis cryptanalysis on AES-256. In this paper, after performing an in-depth study on the linear transformation and the system of multivariate polynomial equations of AES-256, the zero-dimensional Gröbner basis construction method is proposed by choosing suitable term order and variable order. After giving a detailed construction process of the zero-dimensional Gröbner basis, the necessary theoretical proof is presented. Based on this, an algebraic cryptanalysis scheme of AES-256 using Gröbner basis is proposed. Analysis shows that the complexity of our scheme is lower than that of the exhaustive attack.

scholarly journals Algebraic cryptanalysis of a small-scale version of stream cipher Lex

2010 ◽  
Vol 4 (2) ◽  
pp. 49 ◽  
Author(s):  
V. Velichkov ◽  
V. Rijmen ◽  
B. Preneel
Keyword(s):  
Stream Cipher ◽  
Small Scale ◽  
Algebraic Cryptanalysis

scholarly journals What Can You Do with a Rock? Affordance Extraction via Word Embeddings

2017 ◽  
Author(s):  
Nancy Fulda ◽  
Daniel Ricks ◽  
Ben Murdoch ◽  
David Wingate
Keyword(s):  
Reinforcement Learning ◽  
Computational Complexity ◽  
Linear Algebra ◽  
Autonomous Agents ◽  
Common Knowledge ◽  
Search Space ◽  
Word Embeddings ◽  
Knowledge Database ◽  
Learning Agent ◽  
Action Spaces

Autonomous agents must often detect affordances: the set of behaviors enabled by a situation. Affordance extraction is particularly helpful in domains with large action spaces, allowing the agent to prune its search space by avoiding futile behaviors. This paper presents a method for affordance extraction via word embeddings trained on a tagged Wikipedia corpus. The resulting word vectors are treated as a common knowledge database which can be queried using linear algebra. We apply this method to a reinforcement learning agent in a text-only environment and show that affordance-based action selection improves performance in most cases. Our method increases the computational complexity of each learning step but significantly reduces the total number of steps needed. In addition, the agent's action selections begin to resemble those a human would choose.

scholarly journals Performance and Statistical Analysis of Stream ciphers in GSM Communications

2020 ◽  
Vol 16 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Nagendar Yerukala ◽  
V Kamakshi Prasad ◽  
Allam Apparao
Keyword(s):  
Statistical Analysis ◽  
Stream Cipher ◽  
Statistical Tests ◽  
Stream Ciphers ◽  
Test Suite ◽  
Secret Key ◽  
Initial State ◽  
Detailed Statistical Analysis ◽  
Almost All ◽  
The Given

For a stream cipher to be secure, the keystream generated by it should be uniformly random with parameter 1/2.Statistical tests check whether the given sequence follow a certain probability distribution. In this paper, we perform a detailed statistical analysis of various stream ciphers used in GSM 2G,3G, 4G and 5G communications. The sequences output by these ciphers are checked for randomness using the statistical tests defined by the NIST Test Suite. It should also be not possible to derive any information about secret key and the initial state ofthe cipher from the keystream. Therefore, additional statisticaltests based on properties like Correlation between Keystreamand Key, and Correlation between Keystream and IV are also performed. Performance analysis of the ciphers also has been done and the results tabulated. Almost all the ciphers pass thetests in the NIST test suite with 99% confidence level. For A5/3stream cipher, the correlation between the keystream and key is high and correlation between the keystream and IV is low when compared to other ciphers in the A5 family.

The computational complexity of some problems of linear algebra

1997 ◽  
pp. 451-462 ◽  
Author(s):  
Jonathan F. Buss ◽  
Gudmund S. Frandsen ◽  
Jeffrey O. Shallit
Keyword(s):  
Computational Complexity ◽  
Linear Algebra

scholarly journals A key exchange protocol relying on polynomial maps

2019 ◽  
Vol 11 (01) ◽  
pp. 1950003
Author(s):  
Koichiro Akiyama ◽  
Shuhei Nakamura ◽  
Masaru Ito ◽  
Noriko Hirata-Kohno
Keyword(s):  
Key Exchange ◽  
System Of Equations ◽  
Polynomial Equations ◽  
Key Exchange Protocol ◽  
Multivariate Polynomial ◽  
Key Recovery ◽  
Polynomial Maps ◽  
Key Recovery Attacks

In this paper, we propose a key exchange protocol using multivariate polynomial maps whose security relies on the hardness in finding a solution to a certain system of nonlinear polynomial equations. Under the hardness assumption of solving the system of equations, we prove that our protocol is secure against key recovery attacks by passive attackers if the protocol is established honestly.

scholarly journals On Distinguishing Attack Against the Reduced Version of the Cipher Nlsv2

2012 ◽  
Vol 53 (1) ◽  
pp. 21-32
Author(s):  
Michal Braško ◽  
Jaroslav Boor
Keyword(s):  
Stream Cipher ◽  
Stream Ciphers ◽  
Web Page ◽  
Security Issue ◽  
Phase 3 ◽  
Distinguishing Attack ◽  
De Vries ◽  
Practical Demonstration

ABSTRACT The Australian stream cipher NLSv2 [Hawkes, P.-Paddon, M.-Rose, G. G.-De Vries, M. W.: Primitive specification for NLSv2, Project eSTREAM web page, 2007, 1-25] is a 32-bit word oriented stream cipher that was quite successful in the stream ciphers competition-the project eSTREAM. The cipher achieved Phase 3 and successfully accomplished one of the main requirements for candidates in Profile 1 (software oriented proposals)-to have a better performance than AES in counter mode. However the cipher was not chosen into the final portfolio [Babbage, S.-De Canni`ere, Ch.-Canteaut, A.-Cid, C.-Gilbert, H.-Johansson, T.-Parker, M.-Preneel, B.-Rijmen, V.-Robshaw, M.: The eSTREAM Portfolio, Project eSTREAM web page, 2008], because its performance was not so perfect when comparing with other finalist. Also there is a security issue with a high correlation in the used S-Box, which some effective distinguishers exploit. In this paper, a practical demonstration of the distinguishing attack against the smaller version of the cipher is introduced. In our experiments, we have at disposal a machine with four cores (Intel® CoreTM Quad @ 2.66 GHz) and single attack lasts about 6 days. We performed successful practical experiments and our results demonstrate that the distingushing attack against the smaller version is working.

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