Sharif Digital Repository

Cryptographic algorithms utilize finite-field arithmetic operations in their computations. Due to the constraints of the nodes which benefit from the security and privacy advantages of these algorithms in sensitive applications, these algorithms need to be lightweight. One of the well-known bases used in sensitive computations is dual basis (DB). In this brief, we present low-complexity superserial architectures for the DB multiplication over GF (2m). To the best of our knowledge, this is the first time that such a multiplier is proposed in the open literature. We have performed complexity analysis for the proposed lightweight architectures, and the results show that the hardware complexity... 

SIMON is a family of 10 lightweight block ciphers published by Beaulieu et al. from the United States National Security Agency (NSA). A cipher in this family with K-bit key and N-bit block is called SIMONN/K. We present several linear characteristics for reduced-round SIMON32/64 that can be used for a key-recovery attack and extend them further to attack other variants of SIMON. Moreover, we provide results of key recovery analysis using several impossible differential characteristics starting from 14 out of 32 rounds for SIMON32/64 to 22 out of 72 rounds for SIMON128/256. In some cases the presented observations do not directly yield an attack, but provide a basis for further analysis for... 

This paper presents cube and dynamic cube attacks on reduced-round lightweihgt block cipher SIMON32/64, proposed by U.S. National Security Agency in 2013. Cube attack is applied to 17 rounds out of 32 rounds of SIMON using a 13-round distinguisher and dynamic cube breaks 14 rounds out of 32 rounds using 10-round distinguishers. Both attacks recover the full 64-bit key of the cipher in a practical time complexity  

In this paper we derive a new upper bound on the quantum key distillation capacity. This upper bound is an extension of the classical bound of Gohari and Anantharam on the source model problem. Our bound strictly improves the quantum extension of reduced intrinsic information bound of Christandl et al. Although this bound is proposed for quantum settings, it also serves as an upper bound for the special case of classical source model, and may improve the bound of Gohari and Anantharam. The problem of quantum key distillation is one in which two distant parties, Alice and Bob, and an adversary, Eve, have access to copies of quantum systems A, B, E respectively, prepared jointly according to... 

In a multistage secret sharing (MSSS) scheme, the authorised subsets of participants could recover a number of secrets in different stages. A one-stage multisecret sharing (OSMSS) scheme is a special case of MSSS schemes in which all the secrets are recovered simultaneously. In these schemes, in addition to the individual shares, the dealer should provide the participants with a number of public values associated with the secrets. The less the number of public values, the more efficient is the scheme. It is desired that the MSSS and OSMSS schemes provide computational security. In this study, the authors show that in the OSMSS schemes any unauthorised coalition of the participants can reduce... 

The HIGHT algorithm is a 64-bit block cipher with 128-bit key length, at CHES'06 as a lightweight cryptographic algorithm. In this paper, a new related-key impossible differential attack on the full-round algorithm is introduced. Our cryptanalysis requires time complexity of 2127.276 HIGHT evaluations which is slightly faster than exhaustive search attack. This is the first related-key impossible differential cryptanalysis on the full-round HIGHT block cipher. Copyright  

Privacy is faced with serious challenges in the ubiquitous computing world. In order to handle this problem, some researchers in recent years have focused on design and analysis of privacy-friendly ultralightweight authentication protocols. Although the majority of these schemes have been broken to a greater or lesser extent, most of these attacks are based on ad-hoc methods that are not extensible to a large class of ultralightweight protocols. So this research area still suffers from the lack of structured cryptanalysis and evaluation methods. In this paper, we introduce new frameworks for full disclosure attacks on ultralightweight authentication protocols based on new concepts of... 

We propose an effective blind image steganalysis based on contourlet transform and Zernike moments that improves the detection accuracy of universal image steganalysis methods. The proposed method examines randomness in the test image to distinguish between the stego and non-stego images. The suspicious image is decomposed by contourlet transform, and then the absolute Zernike moments of contourlet subbands coefficients of the image and linear prediction error of each contourlet subband are extracted as features for steganalysis. These features are fed to a nonlinear SVM classifier with an RBF kernel to distinguish between cover and stego images. Experimental results show that the proposed... 

In this study, we review attribute-based ring signature schemes. Our proposal presents two contributions; the first one is security analysis of Wenqiang et al.'s scheme in 2009 by presenting an attack in which we show that their scheme is forgeable. The second contribution is an efficient attribute-based ring signature scheme with constant size and constant number of pairing operations. Our scheme is unconditionally anonymous and unforgeable in the standard model. The security of our proposal is based on Static Diffie Hellman (SDH) problem. Compared with the existing attribute-based ring signature scheme with constant size, the length of the signature and the pairing operations in our scheme... 

Security is a critical and vital task in WSNs. Recently, key management as the core of a secure communication has received lots of attention, but in most of the proposed methods security has been compromised in favor of reducing energy consumption. Consequently, perfect resiliency has not been achieved by most of the previous works. Hostile environment, ability of adversary to capture the nodes, and dead nodes with sensitive data scattered in the region, calls for a more secure and yet practical method. This paper proposes a novel authentication scheme based on broadcast messages from BS to improve security of key management system. Through simulation it is shown that energy consumption of... 

In current ring signature schemes, there is no distinguishing about the ranks of members of the ring. This paper proposes a ring signature scheme which considers the members' rank values. We show our scheme is anonymous against full key exposure attack and unforgeable with respect to insider corruption in the standard model with the computational Diffie Hellman (CDH) and Subgroup Hiding (SGH) assumptions in bilinear groups  

One of the most important systems for providing anonymous communication is the Mix nets which should provide correctness and privacy as security requirements against active adversaries. In 2009, Zhong proposed a new mix net scheme which uses identity-based cryptographic techniques and proved that it has 'correctness' and 'privacy' properties in the semi-honest model. Since the semi-honest model is a very strong assumption for practical application, we show that if a user or the last mix server is corrupted, Zhong scheme does not provide privacy against an active adversary  

A large number of Wireless Sensor Network (WSN) security schemes have been proposed in the literature, relying primarily on symmetric key cryptography. To enable those, Random Key pre-Distribution (RKD) systems have been widely accepted. However, WSN nodes are vulnerable to physical compromise. Capturing one or more nodes operating with RKD would give the adversary keys to compromise communication of other benign nodes. Thus the challenge is to enhance resilience of WSN to node capture, while maintaining the flexibility and low-cost features of RKD. We address this problem, without any special-purpose hardware, proposing a new and simple idea: key splitting. Our scheme does not increase...