Improved Linear Cryptanalysis of Reduced-round SIMON

SIMON is a family of ten lightweight block ciphers published by Beaulieu et al.\ from U.S. National Security Agency (NSA). In this paper we investigate the security of SIMON against different variants of linear cryptanalysis techniques, i.e.\ classical and multiple linear cryptanalysis and linear hulls. We present a connection between linear- and differential characteristics as well as differentials and linear hulls in SIMON. We employ it to adapt the current known results on differential cryptanalysis of SIMON into the linear setting. In addition to finding a linear approximation with a single characteristic, we show the effect of the linear hulls in SIMON by finding better approximations that enable us to improve the previous results. Our best linear cryptanalysis employs average squared correlation of the linear hull of SIMON based on correlation matrices. The result covers 21 out of 32 rounds of SIMON32/64 with time and data complexity $2^{54.56}$ and $2^{30.56}$ respectively. We have implemented our attacks for small scale variants of SIMON and our experiments confirm the theoretical biases and correlation presented in this work. So far, our results are the best known with respect to linear cryptanalysis for any variant of SIMON

ESTABLISHED WAYS TO ATTACK EVEN THE BEST ENCRYPTION ALGORITHM

Which solution is the best – public key or private key encryption? This question cannot have a very rigorous, logical and definitive answer, so that the matter be forever settled :). The question supposes that the two methods could be compared on completely the same indicators – well, from my point of view, the comparison is not very relevant. Encryption specialists have demonstrated that the sizes of public key encrypted messages are much bigger than the encrypted message using private key algorithms. From this point of view, we can say that private key algorithms are more efficient than their newer counterparts. Looking at the issue through the eyeglass of the security level, the public key encryption have a great advantage of the private key variants, their level of protection, in the most pessimistic scenarios, being at least 35 time higher. As a general rule, each type of algorithm has managed to find its own market niche where could be applicable as a best solution and be more efficient than the other encryption model.Encryption, decryption, key, cryptanalysis, brute-force, linear, differential, algebra

KLEIN: A New Family of Lightweight Block Ciphers

Resource-efficient cryptographic primitives become fundamental for realizing both security and efficiency in embedded systems like RFID tags and sensor nodes. Among those primitives, lightweight block cipher plays a major role as a building block for security protocols. In this paper, we describe a new family of lightweight block ciphers named KLEIN, which is designed for resource-constrained devices such as wireless sensors and RFID tags. Compared to the related proposals, KLEIN has advantage in the software performance on legacy sensor platforms, while in the same time its hardware implementation can also be compact

Linear Cryptanalysis of Round Reduced SIMON

SIMON is a family of lightweight block ciphers that was proposed by U.S National Security Agency (NSA). A cipher in this family with $K$-bit key and $N$-bit block is called SIMON ${N}/{K}$. In this paper we analyze the security of SIMON against linear cryptanalysis. We present several linear characteristics for all variants of SIMON with reduced number of rounds. Our best linear characteristic covers SIMON 32/64 reduced to 13 rounds out of 32 rounds with the bias of $2^{-16}$. In addition, we describe a connection between linear and differential characteristics for SIMON. This connection is then exploited by using the differential characteristics of the previous work of Abed \textit{et al.} to construct linear characteristics presented in this work. Our attacks extend to all variants of SIMON covering more number of rounds compared to the previous results on linear cryptanalysis. We have implemented our attacks for small scale variants of SIMON and our experiments confirm the theoretical bias of various characteristics presented in this work. %We also verified the results for SIMON32/64 experimentally to see whether implementation confirms theory. So far, our results are the best known with respect to linear cryptanalysis for any variant of SIMON

Linear cryptanalysis of pseudorandom functions

Relatório de projeto de pesquisa.In this paper, we study linear relations propagating across block ciphers from the key input to the ciphertext (for a fixed plaintext block). This is a usual setting of a one-way function, used for instance in modes of operation such as KFB (key feedback). We instantiate the block cipher with the full 16-round DES and $s^2$-DES, 10-round LOKI91 and 24-round Khufu, for which linear relations with high bias are well known. Other interesting targets include the full 8.5-round IDEA and PES ciphers for which high bias linear relations exist under the assumption of weak keys. Consequences of these findings impact the security of modes of operation such as KFB and of pseudorandom number/bit generators. These analyses were possible due to the linear structure and the poor diffusion of the key schedule algorithms. These findings shall motivate carefull (re)design of current and future key schedule algorithms

A Security Analysis of IoT Encryption: Side-channel Cube Attack on Simeck32/64

Simeck, a lightweight block cipher has been proposed to be one of the encryption that can be employed in the Internet of Things (IoT) applications. Therefore, this paper presents the security of the Simeck32/64 block cipher against side-channel cube attack. We exhibit our attack against Simeck32/64 using the Hamming weight leakage assumption to extract linearly independent equations in key bits. We have been able to find 32 linearly independent equations in 32 key variables by only considering the second bit from the LSB of the Hamming weight leakage of the internal state on the fourth round of the cipher. This enables our attack to improve previous attacks on Simeck32/64 within side-channel attack model with better time and data complexity of 2^35 and 2^11.29 respectively.Comment: 12 pages, 6 figures, 4 tables, International Journal of Computer Networks & Communication