The Simon and Speck families of block ciphers were designed specifically to offer security on constrained devices, where simplicity of design is crucial. However, the intended use cases are diverse and demand flexibility in implementation. Simplicity, security, and flexibility are ever-present yet conflicting goals in cryptographic design. This paper outlines how these goals were balanced in the design of Simon and Speck.

The SIMON and SPECK lightweight block ciphers

We propose two systematic methods to describe the differential property of an S-box with linear inequalities based on logical condition modelling and computational geometry respectively. In one method, inequalities are generated according to some conditional differential properties of the S-box; in the other method, inequalities are extracted from the H-representation of the convex hull of all possible differential patterns of the S-box. For the second method, we develop a greedy algorithm for selecting a given number of inequalities from the convex hull. Using these inequalities combined with Mixed-integer Linear Programming (MILP) technique, we propose an automatic method for evaluating the security of bit-oriented block ciphers against the (related-key) differential attack with several techniques for obtaining tighter security bounds, and a new tool for finding (related-key) differential characteristics automatically for bit-oriented block ciphers.

/pdf/automatic-security-evaluation-and-related-key-differential-5erle8kbwv.pdf

Automatic Security Evaluation and (Related-key) Differential Characteristic Search: Application to SIMON, PRESENT, LBlock, DES(L) and Other Bit-Oriented Block Ciphers

The U.S. National Security Agency (NSA) developed the Simon and Speck families of lightweight block ciphers as an aid for securing applications in very constrained environments where AES may not be suitable. This paper summarizes the algorithms, their design rationale, along with current cryptanalysis and implementation results.

/pdf/simon-and-speck-block-ciphers-for-the-internet-of-things-2vkz23sw1g.pdf

SIMON and SPECK: Block Ciphers for the Internet of Things.

This book constitutes the refereed proceedings of the 30th Annual International Conference on the Theory and Applications of Cryptographic Techniques, EUROCRYPT 2011, held in Tallinn, Estonia, in May 2011. The 31 papers, presented together with 2 invited talks, were carefully reviewed and selected from 167 submissions. The papers are organized in topical sections on lattice-base cryptography, implementation and side channels, homomorphic cryptography, signature schemes, information-theoretic cryptography, symmetric key cryptography, attacks and algorithms, secure computation, composability, key dependent message security, and public key encryption.

Advances in cryptology : Eurocrypt 2011 : 30th annual international conference on the theory and applications of cryptographic techniques, Tallinn, Estonia, May 15-19, 2011 : proceedings

In this article, we revisit the design strategy of PRESENT, leveraging all the advances provided by the research community in construction and cryptanalysis since its publication, to push the design up to its limits. We obtain an improved version, named GIFT, that provides a much increased efficiency in all domains (smaller and faster), while correcting the well-known weakness of PRESENT with regards to linear hulls.

GIFT : A Small Present

At CHES 2010, the new block cipher PRINTcipher was presented as a light-weight encryption solution for printable circuits [15]. The best attack to date is a differential attack [1] that breaks less than half of the rounds. In this paper, we will present a new attack called invariant subspace attack that breaks the full cipher for a significant fraction of its keys. This attack can be seen as a weak-key variant of a statistical saturation attack. For such weak keys, a chosen plaintext distinguishing attack can be mounted in unit time. In addition to breaking PRINTcipher, the new attack also gives us new insights into other, more well-established attacks. We derive a truncated differential characteristic with a round-independent but highly key-dependent probability. In addition, we also show that for weak keys, strongly biased linear approximations exists for any number of rounds. In this sense, PRINTcipher behaves very differently to what is usually - often implicitly - assumed.

https://www.iacr.org/archive/crypto2011/68410202/68410202.pdf

A cryptanalysis of PRINTcipher: the invariant subspace attack

Recently, the U.S National Security Agency has published the specications of two families of lightweight block ciphers, SIMON and SPECK, on ePrint (2). The ciphers are developed with optimization towards both hardware and software in mind. While the spec- ication paper discusses design requirements and performance of the presented lightweight ciphers thoroughly, no security assessment is given. This paper is a move towards lling that cryptanalysis gap for the SIMON family of ciphers. We present a series of observations on the presented construction that, in some cases, yield attacks, while in other cases may provide basis of further analysis by the cryptographic community. Specically, we obtain attacks using classical- as well as truncated dierentials. In the former case, we show how the smallest version of SIMON, Simon32/64, exhibits a strong dierential eect.

/pdf/cryptanalysis-of-the-simon-family-of-block-ciphers-1b3t5jr46x.pdf

Cryptanalysis of the SIMON Family of Block Ciphers.

As two important cryptanalytic methods, impossible differential and integral cryptanalysis have attracted much attention in recent years Although relations among other cryptanalytic approaches have been investigated, the link between these two methods has been missing The motivation in this paper is to fix this gap and establish links between impossible differential cryptanalysis and integral cryptanalysis

/pdf/links-among-impossible-differential-integral-and-zero-43ep4nbjss.pdf

Links Among Impossible Differential, Integral and Zero Correlation Linear Cryptanalysis

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 SIMON\({N}/{K}\). 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 the specific SIMON variant. Finally, we exploit a connection between linear and differential characteristics for SIMON to construct linear characteristics for different variants of reduced-round SIMON. Our attacks extend to all variants of SIMON covering more rounds compared to any known results using linear cryptanalysis. We present a key recovery attack against SIMON128/256 which covers 35 out of 72 rounds with data complexity \(2^{123}\). We have implemented our attacks for small scale variants of SIMON and our experiments confirm the theoretical bias presented in this work.

Cryptanalysis of SIMON Variants with Connections

The construction industry has long faced the challenge of introducing collaborative systems among multiple stakeholders. This challenge creates a high level of rigidity in terms of processing shared information related to different processes, robust holistic regulations, payment actualizations, and resource utilization across different nodes. The need for a digital platform to crossconnect all stakeholders is necessary. A blockchain-based platform is a prime candidate to improve the industry in general and the construction supply chain (CSC) in particular. In this paper, a literature review is presented to establish the main challenges that CSC faces in terms of its effects on productivity and efficiency. In addition, the effect of applying blockchain platforms on a case study is presented and analyzed from performance and security level. The analysis aims to emphasize that blockchain, as presented in this paper, is a viable solution to the challenges in the CSC regardless of the risks associated with the security and robustness of the flow of information and data protection. Moreover, a threat analysis of applying a blockchain model on the CSC industry is introduced. This model indicates potential attacks and possible countermeasures to prevent the attacks. Future work is needed to expand, quantify, and optimize the threat model and conduct simulations considering proposed countermeasures for the different blockchain attacks outlined in this study.

Hoda AlKhzaimi

Papers

A cryptanalysis of PRINTcipher: the invariant subspace attack

Cryptanalysis of the SIMON Family of Block Ciphers.

Links Among Impossible Differential, Integral and Zero Correlation Linear Cryptanalysis

Cryptanalysis of SIMON Variants with Connections

Blockchain applied to the construction supply chain: A case study with threat model