Design Of Stream Ciphers Research Articles

An exhaustive review of the stream ciphers and their performance analysis

The number of internet of things (IoT) applications has increased, which has increased the demand for low-resource gadgets. The data produced by these devices must be protected to guarantee security. The devices operate in conditions with limited space, computational power, memory, and energy. High-security standards are difficult to achieve with limited resources. The detailed analysis of various stream ciphers and their performance metrics is reviewed in this manuscript. The functionality of the stream ciphers is categorized and thoroughly discussed based on both the hardware and software viewpoints. The security attacks and their countermeasure methods using stream ciphers are discussed. The performance metrics of most hardware-based stream ciphers, including the ECRYPT stream cipher project (eSTREAM) ciphers, are discussed. Each hardware stream cipher design highlights the hardware constraints such as chip area, frequency, throughput, and hardware efficiency. The work also highlights the various applications using these stream ciphers. The current trends using these stream ciphers are discussed with futuristic goals.

Flatness and structural analysis for the design of stream ciphers involving hybrid automata

This paper deals with hybrid dynamical systems in the context of cybersecurity and Cyber–Physical Systems. It is shown how the design of a cipher, called self-synchronizing stream cipher, can be recast as control-theoretic issues, in particular left inversion, flatness and structural analysis. From an automatic control point of view, the main contribution lies in a methodology to construct generic flat LPV systems. Beyond pure control theoretic matters, the design also addresses computational complexity and security concerns. Those considerations motivate a hybrid architecture involving switched automata. A Proof-Of-Concept example illustrates the design of a statistical self-synchronizing stream cipher and the way how it operates to encrypt data flows.

Design and Analysis of a new Stream Cipher based on Ring FCSR Automaton

Design and Analysis of a new Stream Cipher based on Ring FCSR Automaton

Provable security against generic attacks on stream ciphers

Abstract Recent lightweight hardware-based stream cipher designs keep an external non-volatile internal state that is not part of the cipher’s hardware module. The purpose of these so-called small-state ciphers is to keep the size of the hardware and the power consumption low. We propose a random oracle model for stream ciphers. This will allow us to analyse the recent small-state stream cipher designs’ resistance against generic attacks and, in particular, time-memory-data tradeoff attacks. We analyse the conventional construction underlying stream ciphers like Grain and Trivium, constructions continuously using the external non-volatile secret key during keystream generation like Sprout, Plantlet, Fruit, and Atom, constructions continuously using the external non-volatile IV, and constructions using a combination of the IV and the key like DRACO. We show the tightness of all bounds by first presenting the time-memory-data tradeoff attacks on the respective constructions, establishing the upper bound on security, and then presenting the proof of security to establish the lower bound on security. In this work, we extend the theoretical work done by Hamann et al. who introduced the DRACO stream cipher at FSE 2023. We use the same random oracle model as the aforementioned work and apply it to the earlier work by Hamann et al. presented at SAC 2019, which showed security for two of the four constructions we consider in this work. Our model is equivalent but allows for a much simpler proof of security. Furthermore, we provide a proof of security for stream ciphers continuously using the secret key during keystream generation, giving upper and lower bounds for all four generic stream cipher constructions proposed so far.

Fixed points of the subset sum pseudorandom number generators

We give upper bounds on the power moments of the number of fixed points of a family of subset sum pseudorandom number generators, introduced by Rueppel (Analysis and design of stream ciphers, Springer-Verlag, Berlin, 1986).

A new result on irreducible NFSRs with respect to cascade connection

Nonlinear feedback shift registers (NFSRs) are widely used in stream cipher design as building blocks. The cascade connection of NFSRs, known as an important architecture, has been adopted in Grain family of stream ciphers. In this paper, a new sufficient condition under which an NFSR cannot be decomposed into the cascade connection of two smaller NFSRs is presented, which is easy to be verified from the algebraic normal form (ANF) of the characteristic function. In fact, our results are also applicable to nonsingular Boolean functions, which actually improve a previous research of Rhodes [6] where the characteristic functions of NFSRs cannot be contained.

Atom: A Stream Cipher with Double Key Filter

It has been common knowledge that for a stream cipher to be secure against generic TMD tradeoff attacks, the size of its internal state in bits needs to be at least twice the size of the length of its secret key. In FSE 2015, Armknecht and Mikhalev however proposed the stream cipher Sprout with a Grain-like architecture, whose internal state was equal in size with its secret key and yet resistant against TMD attacks. Although Sprout had other weaknesses, it germinated a sequence of stream cipher designs like Lizard and Plantlet with short internal states. Both these designs have had cryptanalytic results reported against them. In this paper, we propose the stream cipher Atom that has an internal state of 159 bits and offers a security of 128 bits. Atom uses two key filters simultaneously to thwart certain cryptanalytic attacks that have been recently reported against keystream generators. In addition, we found that our design is one of the smallest stream ciphers that offers this security level, and we prove in this paper that Atom resists all the attacks that have been proposed against stream ciphers so far in literature. On the face of it, Atom also builds on the basic structure of the Grain family of stream ciphers. However, we try to prove that by including the additional key filter in the architecture of Atom we can make it immune to all cryptanalytic advances proposed against stream ciphers in recent cryptographic literature.

Applied study on cryptographic functions for algorithms used in communications security protocols

Communications security is one of the most important fields to take into account when designing a system that manages information, especially when implementing such a system for the military, no matter which branch, Navy, Air Force or Army. One important field when talking about information security in general is cryptology and within cryptology linear and nonlinear Boolean functions and maps are essential, important building blocks. They are used in the design of several block and stream ciphers. The study of cryptographic properties of these functions does not only help cryptanalysis but also plays an important role in the design of cryptographic algorithms that resist well against various cryptographic attacks. Linear and differential cryptanalysis of block ciphers is mainly based on determining and exploiting linear combinations of their components. The most useful mathematical tool for studying linearity of Boolean functions is the Walsh (or Hadamard) transform. This can be regarded as a size-2 discrete Fourier transform. Another method for determining linear combinations of cipher components is that of finding and solving linear systems of equations. This article reflects the authors’ effort to shed some light on this field.

Stream cipher designs: a review

Stream cipher is an important branch of symmetric cryptosystems, which takes obvious advantagesin speed and scale of hardware implementation. It is suitable for using in the cases of massive data transfer or resource constraints, and has always been a hot and central research topic in cryptography.With the rapid development of network and communication technology, cipher algorithms play more and more crucial role in information security. Simultaneously, the application environment of cipher algorithms is increasingly complex, which challenges the existing cipher algorithms and calls for novel suitable designs.To accommodate new strict requirements and provide systematic scientific basis for future designs, this paper reviews the development history of stream ciphers, classifies and summarizes the design principles of typical stream ciphers in groups, briefly discusses the advantages and weakness of various stream ciphers in terms of security and implementation. Finally, it tries to foresee the prospective design directions of stream ciphers.

A New Upper Bound on the Order of Affine Sub-families of NFSRs

Nonlinear feedback shift registers (NFSRs) are widely used as building blocks in the design of stream ciphers. Let NFSR(f) be an NFSR with the characteristic function f and let G(f) be the set of output sequences of NFSR(f). For a given NFSR(f), if there exists an affine Boolean function l such that G(l) ⊆ G(f), then G(l) is called an affine sub-family of NFSR(f). In this paper, by skillfully combining previous ideas, the authors give a new upper bound on the order of affine sub-families of NFSR(f). Compared with the four known bounds, the bound is better than three of them, and in some cases is also better than the rest one.

Recent Results on Constructing Boolean Functions with (Potentially) Optimal Algebraic Immunity Based on Decompositions of Finite Fields

Boolean functions with optimal algebraic immunity (OAI functions) are important cryptographic primitives in the design of stream ciphers. During the past decade, a lot of work has been done on constructing such functions, among which mathematics, especially finite fields, play an important role. Notably, the approach based on decompositions of additive or multiplicative groups of finite fields turns out to be a very successful one in constructing OAI functions, where some original ideas are contributed by Tu and Deng (2012), Tang, et al. (2017), and Lou, et al. (2015). Motivated by their pioneering work, the authors and their collaborators have done a series of work, obtaining some more general constructions of OAI functions based on decompositions of finite fields. In this survey article, the authors review our work in this field in the past few years, illustrating the ideas for the step-by-step generalizations of previous constructions and recalling several new observations on a combinatorial conjecture on binary strings known as the Tu-Deng conjecture. In fact, the authors have obtained some variants or more general forms of Tu-Deng conjecture, and the optimal algebraic immunity of certain classes of functions we constructed is based on these conjectures.

Design of Feedback Shift Register of Against Power Analysis Attack

For simple hardware structure, high speed encryption and lower power consuming, stream ciphers well suited for constrained environments, such as satellite communications, RFID tag, sensor networks and IoT. Linear feedback shift register (LFSR) is widely used in the design of stream cipher to improve the periodic property of key stream. Since the switching of the status bits is regular, the power consumption of the LFSR is highly correlated in a linear way. The power consumption characteris-tics of stream cipher based on LFSR are vulnerable to leaking initialization vectors (IV) under the power attacks. Basing on the power model of LFSR, a new design of LFSR against power attacks is proposed in this paper. In this countermeasure, the power consumption characteristics of LFSR can be masked by using an additional LFSR and a new filter Boolean function. Compared with the others designs, this de-sign can confused the power consumption trace and can be more easily implemented by circuits.

Some results on Fruit

In FSE 2015, Armknecht et al. proposed a new technique to design stream ciphers, which involves repeated use of keybits in each round of the keystream bit generation. This technique showed the possibility to design stream ciphers where the internal state size is significantly lower than twice the key size. They proposed a new cipher based on this idea, named Sprout. But soon Sprout was proved to be insecure. In Crypto 2015, Lallemand et al. proposed an attack which was $$2^{10}$$ times faster than the exhaustive search. But the new idea used in Sprout showed a new direction in the design of stream cipher, which led to the proposal of several new ciphers with small size of internal state. Fruit is a recently proposed cipher where both the key size and the state size are 80. In this paper, we attack full round Fruit by a divide-and-conquer method. Our attack is equivalent to $$2^{74.95}$$ many Fruit encryptions, which is around 16.95 times faster than the average exhaustive key search. Our idea also works for the second version of Fruit.

Towards Low Energy Stream Ciphers

Energy optimization is an important design aspect of lightweight cryptography. Since low energy ciphers drain less battery, they are invaluable components of devices that operate on a tight energy budget such as handheld devices or RFID tags. At Asiacrypt 2015, Banik et al. presented the block cipher family Midori which was designed to optimize the energy consumed per encryption and which reduces the energy consumption by more than 30% compared to previous block ciphers. However, if one has to encrypt/decrypt longer streams of data, i.e. for bulk data encryption/decryption, it is expected that a stream cipher should perform even better than block ciphers in terms of energy required to encrypt. In this paper, we address the question of designing low energy stream ciphers. To this end, we analyze for common stream cipher design components their impact on the energy consumption. Based on this, we give arguments why indeed stream ciphers allow for encrypting long data streams with less energy than block ciphers and validate our findings by implementations. Afterwards, we use the analysis results to identify energy minimizing design principles for stream ciphers.

A ring-like cascade connection and a class of NFSRs with the same cycle structures

Nonlinear feedback shift registers (NFSRs) are widely used in stream cipher designs. In this paper, we propose a variant of cascade connections of NFSRs, called ring-like cascade connections. It is...

Fruit-80: A Secure Ultra-Lightweight Stream Cipher for Constrained Environments.

In Fast Software Encryption (FSE) 2015, while presenting a new idea (i.e., the design of stream ciphers with the small internal state by using a secret key, not only in the initialization but also in the keystream generation), Sprout was proposed. Sprout was insecure and an improved version of Sprout was presented in FSE 2017. We introduced Fruit stream cipher informally in 2016 on the web page of IACR (eprint) and few cryptanalysis were published on it. Fortunately, the main structure of Fruit was resistant. Now, Fruit-80 is presented as a final version which is easier to implement and is secure. The size of LFSR and NFSR in Fruit-80 is only 80 bits (for 80-bit security level), while for resistance to the classical time-memory-data tradeoff (TMDTO) attacks, the internal state size should be at least twice that of the security level. To satisfy this rule and to design a concrete cipher, we used some new design ideas. It seems that the bottleneck of designing an ultra-lightweight stream cipher is TMDTO distinguishing attacks. A countermeasure was suggested, and another countermeasure is proposed here. Fruit-80 is better than other small-state stream ciphers in terms of the initialization speed and area size in hardware. It is possible to redesign many of the stream ciphers and achieve significantly smaller area size by using the new idea.

On Design of Robust Lightweight Stream Cipher with Short Internal State

On Design of Robust Lightweight Stream Cipher with Short Internal State

Design and analysis of small-state grain-like stream ciphers

Time-memory-data (TMD) tradeoff attacks limit the security level of many classical stream ciphers to the birthday bound. Very recently, a new field of research has emerged, which searches for so-called small-state stream ciphers that try to overcome this limitation. In this paper, existing designs and known analysis of small-state stream ciphers are revisited and new insights on distinguishers and key recovery are derived based on TMD tradeoff attacks. A particular result is the transfer of a generic distinguishing attack suggested in 2007 by Englund et al. to this new class of lightweight ciphers. Our analysis shows that the initial hope of achieving full security against TMD tradeoff attacks by continuously using the secret key has failed. In particular, we provide generic distinguishers for Plantlet and Fruit with complexity significantly smaller than that of exhaustive key search. However, by studying the assumptions underlying the applicability of these attacks, we are able to come up with a new design idea for small-state stream ciphers, which might allow to finally achieve full security against TMD tradeoff attacks. Another contribution of this paper is the first key recovery attack against the most recent version of Fruit. We show that there are at least 264 weak keys, each of which does not provide 80-bit security as promised by designers.

Mobile Phone Security Based New Strong Genetic Stream Cipher Design

Mobile phones are considered to be the most common communication devices in history. Recently, mobile phones are not only used for communication but also to send and receive important data such as social security numbers, bank account details and passwords. Mobile phone communication uses the encryption algorithms collectively called as A5 family which corresponds to symmetric-key Stream ciphers that generate pseudo-random binary sequences used to encrypt the message signals on bit-by-bit basis. Unfortunately all these algorithms that ensure the security of mobile communications are cryptanalyzed and suffer from several attacks. In this paper, a new genetic pseudo random bit generator (PRBG) based on genetic algorithm is proposed to make mobile phone encryption algorithm A5 robust and resistive to the attacks such as time memory trade off, divide and conquer. A basic security analysis shows that the proposed algorithm is more resistant for cryptanalysis with a good quality of bits stream produced by our generator called genetic A5.

Design of Self-Synchronizing Stream Ciphers: a New Control-Theoretical Paradigm

This paper deals with the use of control theoretical concepts in the context of private communication. It is proposed a new and systematic methodology to design a cryptographic architecture belonging to the special class of ciphers called Self Synchronizing Stream Ciphers (SSSC). Till now, the constructions of SSSC were based on automata with finite input memory involving shifts or triangular functions (T-functions) as state transition functions. Besides, only ad-hoc approaches were available in the literature. The contribution of this paper is to propose not only a general framework to design SSSC, but with potentially more general state transition functions as well. Two control-theoretical issues are treated to this end: as a new paradigm, the construction of flat dynamical systems, and on the other hand, the notion of mortality of a set of matrices, a problem which is in general not decidable.