Class Of Ciphers Research Articles

Improved 2-round collision attack on IoT hash standard ASCON-HASH

Lightweight cryptography algorithms are a class of ciphers designed to protect data generated and transmitted by the Internet of Things. They typically have low requirements in terms of storage space and power consumption, and are well-suited for resource-limited application scenarios such as embedded systems, actuators, and sensors. The NIST-approved competition for lightweight cryptography aims to identify lightweight cryptographic algorithms that can serve as standards. Its objective is to enhance data security in various scenarios. Among the chosen standards for lightweight cryptography, ASCON has been selected. ASCON-HASH is a hash function within the ASCON family. This paper presents a detailed analysis of the differential characteristics of ASCON-HASH, utilizing the quadratic S-box. Additionally, we employ message modification techniques and ultimately demonstrate a non-practical collision attack on the 2-round ASCON-HASH, requiring a time complexity of 298 hash function calls.

Historical research on classification of Classical Cryptography

Cryptography is now being applied frequently in peoples daily lives. Their bank passcode, computer password, and digital signature all are applications of cryptography. Inside cryptography, Classical Cipher is a basic and important area as modern cryptography is developed from Classical Cryptography. By making a consummate system of Classical Cryptography, it increases peoples interest in exploring basic cryptography principles. This essay focuses mainly on the topic of classification of Classical Cipher. By reading related materials like books, journals, magazines and so on, the historical research came out the conclusion as the Classical Cipher can be classified as Substitution Cipher, Polyalphabetic Substitution Cipher, and Transposition Cipher. In each class, the essay mentioned several cipher examples, how they encrypt and decrypt the text, and how they can be broken. Caesar Cipher, Simple Substitution Cipher are examples of Substitution Cipher. Vigenere Cipher is mainly discussed inside the Polyalphabetic Substitution Cipher section. In Transposition Cipher part, Scytale and Rail Fence Cipher are listed to demonstrate traits of the Transposition Cipher.

Automated Classical Cipher Emulation Attacks via Unified Unsupervised Generative Adversarial Networks

Cryptanalysis has been studied and gradually improved with the evolution of cryptosystems over past decades. Recently, deep learning (DL) has started to be used in cryptanalysis to attack digital cryptosystems. As computing power keeps growing, deploying DL-based cryptanalysis becomes feasible in practice. However, since these studies can analyze only one cipher type for one DL model learning, it takes a lot of time to analyze multi ciphers. In this paper, we propose a unified cipher generative adversarial network (UC-GAN), which can perform ciphertext-to-plaintext translations among multiple domains (ciphers) using only a single DL model. In particular, the proposed model is based on unified unsupervised DL for the analysis of classical substitutional ciphers. Simulation results have indicated the feasibility and good performance of the proposed approach. In addition, we compared our experimental results with the findings of conditional GAN, where plaintext and ciphertext pairs in only the single domain are given as training data, and with CipherGAN, which is cipher mapping between unpaired ciphertext and plaintext in the single domain, respectively. The proposed model showed more than 97% accuracy by learning only data without prior knowledge of three substitutional ciphers. These findings could open a new possibility for simultaneously cracking various block ciphers, which has a great impact on the field of cryptography. To the best of our knowledge, this is the first study of the cryptanalysis of multiple cipher algorithms using only a single DL model

Quantum Algorithm for the Invariant Estimate of the Closeness of Classical Ciphers to the One-Time Pad

Quantum Algorithm for the Invariant Estimate of the Closeness of Classical Ciphers to the One-Time Pad

Quantum statistical mechanics of encryption: Reaching the speed limit of classical block ciphers

We cast encryption via classical block ciphers in terms of operator spreading in a dual space of Pauli strings, a formulation which allows us to characterize classical ciphers by using tools well known in the analysis of quantum many-body systems. We connect plaintext and ciphertext attacks to out-of-time order correlators (OTOCs) and quantify the quality of ciphers using measures of delocalization in string space such as participation ratios and corresponding entropies obtained from the wave function amplitudes in string space. In particular, we show that in Feistel ciphers the entropy saturates its bound to exponential precision for ciphers with 4 or more rounds, consistent with the classic Luby–Rackoff result that it takes these many rounds to generate strong pseudorandom permutations. The saturation of the string-space information entropy and the vanishing of the OTOCs to exponential precision are taken as necessary conditions for the security of the cipher — we conjecture these criteria are also sufficient, as physically they signal irreversibility and chaos. We argue that the conditions on both OTOCs and string entropies can be satisfied by n-bit block ciphers implemented via random reversible circuits with O(nlogn) gates. This paper focuses on a tree-structured cipher composed of layers of n/3 3-bit gates, for which a “key” specifies uniquely the sequence of gates that comprise the circuit. We show that in order to reach this “speed limit” one must employ a three-stage circuit consisting of a nonlinear stage implemented by layers of nonlinear gates that proliferate the number of strings, flanked by two linear stages, each deploying layers of a special set of linear “inflationary” gates that accelerate the growth of small individual strings. The close formal correspondence to quantum scramblers established in this work leads us to suggest that this three-stage construction is also required in order to scramble quantum states to similar precision and with circuits of similar size. A shallow, O(logn)-depth cipher of the type described here can be used in constructing a polynomial-overhead scheme for computation on encrypted data proposed in another publication as an alternative to Homomorphic Encryption.

A Cryptosystem of Skewed Affine Cipher of Multiple Keys

In this era, where communication over technology has become vital, the reliability of the same is of utmost need. Cryptography ensures confidentiality, user authentication, and integrity of data. One of the techniques is the Elliptic Curve Cryptography (ECC). Several classical ciphers are designed based on mathematical backgrounds. In this paper, we focus on combining Affine Cipher and ECC to magnify the security provided by an Affine cipher. Hence a skewed Affine cipher that uses multiple keys over Elliptic curves is proposed. The keys chosen are derived from the points on the specified Elliptic curve, which forms a cyclic group or a cyclic subgroup.

A Deep Bidirectional LSTM-GRU Network Model for Automated Ciphertext Classification

Long Short-Term Memory (LSTM) and Gated Recurrent Units (GRU) are a class of Recurrent Neural Networks (RNN) suitable for sequential data processing. Bidirectional LSTM (BLSTM) enables a better understanding of context by learning the future time steps in a bidirectional manner. Moreover, GRU deploys reset and update gates in the hidden layer, which is computationally more efficient than a conventional LSTM. This paper proposes an efficient network model based on deep BLSTM-GRU for ciphertext classification aiming to mark the category to which the ciphertext belongs. The proposed model performance was evaluated using well-known evaluation metrics on two publicly available datasets encrypted with various classical cipher methods and performance was compared against one-dimensional convolutional neural network (1D-CNN) and various other deep learning-based approaches. The experimental results showed that the BLSTM-GRU cell unit network model achieved a high classification accuracy of up to 95.8%. To the best of our knowledge, this is the first time an RNN-based model has been applied for the ciphertext classification.

A CRYPTO SYSTEM USING VIGENERE AND POLYBIUS CIPHER

The Cryptography is a Greek word which implies the craft of ensuring data by changing it into a muddled organization and unreadable format. Cryptography is a method to secure sensitive data for storage and communication in the presence of third parties called adversaries. It is a mix of arithmetic and software engineering. The drastic growth of the Internet over a period of time made an unintentional security. Even though security is the measure worries over the internet, numerous applications have been created and structured without considering fundamental destinations of data security that is confidentiality, authentication, and protection. To gain some undesirable clients or individuals to gain admittance to the data, cryptography is required. This paper introduces a new hybrid security cipher by combining the two most important Ciphers such as Polybius Cipher and Vigenere Cipher. This hybrid encryption cipher provides greater security as compared to classic ciphers.

Implementasi Algoritma Kriptografi Playfair Cipher untuk Mengamankan Data Aset

Data sangatlah penting untuk manusia, data juga dibutuhkan untuk mengumpulkan informasi. Namun mengingat kejahatan cybercrime sudah banyak terjadi di era digital saat ini. Oleh karena itu, keamanan data menjadi hal yang sangat penting untuk diperhatikan. Didalam perusahaan mempunyai data penting. Salah satunya perusahaan di Karawang yaitu PT Adyawinsa Stamping Industries terdapat aplikasi penginputan data yaitu data aset perusahaan. Banyaknya masalah kejahatan data membuat sistem basis data rentan untuk dimanipulasi. Oleh sebab itu, dilakukan implementasi keamanan data terhadap data aset dengan menggunakan kriptografi Playfair Cipher. Playfair Cipher ini mengenkripsikan pasangan huruf (bigram atau digraf) menjadi pasangan huruf, bukan huruf tunggal seperti pada cipher klasik lainnya. Tujuan penelitian ini adalah aplikasi yang mampu melakukan enkripsi data dengan menggunakan algoritma kriptografi Playfair Cipher dan aplikasi juga mampu melakukan dekripsi dari data di dalam database telah dienkripsi kemudian memasukkan data yang telah dienkripsi ke dalam database Hasil dari penelitian ini menunjukkan bahwa sistem yang dibangun telah berhasil melakukan enkripsi dan dekripsi data aset terhadap nama user dan nama aset dengan menggunakan algoritma kriptografi Playfair Cipher. Terdapat perbedaan hasil dekripsi yang diuji dalam penelitian ini. Akan tetapi, aplikasi dapat mengatur hasil dekripsi dengan tools yang terdapat di dalam aplikasi.

A Novel Dynamic Attack on Classical Ciphers Using an Attention-Based LSTM Encoder-Decoder Model

Information security has become an intrinsic part of data communication. Cryptanalysis using deep learning–based methods to identify weaknesses in ciphers has not been thoroughly studied. Recently, long short-term memory (LSTM) networks have shown promising performance in sequential data processing by modeling the dependencies and data dynamics. Given an encrypted ciphertext sequence and corresponding plaintext, by taking advantage of sequential processing, LSTM can adaptively discover the decryption function regardless of the complexity level, which substantially outperforms traditional methods. However, a lengthy ciphertext sequence causes LSTM to lose important information along the sequence, leading to a decrease in network performance. To tackle these problems, we propose adding an attention mechanism to enhance the LSTM sequential processing power. This paper presents a novel, dynamic way to attack classical ciphers by using an attention-based LSTM encoder-decoder for different ciphertext sequence lengths. The proposed approach takes in a sequence of ciphertext and outputs a sequence of plaintext. The effectiveness and flexibility of the proposed model were evaluated on different classical ciphers. We got close to 100% accuracy in breaking all types of classical ciphers in character-level and word-level attacks. We empirically provide further insights into our results on two datasets with short and long ciphertext lengths. In addition, we provide a performance comparison of the proposed method against state-of-the-art methods. The proposed approach has the potential to attack modern ciphers. To the best of our knowledge, this is the first time an attention-based LSTM encoder-decoder has been applied to attack classical ciphers.

Quantum Stream Ciphers: Impossibility of Unconditionally Strong Algorithms

Stream ciphers form one of two large classes of ciphers with private keys in classical cryptography. In this paper, we introduce the concept of a quantum stream cipher. Special types of quantum stream ciphers were proposed earlier by numerous researchers. We prove a general result on the nonexistence of an unconditionally strong quantum stream cipher if the length of a message is much longer than the length of a key. We analyze individual and collective attacks against a quantum stream cipher. A relationship between the problem of guessing the key by the opponent and the problem of distinguishing of random quantum states is established.

Outer-Convex Dominating Set in the Corona of Graphs as Encryption Key Generator

In this paper, we present a new type of symmetric encryption by converting the classical monoalphabetic affine cipher into a polyalphabetic cipher. The proposed encryption utilizes the properties of outer-convex dominating set in the corona of graphs to generate random keys from the shared keyword to every character of the message. The new encryption eliminates the weaknesses of affine cipher, thus increasing the level of confidence for exchanging messages.

New Mathblocks-Based Feistel-Like Ciphers for Creating Clone-Resistant FPGA Devices

The Secret Unknown Cipher (SUC) concept was introduced a decade ago as a promising technique for creating pure digital clone-resistant electronic units as alternatives to the traditional non-consistent Physical Unclonable Functions (PUFs). In this work, a very special unconventional cipher design is presented. The design uses hard-core FPGA (Field Programmable Gate Arrays) -Mathblocks available in modern system-on-chip (SoC) FPGAs. Such Mathblocks are often not completely used in many FPGA applications; therefore, it seems wise to make use of such dead (unused) modules to fabricate usable physical security functions for free. Standard cipher designs usually avoid deploying multipliers in the cipher mapping functions due to their high complexity. The main target of this work is to design large cipher classes (e.g., cipher class size >2600) by mainly deploying the FPGA specific mathematical cores. The proposed cipher designs are novel hardware-oriented and new in the public literature, using fully new unusual mapping functions. If a random unknown selection of one cipher out of 2600 ciphers is self-configured in a device, then a Secret Unknown Cipher module is created within a device, making it physically hard to clone. We consider the cipher module for free (for zero cost) if the major elements in the cipher module are making use of unused reanimated Mathblocks. Such ciphers are usable in many future mass products for protecting vehicular units against cloning and modeling attacks. The required self-reconfigurable devices for that concept are not available now; however, they are expected to emerge in the near future.

Classification and Identification of Classical Cipher Type using Artificial Neural Networks

In this paper, the capability of classifying the main types of classical ciphers systems is presented using Artificial Neural Networks (ANNs) starting from simplest form of information (natural text) and ending with more complex type of classical ciphers (periodic polyalphabetic system and polygraph system with four degrees of key order). The aim of this paper is to prove that all classical ciphers can be classified or identified depending on the degree of complexity of the ciphertext. This can be done by using three levels of classification. The obtained results showed that the proposed classifier can successfully classify the classical cipher systems. This is a clear success for the proposed classifier opening further research directions and can produce informative insights on the problem of identifying and classification of ciphertext produced by modern ciphers, which is an important activity in automated cryptanalysis.

Cryptanalysis of the Columnar Transposition Using Meta-Heuristics

Abstract The most commonly used methods for solving classical (historical) ciphers are based on global optimization (meta-heuristic methods). Despite the fact that global optimization is a well-studied problem, in the case of classical ciphers, there are still many open questions such as the construction of fitness functions or efficient transformation of the cryptanalysis (breaking attempt) to an optimization problem. Therefore the transformation of a cryptanalytical task to an optimization problem and the choice of a suitable fitness function form an important part of the topic. In this paper, we focus on the simple columnar transposition in depth. Our main contribution is a detailed analysis and comparison of different fitness functions, fitness landscape analysis and solving experiments.

An Improved Genetic Algorithm and A New Discrete Cuckoo Algorithm for Solving the Classical Substitution Cipher

Searching secret key of classical ciphers in the keyspace is a challenging NP-complete problem that can be successfully solved using metaheuristic techniques. This article proposes two metaheuristic techniques: improved genetic algorithm (IGA) and a new discrete cuckoo search (CS) algorithm for solving a classical substitution cipher. The efficiency and effectiveness of the proposed techniques are compared to the existing tabu search (TS) and genetic algorithm (GA) techniques using three criteria: (a) average number of key elements correctly detected, (b) average number of keys examined before determining the required key, and (c) the mean performance time. As per the results obtained, the improved GA is comparatively better than the existing GA for criteria (a) and (c), while the proposed CS strategy is significantly better than rest of the algorithms (i.e., GA, IGA, and TS) for all three criteria. The obtained results indicate that the proposed CS technique can be an efficient and effective option for solving other similar NP-complete combinatorial problems also.

Cryptanalysis of MRVLK Using Genetic Algorithm

Classical block ciphers do not show high performance confronting with analytical algorithms due to their rigid structure and fixed output. In recent years there is much attention to the encryption algorithms with random structure. One of these algorithms is message-based random variable length key (MRVLK) which has random numbers in its structure to achieve different random key and different random output in different execution. It is claimed that this algorithm is near random oracle model and its key has factorial order. In this article, it is tried to perform a general attack on that algorithm to analyze its weak points. Finally, by taking advantage of these weaknesses, a cipher-text only attack is applied by genetic algorithms to find the plaintext. Proposed method is implemented in Mat-lab software and was successful to find corresponding plaintext. Obtained results indicate that it is more than 80% efficient to find corresponding plaintext. These results can be improved by using other intelligent algorithms.

Classification and Identification of Classical Cipher Type Using Artificial Neural Networks

In this paper, the capability of classifying the main types of classical ciphers systems is presented using Artificial Neural Networks (ANNs) starting from simplest form of information (natural text) and ending with more complex type of classical ciphers (periodic polyalphabetic system and polygraph system with four degrees of key order). The aim of this paper is to prove that all classical ciphers can be classified or identified depending on the degree of complexity of the ciphertext. This can be done by using three levels of classification. The obtained results showed that the proposed classifier can successfully classify the classical cipher systems. This is a clear success for the proposed classifier opening further research directions and can produce informative insights on the problem of identifying and classification of ciphertext produced by modern ciphers, which is an important activity in automated cryptanalysis.

Flatness and structural analysis as a constructive framework for private communication

This paper deals with the use of control theoretical concepts, essentially flatness, along with structural analysis, in the context of private communication. A new and systematic methodology to design a cryptographic architecture belonging to the special class of ciphers called Self Synchronizing Stream Ciphers (SSSC) is proposed. 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 a general framework to design SSSC involving dynamical systems taking the form of switched linear systems over finite fields with arbitrary state transition functions. An example of cipher with complete specifications is given. Its implementation on a small scale breeding of an ICS-SCADA equipment is described.

Cryptanalysis on classical cipher based on Indonesian language

Cryptanalysis is a process of breaking a cipher in an illegal decryption. This paper discusses about encryption some classic cryptography, breaking substitution cipher and stream cipher, and increasing its security. Encryption and ciphering based on Indonesian Language text. Microsoft Word and Microsoft Excel were chosen as ciphering and breaking tools.