Substitution Cipher Research Articles

Text Encryption with Graph Theory Based Key Generation

This work presents a new encryption technique that ensures safe communication through two distinct phases: utilizing monoalphabetic substitution ciphers that rely on agreed-upon character-swapping arrangements between authorized individuals and applying an alphabetical encryption table. In addition, the research utilizes the Kurskal technique to calculate the minimum spanning tree, which improves security by creating intricate encrypted text using a shared key based on ideas drawn from graph theory.

Covert 19th century political intrigues of Tenerife nobility revealed by cryptanalyzing an encrypted letter

This article presents a cryptanalysis of a 19th-century encrypted manuscript discovered in the archives of Conde de Siete Fuentes in Tenerife, Canary Islands, Spain. The manuscript, preserved by the heirs of the 6th Count of Valle de Salazar, utilizes a polyalphabetic substitution cipher. The cryptanalysis was performed by applying statistical frequency analysis and developing a Python script for decryption, resulting in the authors successfully deciphering the message. The decrypted letter reveals political communications discussing the strategic positioning of Tenerife as the capital, the dissolution of local councils, and the influence of key political figures. The analysis compares the cipher with historical encryption techniques, and identifies the unique characteristics of the manuscript’s encryption method. The study highlights the political dynamics and alliances within Tenerife’s nobility and their interactions with the central Spanish government, providing significant insights into, both, the cryptographic practices and political maneuvers of the time.

The Condenser PBJ cipher machine

Condenser PBJ is a mechanical cipher machine developed by Pavel Baráček-Jacquier (1885-1969). It was created between 1922 and 1924, and was used by the Czechoslovak diplomatic service until 1934. The machine was designed to be used as a tool for condensing telegraphic messages in a similar way to a codebook, but with encryption added to the result. The encryption algorithm is a polyalphabetic substitution cipher—an autokey cipher with a priming key of length 10. This autokey cipher is different however from the classical Vigenère autokey cipher. We have been able to fully reconstruct the encryption algorithm. We also present a detailed description of the machine, and point out some weaknesses in the cipher’s design.

A Survey on the Advanced Encryption Standard (AES): A Pillar of Modern Cryptography

As the digital landscape expands and our reliance on secure data transmission grows, the adoption of encryption technologies has become paramount. Over time, we have witnessed a progression from rudimentary ciphering methods, like substitution ciphers, to the sophisticated algorithms of today, epitomized by the Advanced Encryption Standard (AES). AES’s ascendancy to the forefront of encryption can be attributed to its unparalleled security features, surpassing its predecessors such as the Data Encryption Standard (DES). AES boasts robust security measures, rendering it virtually impervious to conventional cryptographic attacks. Its resilience against decryption is underscored by its intricate encryption process, which involves intricate operations such as byte substitution, row shifting, column mixing and round key addition. Conversely, decryption reverses these steps, ensuring the confidentiality of encrypted data remains intact. Despite the emergence of various cryptographic attacks, none have posed a significant threat to a properly implemented Full-AES algorithm. Most attacks target incomplete implementations, highlighting the importance of proper implementation practices in maximizing AES’s security benefits. Beyond its security prowess, AES stands out for its efficiency, sustainability and simplicity. Despite its widespread adoption and robustness against cryptanalytic attacks, AES exhibits an intriguing phenomenon known as error propagation. Through theoretical analysis and empirical investigations, we elucidate the mechanisms by which errors propagate within AES, shedding light on the vulnerabilities they introduce. Additionally, we explore the implications of error propagation in practical scenarios, including its impact on cryptographic protocols, error correction mechanisms and overall system reliability. Our findings underscore the importance of comprehensively understanding and mitigating the effects of error propagation in AES implementations, offering insights into enhancing the resilience of cryptographic systems against unforeseen adversities.

Cryptoanalysis of Simple Substitution Ciphers with Genetic Algorithms

Cryptoanalysis of Simple Substitution Ciphers with Genetic Algorithms

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.

Dorabella unMASCed – the Dorabella Cipher is not an English or Latin Mono-Alphabetical Substitution Cipher

The Dorabella cipher is an unsolved cipher with only 87 characters. In this study we show that state-of-the-art algorithms are able to solve Mono-Alphabetical Substitution Ciphers with 87 characters with a decipher rate of up to 98.7% for English and 98.6% for Latin. The same algorithms fail to find a solution to the Dorabella cipher. Furthermore, we consider simple permutations of the Dorabella cipher and attempt to solve the cipher after these are applied, but with no success. This indicates that the Dorabella cipher is unlikely to be a MASC.

SBAC: Substitution cipher access control based on blockchain for protecting personal data in metaverse

The evolution of the metaverse necessitates inventive solutions that can uphold data security. In this paper, we present a novel approach that seamlessly integrates blockchain and substitution cipher techniques to enhance the security landscape of the metaverse. The proposed approach encompasses the generation of the rule table for substitution encryption and decryption, as well as a methodology for data encryption and decryption utilizing the rule table. Furthermore, we conducted a comprehensive evaluation of the proposed approach’s security robustness, especially focusing on its resistance against potential security attacks, including the brute-force attack. Moreover, a series of performance experiments were meticulously conducted to comprehensively gauge the effectiveness and efficiency of the proposed technique. The findings revealed that the proposed approach outperforms asymmetric key algorithms in terms of encryption elapsed time. Additionally, the decryption process of the proposed approach is notably faster than both symmetric and asymmetric key algorithms. The results of security analysis and performance evaluations underscore the viability and efficiency of the proposed approach, positioning it as a promising solution for secure and swift data management within the metaverse environment.

SCMD suspicious cryptographic message detection

The proposed framework aims to prevent global crimes, specifically terrorist attacks, bomb blasts, and drone attacks, by using the Suspicious Cryptographic Message Detection (SCMD) system to detect and decrypt suspicious messages. Terrorists often use encrypted messages to communicate with their teammates in different parts of the world, making it difficult for authorities to monitor their activities. The framework addresses this issue by detecting with gradient boosting algorithm and cryptanalyzing by using Simple Substitution Cipher techniques to decrypt suspicious messages and predict potential criminal activity. The framework utilizes various emerging trends in information technology, including machine learning techniques, pre-defined decision rules, wordnet, and semantic web ontology, to predict the type of crime, the criminal's name and location, and other criminal details. It comprises multiple components, including Semantic web Ontology, Suspicious Database, and machine learning techniques, to facilitate the detection and reporting of criminal activity. When the server receives a suspicious encrypted message, the framework detect and decrypts it and predicts the type of crime based on microblogs before it can be executed by the criminals. The details of the criminals are then alerted to the cybercrime department, reducing the burden on security departments and enhancing public safety. In summary, the framework provides a comprehensive solution to the challenges posed by encrypted messages in criminal activities. It uses advanced technologies to identify and predict potential criminal activities, enabling law enforcement agencies to take preemptive actions to prevent major and minor attacks, including terrorist attacks.

Secured personal notes using face recognition-based decryption

Data are kept in our local database and used by the Android Note program. The data for this project was stored in a cloud database, and anyone with the necessary login information can view the data from any device. The data is encrypted using a monoalphabetic substitution cipher encryption method, which is also used for decryption, to increase security. However, the decryption process adds an extra layer of security with the aid of a machine learning model. The program requests that the user's face be recognized in order to the data decrypted; otherwise, data cannot be decrypted. Cloud-based info will be encrypted and kept safe.

Basic Cryptographic Concepts and Open Problems in Hash Function Security

JOHNNA SMITH, Dept of Mathematics, Shepherd University, Shepherdstown, WV, 25443, and DONALD MILLS, Dept of Computer Sciences, Mathematics, and Engineering, Shepherd University, Shepherdstown, WV, 25443. Analysis of basic cryptographic concepts and recent open problems in hash function security. 
 
 The objectives of this study are to show an understanding of cryptographic concepts as well as highlight recent open problems involving hash function security. The method of study used included reading the first five chapters of Cryptography: Theory and Practice by Stinson and Paterson as well as a recent paper that outlined open problems in hash function security. Then, written reports were delivered on the information learned which included selected proofs and solved examples. The essentials of the opening report introduce the basic elements of cryptography: cryptosystems, cryptographic tools, message integrity, protocols, and security approaches. Chapter 2 of “Cryptography” describes various types of ciphers including Shift, Substitution, Affine, Vigenère, Hill, Permutation, and Stream Ciphers, as well as how to cryptanalyze them. The third report focuses on the One-time Pad, entropy, perfect security, and cryptographic security, specifically unconditional security, as introduced by Claude Shannon in his work on information theory. Throughout the fourth report, block and stream ciphers, including substitution-permutation networks, attacks such as linear and differential cryptanalysis, and modes of operation are discussed. In the fifth report, basic concepts of cryptography, hash function and message authentication are discussed, including iterated hash function, sponge construction, and unconditionally secure MACS. Using the information learned from the previous reports, current problems in hash functions were then researched. In conclusion, open problems in hash function security include collision resistance, preimage resistance, and resistant to length extension attacks. The project was sponsored by the NSF S-STEM Grant (DUE-2130267).

Superposition as a Means of Data Encryption in N-Dimensional Value Spaces

The objective of this study was to provide a new method for creating quantum-proof encryption algorithms. I accomplished this by designing a symmetric 2-key cryptosystem that exploits the superposition principle to encrypt data in multi-dimensional value spaces.
 The proposed cryptosystem substitutes characters for frequencies, as determined by two private keys: component wave order key (CWOK) and character transmission order key (CTOK). A CWOK defines the values and theoretical spatial arrangement of frequencies in a complex wave. A CTOK defines the unique arrangement of system characters (i.e., characters in an encoding scheme such as ASCII), determined by a hash function, to identify a user. Combining the CWOK and CTOK, we construct a character-lookup table (CLT), which defines the character-frequency relationships used to generate a substitution cipher. A cipher’s frequency values must be superimposed in accordance with the CWOK. Fast Fourier Transforms are used during the decryption stage to perform complex wave analysis.
 Complex waves can have n! frequency configurations, where n = the number of component frequencies; each CTOK can have a! character configurations, where a = the number of characters defined in an encoding scheme. Therefore, by requiring n ≥128 and using the ASCII encoding scheme (a = 128), there are n!+a!=128!+128!=2*128! possible key configurations for any given cipher. This is approximately 3.330284e+138 times as many key configurations possible with AES 256.
 Exploiting the multi-dimensional nature of complex waves, and combining these techniques with other powerful encryption algorithms used today, it appears likely that we can create a quantum-proof cryptosystem.

Attacks on the simple substitution cipher with the calculation of their reliability

The historical simple substitution cipher is widely known. In educational literature, the study of ciphers and attacks on them begins with it. Calculation of the complexity of attacks on a simple substitution cipher is usually ignored due to the simplicity of the implementation of these attacks. The question why there are no results on the assessment of the reliability of such attacks (the probability of achieving the goal of the task) remains open. From the practice of carrying out attacks on this cipher, it is believed that knowledge of 25–27 ciphertext characters is sufficient for the English and Russian languages. Claude Shannon proved this fact using the entropy per message letter he calculated. This article proposes a modernization of the ideas embodied in well-known attacks, which makes it possible to calculate the probability of correctly determining the plaintext of a simple substitution cipher using a known ciphertext.

The Scope of Application of Letter Frequency Analysis in Substitution Cipher

Since its inception, substitution ciphers have been a popular type of cipher, and over time, academics have studied them in an effort to discover patterns that will allow them to be broken. They created it because substitution ciphers are a reasonably simple type of cipher. Through a survey of the literature, this paper investigates the encryption and decryption of three sub-types of monoalphabetic ciphers: shift cipher, affine cipher, and random substitution cipher. Letter frequency analysis is the foundation of the primary decryption technique. After that, two sub-kinds of monoalphabetic ciphers, Hill cipher and Playfair cipher, which are resistant to this decryption method because the letters encrypted hardly keep the original frequency, will be introduced. The paper shows that statistical analysis of letter frequency is only useful for deciphering single-table substitution ciphers.

Automated Transcription of Historical Encrypted Manuscripts

Abstract This paper deals with historical encrypted manuscripts and introduces an automated method for the detection and transcription of ciphertext symbols for subsequent cryptanalysis. Our database contains documents used in the past by aristocratic families living in the territory of Slovakia. They are encrypted using a nomenclator which is a specific type of substitution cipher. In our case, the nomenclator uses digits as ciphertext symbols. We have proposed a method for the detection, classification, and transcription of handwritten digits from the original documents. Our method is based on Mask R-CNN which is a deep convolutional neural network for instance segmentation. Mask R-CNN was trained on a manually collected database of digit annotations. We employ a specific strategy where the input image is first divided into small blocks. The image blocks are then passed to Mask R-CNN to obtain detections. This way we avoid problems related to the detection of a large number of small dense objects in a high-resolution image. Experiments have shown promising detection performance for all digit types with minimum false detections.

A Secured Framework for Short Messages Service in Global System for Mobile Communication

Short Message Service (SMS) has upgraded and elevated our lives and is principal in our livelihood. This service has been driven by the Global System for Mobile Communications (GSM) which is the most popular standard for mobile telephony systems. As a result, the GSM has constituted the moderate execution of short message service (SMS), which has uplifted mobile phone quality. A proper understanding of the essentials of SMS/MMS security opens the door to prevent some common security. which has fostered the prevention of some common threats in SMS usage. Unfortunately, the SMS does not has any built-in vetting procedure to authenticate the text or provide security for the data/text, and supportive phone facilities are designed without considering the SMS/MMS security aspects. There is also a problem of mobile applications developer and the mobile service providers not knowing the correct identities of the communicating parties, and also the problem of little to no SMS/MMS content confidentiality and integrity during data transmission. This paper is aimed at addressing these problems by focusing on the use of substitution techniques of audio steganography. We achieve our method by having a low robustness against attacks which try to reveal the hidden message. This allows only SMS that is encrypted, and application to multimedia messages needs to be further investigated. Furthermore, encryption is done using substitution cipher methods. We also analyze the security mechanism based on the mobile security requirements and mobile performance capability. Analysis of the security mechanism based on the mobile security requirements and mobile performance capability is carried out. After an exhaustive computer simulation, the performance of the proposed method is confirmed. The result obtained showed that compression ratio achieved is within the range of 0.1 and 0.5, the best achieved so far.

A treatise on the Rilke cryptogram

The ‘Rilke Cryptogram’ is a possible cipher of German, WWII origin. This study summarises the text’s history, and examines explanations for its nature. Statistical techniques are applied to an updated transcription. The text consists of 18,760 characters in 3,305 unique groups of four, arranged into 670 rows by seven columns on 33 pages of an otherwise ordinary book. The distribution of these groups is not particularly Zipfian, suggesting the text is likely not a code or monoalphabetic substitution cipher. Its alphabet is longer than English and German (46 characters). Character and N-gram entropy analyses suggest the text is less ordered than English and German, but more ordered than random text. Machine-learning modelling suggests the text is a substitution cipher, but frequency and Kasiski-Kerckhoff analyses suggest otherwise. Sukhotin’s algorithm results for the text are somewhat consistent with results for German, though N-gram distributions do not strongly resemble English or German. Statistical analysis of physical typewriter key distances suggest the text’s groupings are highly unlikely to appear at random, and are consistent with intentional ‘lazy’ typing. The text is inconsistent with machine ciphers of its era (e.g., Enigma), and other features are not entirely consistent with non-cipher explanations. Further investigation is required.

Construction and Analysis of Models of Increasing Reliability for Modular Encryption Algorithm

This paper describes the development of a model of symmetric block encryption algorithm using nonpositional polynomial notation systems. Computer model this algorithm was created and its properties were investigated. In order to increase the cryptostrength of the algorithm simple substitution and gamming cipher modes were used, methods of the application of these modes are shown. As a continuation of this work, a computer model for managing keys in the encryption algorithm is being developed

LPsec: a fast and secure cryptographic system for optical connections

High capacity and low latency of optical connections are ideal for supporting current and future communication services, including 5G and beyond. Although some of those services are already secured at the packet layer using standard stream ciphers, like the Advanced Encryption Standard and ChaCha, secure transmission at the optical layer is still not implemented. To secure the optical layer, cryptographic methods need to be fast enough to support high-speed optical transmission and cannot introduce significant delay. Moreover, methods for key exchange, key generation, and key expansion are required, which can be implemented on standard coherent transponders. In this paper, we propose Light Path SECurity (LPsec), a secure cryptographic solution for optical connections that involves fast data encryption using stream ciphers and key exchange using Diffie–Hellman protocol through the optical channel. To support encryption of high-speed data streams, a fast, general-purpose pseudorandom number generator is used. Moreover, to make the scheme more secure against exhaustive search attacks, an additional substitution cipher is proposed. In contrast to the limited encryption speeds that standard stream ciphers can support, LPsec can support high-speed rates. Numerical simulation for 16 quadrature amplitude modulation (QAM), 32-QAM, and 64-QAM show that LPsec provides a sufficient security level while introducing only negligible delay.

A Proposed Method for Achieving the Confidentiality of Arabic Texts

Due to the rapid development of distributed computing systems, the use of local networks, and the huge expansion of the Internet, the process of maintaining the confidentiality of information becomes important and necessary. Encryption is one of the most important ways to keep information confidential and to prevent unauthorized people from disclosing this information. Many cryptographic algorithms have appeared in different ways and methods. But most of these algorithms have been devoted for encrypting texts in the English language. Because of the increasing important and sensitive information exchange in the Arabic language by users on the Internet, an urgent need has appeared to build dedicated encryption systems for the Arabic language. The aim of this research is to provide a proposed encryption method that uses the idea of combining the methods of transposition and substitution cipher for the purpose of Arabic texts confidentiality. This research depends on using diacritics in the Arabic language to perform the process of substitution cipher. The efficiency of the proposed method has been tested on different texts; the method provides high speed execution, the length of the encrypted texts is almost close to the clear text length, and the confidentiality of the resulting encrypted texts is high.