The Fiat-Shamir: zero(-knowledge) to signature in sixty minutes (of class time)

Digital signature and hash algorithms are essential components of the blockchain. Bitcoin and Ethereum use the same digital signature scheme Elliptic Curve Digital Signature Algorithm (ECDSA). However, they use the different hash algorithms. Bitcoin chooses to use Secure Hash Algorithm (SHA), and Ethereum uses Keccak-256. This paper studies the digital signature ECDSA by looking into its design, implementation and security. ECDSA is a variant of Digital Signature Algorithm (DSA). It requires a shorter key length than Rivest–Shamir–Adleman (RSA), so it was preferred to use in the blockchain. Furthermore, this paper will also explore the design and implementation of SHA-256 and Keccak- 256. Bitcoin chose to use SHA-256 since it came out earlier than Keccak-256 with adequate security. Conversely, Keccak-256 is preferred by Ethereum since it has better performance and security compared to SHA-256. The role of SHA-256 and Keccak-256 in Bitcoin and Ethereum are also explored. SHA-256 and Keccak-256 are used in the blockchains’ proof-of-work (or proof-of-stake) and merkle tree structure. The paper will also look into their security by analyzing the result of possible attacks against them. In addition, the paper will provide some thoughts on the security of ECDSA, SHA-256 and Keccak-256 by analyzing their designs and possible attacks.

Recently, a fast and secure hash function SFHA - 256 has been proposed and claimed as more secure and as having a better performance than the SHA - 256. In this paper an improved version of SFHA - 256 is proposed and analyzed using two parameters, namely the avalanche effect and uniform deviation. The experimental results and further analysis ensures the performance of the newly proposed and improved SFHA-256. From the analysis it can be concluded that the newly proposed algorithm is more secure, efficient, and practical.

In the current landscape where quantum algorithms pose a significant threat to conventional digital signature algorithms, code-based digital signature algorithms have emerged as the primary focus of ongoing research in post-quantum cryptography. Digital signatures play a pivotal role in ensuring non-repudiation and authentication, making them an indispensable cryptographic technique. The vulnerability of most digital signature algorithms to quantum attacks have prompted a significant surge in research on code-based digital signature algorithms, which have emerged as a prominent field within post-quantum cryptography. There are generally three distinct approaches to constructing code-based digital signature algorithms: (1) Developing an algorithm that follows the inverse process of the code-based public-key encryption algorithm; (2) Utilizing zero-knowledge identification algorithms in conjunction with the Fiat–Shamir paradigm to formulate a signature algorithm; (3) Constructing a specialized subset of the syndrome space as the foundation for the digital signature algorithm. Chameleon Signature is a non-interactive signature that operates on the hash and signature paradigm, exhibiting comparable efficiency to conventional schemes. Its distinct advantage lies in the fact that the owner of the public key does not necessarily require access to the corresponding secret key within the Chameleon hash algorithm. Notably, Chameleon signatures possess an inherent characteristic of non-transferability, with their validity ascertainable solely by designated recipients. This paper introduces the first Chameleon hash function based on both KKS and HFE schemes, showcasing its superiority over traditional schemes through rank metrics and big fields for enhanced security. The deployment of Chameleon hash functions within hash-and-sign signature schemes introduces a nuanced layer of security and verification flexibility. This study elucidates the implications of integrating Chameleon hash functions into the recipient’s public key infrastructure, highlighting the dual capability it affords authorized parties for secure and adaptable verification processes, alongside mechanisms for the detection of unauthorized alterations.

Data security is a very important compilation using cloud computing; one of the research that is running and using cloud technology as a means of storage is G-Connect. One of the developments made by the G-Connect project is about data security; most of the problems verification of the data sent. In previous studies, Keccak and RSA algorithms have implemented for data verification needs. But after a literature study of other algorithms that can make digital signatures, we found what is meant by an algorithm that is better than RSA in rectangular speeds, namely Digital Signature Algorithm (DSA).DSA is one of the key algorithms used for digital signatures, but because DSA still uses Secure Hash Algorithm (SHA-1) as an algorithm for hashes, DSA rarely used for data security purposes, so Keccak is used instead of the hash algorithm on DSA. Now, Keccak become the standard for the new SHA-3 hash function algorithm. Because of the above problems, the focus of this research is about data verification using Keccak and DSA. The results of the research are proven that Keccak can run on DSA work system, obtained a comparison of execution time process between DSA and RSA where both use Keccak.

Zero-knowledge proof (ZKP) is a fundamental cryptographic primitive that allows a prover to convince a verifier of the validity of a statement without leaking any further information. As an efficient variant of ZKP, noninteractive zero-knowledge proof (NIZKP) adopting the Fiat-Shamir heuristic is essential to a wide spectrum of applications, such as federated learning, blockchain, and social networks. However, the heuristic is typically built upon the random oracle model that makes ideal assumptions about hash functions, which does not hold in reality and thus undermines the security of the protocol. Here, we present a quantum solution to the problem. Instead of resorting to a random oracle model, we implement a quantum randomness service. This service generates random numbers certified by the loophole-free Bell test and delivers them with postquantum cryptography (PQC) authentication. By employing this service, we conceive and implement NIZKP of the three-coloring problem. By bridging together three prominent research themes, quantum nonlocality, PQC, and ZKP, we anticipate this work to inspire more innovative applications that combine quantum information science and the cryptography field.

Watermarking is largely used for copyright protection and fast search of images in databases. Another method for securely identifying images is to use hash functions. Digital signature standard, used in cryptosystem to dispute authentication documents, is based on hash functions. A digital signature is a bit stream dependent on key and content of document. For each document, the digital signature algorithm provides a unique output bit stream. In order to be efficient in images, the digital signature should be different if and only if the image content, and not the input bit stream, is different. Our new method is a one-way function for images. Using the radon transform and principal component analysis, we extract characteristics robust against geometrical transformation (rotation and scaling) and image processing attacks (compression, filtering, blurring).

Cryptographic algorithms form the backbone of decentralized finance (DeFi), ensuring secure, transparent, and tamper-proof transactions in blockchain ecosystems. These algorithms enable critical functionalities such as digital signatures, consensus mechanisms, and privacy preservation, empowering decentralized platforms to operate without intermediaries. This paper explores the role of cryptographic techniques, including asymmetric encryption, hash functions, and zero-knowledge proofs, in enabling DeFi applications like smart contracts, tokenization, and decentralized exchanges. Additionally, it examines emerging trends, such as post-quantum cryptography, to address vulnerabilities posed by quantum computing advancements. By investigating the intersection of cryptography and DeFi, this study highlights the challenges and opportunities in enhancing security, scalability, and interoperability within decentralized systems.

This paper analyzes the computer security of systems and importance of the digital signature and hashing message algorithm. The proposed digital signature algorithm gives a new technology for producing effective output of digital signature as a result the signing 1 and verifying of signatures are very fast compared to earlier ones. To improve the security and authentication of sending data, this method uses "Message Digest", "IDEA" and "GOST" 2 algorithms. The new message digest algorithm is to provide high security, to transfer data by combination of digital signature algorithm and symmetric key cryptography algorithm. The new hashing algorithm proposed creates a unique digital fingerprint along with symmetric key encryption generated IDEA and GOST algorithms 3,4 . The receiver used the symmetric key and hashing algorithm to form a signature. If this message digest match with the sender digests the message the content will be decrypted and read by sender.

Using digital signature (DS) algorithms to perform electronic messages authentication is an issue of significant importance for geographical information systems. The most computationally efficient DS algorithms are based on elliptic curves (EC) over finite fields. However, for many practical applications more efficient DS algorithms are required. To satisfy such performance requirements a new type of the finite groups is proposed as primitive for DS schemes. The elements of the proposed groups are vectors defined over the ground finite field. The group operation is the vector multiplication defined with some basis vector multiplication tables the characteristic feature of which is the use of expansion coefficients. It has been shown that the vector groups possess the multidimensionyclic structure and in special cases the dimension of the cyclicity is μ = 1. In such special cases the vector finite fields (VFFs) are formed. The DS algorithms based on EC over VFFs provides performance significantly higher than the performance of the known EC-based algorithms. Fast DS algorithms based on computations in vector finite groups corresponding to the case μ ≥ 2have also been proposed. KeywordsDigital signatureVector finite groupsMultidimension cyclicityVector finite fieldsElliptic curves

The hash function used is known for implementing algorithmic solutions in programming. Hash functions encrypt and optimize work with processed and stored data, as well as in various operating systems, ranking data to ensure their integrity. The application of the hash function is quite extensive. The usage of the hash function allows the possibility to solve almost all problems of protecting electronic information, from ensuring the authenticity of subjects and objects of information interaction to introducing uncertainty into the operation of means and objects of protection. The article deals with hash functions used in electronic digital signature (EDS) algorithms. Modern hashing methods and the areas in which they are applicable are described. The hash function is used to secure data. These functions can vary in bit depth, complexity, and cryptographic strength. Cryptographic hashing algorithms are given parameters, structures, and methods, as well as their scope. The work is devoted to analyzing hash functions and their application in the electronic digital signature. The article presents the results of calculating collisions of hashing algorithms, allowing you to choose the most optimal option for its application in the algorithm under consideration. The practical application of the hashing algorithm for the digital signature system, which can be used in systems and networks to transmit and store information, is considered

Public key cryptography or asymmetric keys are widely used in the implementation of data security on information and communication systems. The RSA algorithm (Rivest, Shamir, and Adleman) is one of the most popular and widely used public key cryptography because of its less complexity. RSA has two main functions namely the process of encryption and decryption process. Digital Signature Algorithm (DSA) is a digital signature algorithm that serves as the standard of Digital Signature Standard (DSS). DSA is also included in the public key cryptography system. DSA has two main functions of creating digital signatures and checking the validity of digital signatures. In this paper, the authors compare the computational times of RSA and DSA with some bits and choose which bits are better used. Then combine both RSA and DSA algorithms to improve data security. From the simulation results, the authors chose RSA 1024 for the encryption process and added digital signatures using DSA 512, so the messages sent are not only encrypted but also have digital signatures for the data authentication process.

Traditionally, information security needed encryption, authentication, key management, non-repudiation and authorization which were being met using several techniques. Standardization of algorithms by National Institute of Standards and Technology (NIST) has facilitated international communication for banking and information transfer using these standards. Encryption can be carried out using Advanced Encryption Standard (AES) using variable block lengths (128, 192 or 256 bits) and variable key lengths (128, 192 or 256 bits). Solutions for light weight applications such as those for Internet of Things (IoT) are also being standardized. Message integrity is possible using host of hash algorithms such as SHA-1, SHA-2 etc., and more recently using SHA-3 algorithm. Authentication is possible using well known Rivest-Shamir-Adleman (RSA) algorithm needing 2048/4096 bit operations. Elliptic Curve Cryptography (ECC) is also quite popular and used in several practical systems such as WhatsApp, Blackberry etc. Key exchange is possible using Diffie-Hellman algorithm and its variations. Digital Signatures can be carried out using RSA algorithm or Elliptic Curve Digital Signature Algorithm (ECDSA) or DSA (Digital Signature Algorithm). All these algorithms derive security from difficulty in solving some mathematical problems such as factorization problem or discrete logarithm problem. Though published literature gives evidence of solving factorization problem upto 768 bits only, it is believed that using Quantum computers, these problems could be solved by the end of this decade. This is due to availability of the pioneering work of Shor and Grover [1]. For factoring an integer of N bits, Shor’s algorithm takes quantum gates. As such, there is ever growing interest in being ready for the next decade with algorithms that may resist attacks in the quantum computer era. NIST has foreseen this need and has invited proposals from researchers all over the world. In the first round, about 66 submissions were received which have been scrutinized for completeness of submissions , novelty of the approach and security and 25 of these were promote to second round to improve based on the comments received on the first round submission. These will be analyzed for security and some will be selected for final recommendation for use by industry. These are for encryption/decryption, key agreement, hashing and Digital Signatures for both hardware and software implementations. In this paper, we present a brief survey of the state of the art in post-Quantum Cryptography (PQC) followed by study of one of technique referred to as Learning With Errors (LWE) in some detail.

While numerous digital signature schemes exist in the literature, most real-world system rely on RSA-based signature schemes or on the digital signature algorithm (DSA), including its elliptic curve cryptography variant ECDSA. In this position paper we review a family of alternative signature schemes, based on hash functions, and we make the case for their application in Internet of Things (IoT) settings. Hash-based signatures provide postquantum security, and only make minimal security assumptions, in general requiring only a secure cryptographic hash function. This makes them extremely flexible, as they can be implemented on top of any hash function that satisfies basic security properties. Hash-based signatures also feature numerous parameters defining aspects such as signing speed and key size, that enable trade-offs in constrained environments. Simplicity of implementation and customization make hash based signatures an attractive candidate for the IoT ecosystem, which is composed of a number of diverse, constrained devices.

Security method of data transmission process has been growing rapidly with the science of cryptography. Cryptography can provide security services that includes security aspects like confidentiality, data integrity, authentication and non-repudiation. Modern cryptography uses a key that must be kept secret to overcome the problem of cryptographic security. Problem in the use of the same key by two entities that communicate with each other in exchanging messages is a way to distribute the key. This problem can be overcome by using public-key cryptography, which allows users to communicate securely without a shared secret key. Digital signature is the application of public-key cryptography. When accessing important digital documents, it is necessary to verify the signature given. Implementation of digital signature always requires a hash function. Hash function used in this research namely SHA-256, SHA-384 and Tiger. Federal Information Processing Standards (FIPS) set the cryptographic standard for digital signatures is the Digital Signature Standard (DSS). Algorithms included in the DSS are the Digital Standard Algorithm (DSA), Ron Rives, Adi Shamir, and Leonard Adleman (RSA) and Elliptic Curve Digital Signature Algorithm (ECDSA). So it is necessary to test the best digital signature implementation strategy that can be used by optimizing the performance of the hash function. Performance testing of the three algorithms is done by making an application using a computer programming language C++. Implementation program using C++ class library for cryptographic scheme that is Crypto++ Library 5.6.0. Class libraries used in the classes functions for digital signatures. On the application of digital signatures generated, conducted tests is done by combining each hash function algorithm with each of the DSS in order to compare their performance in terms of time and memory usage. Against the test results are then analyzed using statistical tests. The result shows that pair of Tiger hash function and DSA algorithm is the best combination.

Data integrity, authenticity and non-repudiation are security parameters that provided by Digital Signature Algorithm (DSA). Hash value is important element inside DSA to identify information data integrity using hash function to generate message digest. Jpeg/exif is image file format that produce by digital camera as in smartphone. Hardware technology development made image file have higher resolution than before. This condition made image file fingerprinting need more time to compile jpeg/exif fingerprint. This research purpose is to develop fingerprinting process for jpeg/exif file using Boyer-Moore string matching algorithm and SHA512. Research conducted in four stages. First stage is jpeg/exif file structure identification, second stage is segment content acquisition and hashing, third stage is image file modification experiments and last stage is jpeg/exif file fingerprint compilation. Obtained result shown that jpeg/exif file fingerprint comprises of three hash value from SOI segment, APP1 segment and SOF0 segment. The jpeg/exif file fingerprint can use to detect six types image modification there are image resizing, text addition, metadata modification, image resizing, image cropping and file file type conversion.