Size Of Plaintext Research Articles

Towards Practical Transciphering for FHE with Setup Independent of the Plaintext Space

Fully Homomorphic Encryption (FHE) is a powerful tool to achieve non-interactive privacy preserving protocols with optimal computation/communication complexity. However, the main disadvantage is that the actual communication cost (bandwidth) is high due to the large size of FHE ciphertexts. As a solution, a technique called transciphering (also known as Hybrid Homomorphic Encryption) was introduced to achieve almost optimal bandwidth for such protocols. However, all existing works require clients to fix a precision for the messages or a mathematical structure for the message space beforehand. It results in unwanted constraints on the plaintext size or underlying structure of FHE based applications. In this article, we introduce a new approach for transciphering which does not require fixed message precision decided by the client, for the first time. In more detail, a client uses any kind of FHE-friendly symmetric cipher for { 0 , 1 } to send its input data encrypted bit-by-bit, then the server can choose a precision p depending on the application and homomorphically transforms the encrypted bits into FHE ciphertexts encrypting integers in ℤ p . To illustrate our new technique, we evaluate a transciphering using FiLIP cipher and adapt the most practical homomorphic evaluation technique [CCS'22] to keep the practical latency. As a result, our proof-of-concept implementation for p from 2 2 to 2 8 takes only from 13 ms to 137 ms.

Secure keys data distribution based user-storage-transit server authentication process model using mathematical post-quantum cryptography methodology

<abstract> <p>The central remote servers are essential for storing and processing data for cloud computing evaluation. However, traditional systems need to improve their ability to provide technical data security solutions. Many data security challenges and complexities await technical solutions in today's fast-growing technology. These complexities will not be resolved by combining all secure encryption techniques. Quantum computing efficiently evolves composite algorithms, allowing for natural advances in cyber security, forensics, artificial intelligence, and machine learning-based complex systems. It also demonstrates solutions to many challenging problems in cloud computing security. This study proposes a user-storage-transit-server authentication process model based on secure keys data distribution and mathematical post-quantum cryptography methodology. The post-quantum cryptography mathematical algorithm is used in this study to involve the quantum computing-based distribution of security keys. It provides security scenarios and technical options for securing data in transit, storage, user, and server modes. Post-quantum cryptography has defined and included the mathematical algorithm in generating the distributed security key and the data in transit, on-storage, and on-editing. It has involved reversible computations on many different numbers by super positioning the qubits to provide quantum services and other product-based cloud-online access used to process the end-user's artificial intelligence-based hardware service components. This study will help researchers and industry experts prepare specific scenarios for synchronizing data with medicine, finance, engineering, and banking cloud servers. The proposed methodology is implemented with single-tenant, multi-tenant, and cloud-tenant-level servers and a database server. This model is designed for four enterprises with 245 users, and it employs integration parity rules that are implemented using salting techniques. The experimental scenario considers the plain text size ranging from 24 to 8248 for analyzing secure key data distribution, key generation, encryption, and decryption time variations. The key generation and encryption time variations are 2.3233 ms to 8.7277 ms at quantum-level 1 and 0.0355 ms to 1.8491 ms at quantum-level 2. The key generation and decryption time variations are 2.1533 ms to 19.4799 ms at quantum-level 1 and 0.0525 ms to 3.3513 ms at quantum-level 2.</p> </abstract>

A probabilistic public key encryption switching scheme for secure cloud storage

The high demand for user-centric applications such as secure cloud storage laid the foundation for the development of user-centric security schemes with multiple security features in recent years. But, the current state-of-art techniques primarily emphasized only one type of security feature i.e., either homomorphism or non-malleability. To fill this gap and provide a common platform for both homomorphic and non-malleable cloud applications, we have introduced a new public key-based probabilistic encryption switching method. The proposed scheme generates {mathcal {O}}(m+2 log N) bits of ciphertext where min {mathbb {N}} and m<n, nin {mathbb {N}} is the plaintext size, N is the RSA composite. The superior performance of the proposed scheme has been tested in comparison to existing methods and is reported in this paper.

Differential Fault Analysis on the Key Schedule of the LBlock Algorithm

In 2011,Wu and Zhang proposed a lightweight block cipher named LBlock, whose plaintext size and key size are 64 bits and 80 bits, respectively. As they said, LBlock can be efficiently implemented in constrained hardware environments, such as wireless sensor network. In this paper, we study the security of LBlock against the differential fault analysis (DFA) on its key scheduling. As far as we know, this is the first time the DFA on key schedule is used to analyze LBlock. More concretely, our DFA attack adopts the random nibble fault model. When the fault is injected in the subkeys in round 30 and 31, most bits of the subkeys in round 31 and 32 can be recovered, which leads to the leakage of the bits of master secret key according to the key scheduling. A quantitative analysis of the input-output differentials of the S-boxes in LBlock shows that our attack reduces the searching space of master key from 2⁸⁰ to 2²³. Then the exhaustive search of all 2²³ possible keys can uniquely determine the true master key. Finally, we also implement LBlock and simulate the DFA on its key scheduling. The experiment results show that our attack is effective.

Actively Secure Setup for SPDZ

We present the first actively secure, practical protocol to generate the distributed secret keys needed in the SPDZ offline protocol. As an added bonus our protocol results in the resulting distribution of the public and secret keys are such that the associated SHE ‘noise’ analysis is the same as if the distributed keys were generated by a trusted setup. We implemented the presented protocol for distributed BGV key generation within the SCALE-MAMBA framework. Our method makes use of a new method for creating doubly (or even more) authenticated bits in different MPC engines, which has applications in other areas of MPC-based secure computation. We were able to generate keys for two parties and a plaintext size of 64 bits in around 5 min, and a little more than 18 min for a 128-bit prime.

Compressible Multikey and Multi-Identity Fully Homomorphic Encryption

With the development of new computing models such as cloud computing, user’s data are at the risk of being leaked. Fully homomorphic encryption (FHE) provides a possible way to fundamentally solve the problem. It enables a third party who does not know anything about the secret key and plaintexts to homomorphically perform any computable functions on the corresponding ciphertexts. In 2009, Gentry proposed the first FHE scheme. After that, its inefficiency has always been a bottleneck of the development of practical schemes and applications. At TCC 2019, Gentry and Halevi proposed the first compressible FHE scheme that enables the ratio of plaintext size to the ciphertext size (i.e., the compression rate) to reach1−εfor any smallε&gt;0under the standard learning with errors (LWE) assumption. However, it is only a single-key one, where the homomorphic evaluation can only be performed over ciphertexts encrypted under the same key. Compared with single-key FHE, multikey FHE is more practical. Multikey FHE enables ciphertexts encrypted under different public keys to be homomorphically computed without having to decrypt these ciphertexts using their own private keys. In addition, in a multi-identity FHE scheme, only identity information and public parameters are required when encrypting, which simplifies certificate-based key management in public key infrastructure. In this paper, a new compressible ciphertext expansion technique is proposed. Then, we use this technique to construct a compressible multikey FHE scheme and a compressible multi-identity FHE scheme to overcome the bottleneck of bandwidth inefficiency in the multikey and multi-identity settings. The two schemes proposed in this paper make it possible that the objects of homomorphic operation can be the ciphertexts encrypted under different keys or different identities before compression, thus solving the single-key defect of the work of Gentry and Halevi.

Encryption and Decryption Algorithms in Symmetric Key Cryptography Using Graph Theory

The present-day society depends heavily on digital technology where it is used in many applications such as banking and e-commerce transactions, computer passwords, etc. Therefore, it is important to protect information when storing and sharing them. Cryptography is the study of secret writing which applies complex math rules to convert the original message into an incomprehensible form. Graph theory is applied in the field of cryptography as graphs can be simply converted into matrices There are two approaches of cryptography; symmetric cryptography and asymmetric cryptography. This paper proposes a new connection between graph theory and symmetric cryptography to protect the information from the unauthorized parties. This proposed methodology uses a matrix as the secret key which adds more security to the cryptosystem. It converts the plaintext into several graphs and represents these graphs in their matrix form. Also, this generates several ciphertexts. The size of the resulting ciphertexts are larger than the plaintext size.

Advance image encryption technique utilizing compression, dynamical system and S-boxes

Chaos theory is initially developed in the 1970s and has been utilized in the field of cryptography for the last three decades. In present work, an implementation of image encryption technique using chaotic system, compression and S-boxes is discussed. In this encryption scheme, compression is used to hide the original size of (plain text) image and also reduce the time complexity of the scheme. In addition to this, a particular S-box is selected for the encryption process with the help of an improved range chaotic map. The proposed scheme is discussed in detail, along with its standard security analysis and experimental results. This improved chaotic map and S-boxes provide large key space and high level of security. The size of cipher text generated by this scheme is different from plain text and is easy to implement for practical application of secure transmission of confidential data.

Symmetric Encryption Algorithm using ASCII Values

Cryptography at its very core is nothing but math - pure, simple, undiluted math. Math created algorithms that are basics for various encryption algorithm. Encryption is a method in which user’s confidential data or private data is encoded to cipher text and this text can be read only if it is decrypted by authorized user using the right key. Cipher text can be decoded back to plain text, only by the authorized users using a right key. Various encryption algorithm are used to encrypt the plain text to cipher text and the cipher text is decrypted back to plain text by authorized user using right key. The symmetric key algorithm uses the same key to encrypt the plain text and decrypt the cipher text. In this paper we have proposed new symmetric algorithm using ASCII value. The plain text using key and ASCII values is converted to cipher text. Encryption algorithm sends cipher text and minimum value to the authorized receiver. Receiver decrypts the cipher text to plain text using same key and minimum value. In this algorithm sequence of five pseudo random number is generated and sum of this five pseudo random number is added to the obtained decimal value. Seed to generate common sequence of pseudo random number is kept secret between sender and receiver. Proposed algorithm support variable key length and plain text size. This algorithms performs faster when text is small message, but the execution time increases as the plain text size increases. This algorithm can be used to send small messages in a secured way. .

Cryptosystem design based on Hermitian curves for IoT security

The ultimate goal of modern cryptography is to protect the information resource and make it absolutely unbreakable and beyond compromise. However, throughout the history of cryptography, thousands of cryptosystems emerged and believed to be invincible and yet attackers were able to break and compromise their security. The main objective of this paper is to design a robust cryptosystem that will be suitable to be implemented in Internet of Things. The proposed cryptosystem is based on algebraic geometric curves, more specifically on Hermitian curves. The new cryptosystem design is called Hermitian-based cryptosystem (HBC). During the development of the HBC design, Kerckhoffs’s desideratum was the main guidance principle, which has been satisfied by choosing the Hermitian curves as the core of the proposed design. The proposed HBC inherits all the advantageous characteristics of Hermitian curve which are large number of points that satisfy the curve and high genus curves. The aforementioned characteristics play a crucial role in generating a large size encryption key for HBC and determine the block size of plaintext. Due to the fact that HBC used algebraic geometric codes over Hermitian curve, it has the ability to perform error correction in addition to data encryption. The error correction is another advantage of HBC compared with many existing cryptosystems such as McEliece cryptosystem. The number of errors that can be corrected by HBC is larger (high data rate) than other algebraic geometric codes such as elliptic and hyperelliptic curves. It also uses non-binary representation which increases its attack resistance. In this paper, the proposed HBC has been mathematically compared with elliptic curve cryptosystem. The results show that HBC has many advantages over the elliptic curves in terms of number of points and genus of the curve.

Accelerating Information Security in Cloud Computing using a Novel Holomorphic Scheme

In the past decades, many security algorithms are invented and used in many applications for encryption and decryption of information or data. All the secure algorithms were uses the security key of size 8bit, 16bit, 32bit, 64bit and 128bits for encryption and decryption but literature survey says that higher the key size, higher the security. But the higher key size has number more bits and its requires more memory for storage and also to perform each and every bit through computational operations leads to more delay. To address these issues, the key and plain text are of 128bits and converted into integer. The converted integer values of key and plaintext are encrypted and decrypted using Holomorphic through Advanced Encryption Standard (AES). The research method is sophisticated and more protected through meaning fully lesser key in size and is accomplished for encryption in terms integer key and plaintext moderately than binary bits, therefore larger size of key and plaintext can be minimized and reduced the computational complexities. Finally the cipher text is uploaded into cloud through Real Time Transport Protocol (RTP) and Real Time Transport Control Protocol (RTCP) for storage. The main problem with continuous sharing of information into cloud is security attacks so in this research work, three different multimedia signals such as ECG, EEG and biomedical images are converted into integer and encrypted using AES. The stored data can access by the authorized users and can decode the information after decryption using AES.

Improved RC6 Algorithm using Two Types of Chaos Maps

RC6 (Rivest cipher 6) is keyblock chipher which consider symmetric imitative from RC5. It was intended to encounter the needs competition of the Advanced Encryption Standard (AES) . The aim of this work is to add new security layer to RC6 (Rivest Cipher 6) algorithm, because there is some insufficiency in the Key Scheduling Algorithm (KSA) of RC6. This paper presents improved RC6 (IRC6) key generation based on two types of chaotic maps (Chebyshev,2d logistic) to generate N key to N users. The results prove that the average secrecy of IRC6 is better than of traditional RC6, in which: for 32 bits’ key length, and 256 bits’ plaintext size, the average secrecy of IRC6 is (0.536 - 3.907) while for RC6 is (0.254 constant).

Implementation of an Attribute-Based Encryption Scheme Based on SM9

In recent years, attribute-based encryption (ABE) has been widely applied in mobile computing, cloud computing, and the Internet of things, for supporting flexible and fine-grained access control of sensitive data. In this paper, we present a novel attribute-based encryption scheme that is based on bilinear pairing over Barreto and Naehrig curves (BN-curves). The identity-based encryption scheme SM9, which is a Chinese commercial cryptographic standard and a forthcoming part of ISO/IEC11770-3, has been used as the fundamental building block, and thus we first introduce SM9 and present our SM9 implementation in details. Subsequently, we propose the design and implementation of the ABE scheme. Moreover, we also develop a hybrid ABE for achieving lower ciphertext expansion rate when the size of access structure or plaintext is large. The performance and energy consumption of the implementation of the proposed ABE and its hybrid version are evaluated with a workstation, a PC, a smart phone, and an embedded device. The experimental results indicated that our schemes work well on various computing platforms. Moreover, the proposed schemes and their implementations would benefit developers in building applications that fulfill the regulatory compliance with the Chinese commercial cryptographic standard since there is no existing ABE scheme compatible with any Chinese cryptographic standard.

Performance analysis of hybrid cryptosystem - A technique for better security using blowfish and RSA

Security is the most concerned topic in this today’s world of Information and Communication Technology. Single layer security can be breached easily so hybrid cryptographic system has been introduced. Hybrid system can be made by combining two or more algorithms of similar or dissimilar types. Here, combing of Blowfish algorithm along with RSA algorithm is performed. After combination their performance analysis is done based on five parameters namely Throughput, Encryption time, Decryption time, Total Execution time and Plain text size to cipher text size ratio with different key size of Blowfish algorithm ranging from 32 bit-448 bit. Among these 5 different hybrid cryptosystem we found that the Blowfish RSA system with key size 448 bit has better performance than all other bit size.

A chaos-based probabilistic block cipher for image encryption

Traditional encryption is based on secrecy provided by secret-key. But this leads to generation of same cipher text when the encryption scheme is applied to same plaintext with same key. Thus, replay of messages can be effortlessly identified by an adversary which can be a weak link in any communication. Probabilistic encryption is an approach to overcome this weakness where different cipher texts are generated each time same plaintext is encrypted using the same key.Extending the probabilistic approach, which is generally employed in asymmetric encryption, this paper proposes a new chaos-based probabilistic symmetric encryption scheme with customizable block-size suitable for image encryption. It employs a Random Bits Insertion phase followed by four rounds of two-staged diffusion involving simple XOR (exclusive-OR) operation making it computationally efficient. Random Bits Insertion makes the scheme probabilistic. This phase also helps in increasing entropy and making intensity distribution more uniform in cipher. The generated cipher text is twice the size of plain text. An increase in cipher text space is inevitable for probabilistic encryption and it provides an advantage as the apparent message space for the attacker is increased. The observations show that the scheme offers high strength to resist statistical and cryptanalytic attacks.

Encoding of Rational Numbers and Their Homomorphic Computations for FHE-Based Applications

This work addresses a basic problem of security systems that operate on very sensitive information. Specifically, we are interested in the problem of privately handling numeric data represented by rational numbers (e.g., medical records). Fully homomorphic encryption (FHE) is one of the natural and powerful tools for ensuring privacy of sensitive data, while allowing complicated computations on the data. However, because the native plaintext domain of known FHE schemes is restricted to a set of quite small integers, it is not easy to obtain efficient algorithms for encrypted rational numbers in terms of space and computation costs. For example, the naïve decimal representation considerably restricts the choice of parameters in employing an FHE scheme, particularly the plaintext size. Our basic strategy is to alleviate this inefficiency by using a different representation of rational numbers instead of naïve expressions. In this work we express rational numbers as continued fractions. Because continued fractions enable us to represent rational numbers as a sequence of integers, we can use a plaintext space with a small size while preserving the same quality of precision. However, this encoding technique requires performing very complex arithmetic operations, such as division and modular reduction. Theoretically, FHE allows the evaluation of any function, including modular reduction at encrypted data, but it requires a Boolean circuit of very high degree to be constructed. Hence, the primary contribution of this work is developing an approach to solve this efficiency problem using homomorphic operations with small degrees.

Improved RC4 Algorithm Based on Multi-Chaotic Maps

The aim of this study is to overcome on the weakness points in RC4 (Rivest Cipher 4) algorithm, there are some blemishes in the Key Scheduling Algorithm (KSA) of RC4. This study presented improved RC4 key generation based on multi-chaotic maps. The new version of KSA coined as improved KSA (IKSA), the permutation of the S array modified to depend on the random numbers generator based on three chaotic maps and the proposed algorithm outputs as follows: Output = M XOR Generated key XOR Random value from IKSA (R3w) The improved RC4 with IKSA is tested for its secrecy, randomness and performance over the variable key length and different plaintext size with respect to those of the original RC4.The results show that the improved RS4 with IKSA is better than the original RC4 with KSA.

An Improved IDEA-ECB Based on Multithread Technology

In terms of the problem that the encryption rate of International Data Encryption Algorithm (IDEA) is low, and it’s throughout capacity is small under the ECB packet mode, this paper proposes a kind of improved IDEA-ECB based on multithread technology. Change the order flow of single thread into concurrent flow of multithread with clocking plaintext and multithread technology, which improve the encryption rate and throughout capacity, at the same time reduce the operation hours of encryption algorithm, and satisfy the demand that real time and high effectively software encryption in instant messaging. Experimental results show that if the size of plaintext is 1MB, the number of threads which is started respectively is 4,8,12,16, the speedup of improved algorithm increases 1.72~4.08 times than classical algorithm.

Extending Feistel structure to DNA Cryptography

DNA cryptography is a novel field being taken up by the researcher community for research now days in order to have secure communication on a network. This technique is inspired from biological science, in which DNA is used as an information carrier from one generation to another. DNA cryptography is proposed for a secure end to end communication due to the vast parallelism and extra ordinary information density that are inherent in any DNA molecule. In this paper previous algorithm based on DNA cryptography is enhanced in terms of its security parameter by incurring feistel inspired structure in it. This adds some sort of confusion and diffusion, which makes it complex enough that it restricts the adversary to perform any kind of brute force attack. Encryption and decryption time is also compared on the basis of variable plaintext size.

Measurement-based research on cryptographic algorithms for embedded real-time systems

Security, energy and timing are three main concerns for embedded real-time systems, especially in battery-powered security-critical embedded systems. Existing researches on cryptographic algorithms seriously ignored the timing properties and their running environments were supposed for general applications while not based on real-time operating systems. In this paper we make efforts to analyse both energy and time related characteristics of widely used cryptographic algorithms for data-sensitive embedded real-time systems. All our studies are based on empirical data measured from a widely used ARM9 developing platform which runs security-critical test tasks within the real-time operating systems μ C/OSII. To efficiently obtain precise and accuracy data, we use NI instrument and devise a well-defined data-processing method. Identifying the inherent characteristics of security algorithms, we propose a multi-dimensional analysis framework that reveals potential features cryptographic algorithms from the angles of power, speed, and unit energy cost. The energy and time features of most popular cryptographic algorithms including symmetric, asymmetric, and hash algorithms are well studied. In addition, some mathematical models are also built to help explain and investigate these features. Based on the experiments and analysis, we found some interesting results like (1) energy consumptions and time overheads of cryptographic algorithms are not linear functions of the size of plain text, (2) energy cost is near-linear to the execution time of each cryptographic algorithm under any data size due to the hard/software experimental platform constraint, (3) the power is a Gaussian function of data size while the processing speed and unit energy are polynomial functions of data size. We believe this paper could help the design of security-critical applications in embedded real-time systems, e.g. utilizing directly these experimental data of cryptographic algorithms or these fitting mathematical functions to optimize the energy consumption of security-critical real-time applications under limited resources and security requirements.