Ciphertext Bits Research Articles

An Image Steganographic Scheme Based on Edge Detection and Least Significant Bit Substitution

<p>This work presents a steganographic scheme based on Laplacian-of-Gaussian (LoG) edge detection and least significant bit (LSB) substitution. The cover image is first divided into continuous and non-overlapping 4×4-pixel blocks. The pixel at the top left corner of each block (first pixel) is defined as the reference pixel. After the LoG edge detection, the blocks are classified as edge or non-edge blocks, and this information is embedded in the reference pixels. Each non-reference pixel is then embedded with 5 bits and 4 bits of cipher text if it belongs to an edge block or non-edge block, respectively. Compared to the method of Tseng and Leng, Bai et al., and Ghosal et al., proposed method increased the capacity by 39.6%, 7.3%, and 42.7%, respectively, in the “Lena” cover image. To test the generalizability of our method, an embedding capacity and image quality test were conducted using 10,000 512 × 512 sized greyscale images from the BOSSBase dataset. Compared to the aforementioned previous methods, our method improved the capacity by 33.9%, 2.7%, and 36.1%, respectively, while maintaining an acceptable stego-image quality. Finally, proposed method can resist the detection of RS, pixel difference histogram analysis and second order SPAM features.</p> <p> </p>

Quantum encryption with quantum permutation pad in IBMQ systems

Quantum permutation pad or QPP is a quantum-safe symmetric cryptographic algorithm proposed by Kuang and Bettenburg in 2020. The theoretical foundation of QPP leverages the linear algebraic representations of quantum gates which makes QPP realizable in both, quantum and classical systems. By applying the QPP with 64 of 8-bit permutation gates, holding respective entropy of over 100,000 bits, we accomplished quantum random number distributions digitally over today’s classical internet. The QPP has also been used to create pseudo quantum random numbers and served as a foundation for quantum-safe lightweight block and streaming ciphers. This paper continues to explore numerous applications of QPP, namely, we present an implementation of QPP as a quantum encryption circuit on today’s still noisy quantum computers. With the publicly available 5-qubit IBMQ devices, we demonstrate quantum secure encryption (256 bits of entropy) using 2-qubit QPP with 56 permutation gates, and 3-qubit QPP with 17 permutation gates respectively. Initial qubits of the encryption circuit correspond to the plaintext and after applying quantum encryption operations, cipher qubits are measured with probabilistic distributions, and the results with the highest probability are recorded as cipher bits. The cipher bits are then decrypted with an inverse QPP circuit. The output state plaintext qubits are measured and the most frequent count measurement results are recorded as plaintext bits. This quantum encryption and decryption process clearly demonstrates that QPP quantum implementations works exactly as symmetric encryption and decryption schemes should. The plaintext and ciphertext bits can also be encrypted and decrypted respectively by any classical computing device with the corresponding QPP algorithm as in quantum computers. This work reveals that it is possible to build quantum-secure communications between quantum-to-quantum and quantum-to-classical computers over today’s internet and the future quantum internet.

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.

A Classical and Machine Learning-Based Reliability Analysis on Catalan Object Encryption Scheme

Designing <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">lightweight</i> secure cryptographic schemes for Internet of Things (IoT) and radio frequency identification (RFID)-based devices is challenging as a designer needs to address resource-constraints along with physical and classical security notions. Even though plethora of such lightweight encryption schemes have been proposed in the literature, computationally efficient attacks on some has also been published, which stresses the fact that robust and reliable design paradigms to consider during design process. In this article, using classical methods, we launched the full-key attack on a Catalan-object-based encryption scheme proposed by Saracevic <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et al.</i> (2020) in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"/> IEEE Transactions on Reliability <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"/> . Their proposed encryption scheme is efficient and lightweight specifically meant for IoT applications and is based upon combinatorial structure of Catalan key objects. We proved data privacy violation and recover the full encryption-key with computationally efficient algorithm. We also proposed the machine-learning-based regression model to efficiently predict all bits of ciphertext using just a single plaintext without any key. A high correlation between plaintext and ciphertext and full-key recovery poses the encryption scheme to be unreliable to be used for IoT-based applications. To the best of authors’ knowledge, this is the first work on reliability analysis on Catalan-based encryption schemes.

Framework for faster key search using related‐key higher‐order differentialproperties: applications to Agrasta

The relevance of the related-key model is usually controversial. However, in some cases, related-key properties have already been used to reduce the effective key length of the cipher in the single-key model. Hence, research into this direction can be helpful to bridge the gap between theory and practice aspects of the related-key model. Motivated by this challenge, the authors develop a new framework to provide further evidence that deterministic related-key characteristics can be utilised in the single-key model. The authors describe a sound framework for utilising related-key higher-order differential distinguishers that can beat the boundaries given by exhaustive key search. The data required is only one known as plaintext–ciphertext pair if the number of ciphertext bits matches the key length. From a theoretical point of view, the connection between related-key higher-order differential properties and the security of cryptographic primitives in the single-key model are precised. From a practical point of view, the proposed framework is used to evaluate the security of Agrasta cipher which is a variant of Rasta cipher presented at CRYPTO 2018. The proposed method is the first analysis of Agrasta reduced to three rounds that performs better than exhaustive key search and is independent of the used linear layers.

Immunity of Lightweight DES Algorithm (DESL) Against Linear Cryptanalysis Attack

Lightweight DES Algorithm (DESL) was introduced by Axel Poschmann et.al as a strong, compact and efficient encryption algorithm suitable for constraint resource like WSNs, RFID and IOT devices. This paper discusses the security of the DESL against Linear Cryptanalysis which is a known plaintext attack in which a large number of plaintext-ciphertext pairs are used to determine the value of key bits. Linear cryptanalysis works on the principle of finding “high probability occurrences of linear expressions involving plaintext bits, ciphertext bits, and subkey bits”. Furthermore, we show that DESL is more resistant against the linear cryptanalysis attack than classical DES.

Determining whether a given cryptographic function is a permutation of another given cryptographic function—A problem in intellectual property

Imagine that, in order to avoid patent fees, licensing agreements, or export restrictions, someone permutes the plaintext bits, ciphertext bits, or key bits of a block cipher. All security properties of the block cipher would be preserved. There are many possible such permutations (e.g. 23116.32 for the Advanced Encryption Standard, AES-256). It might seem infeasible to detect this fraud, and even harder to determine the permutation matrices used. Instead of a block cipher, it could be the compression function of a cryptographic hash, or any other cryptographic function.This paper presents an algorithm whereby this fraud could be easily detected, by means of a SAT-Solver—a standard off-the-shelf software package that solves small-to-medium sized instances of the logical satisfiability problem. This paper also presents how this problem can be modeled in a system of polynomial equations (e.g. in the context of algebraic cryptanalysis). Moreover, this problem is related to the “isomorphism of polynomials” problem and that connection is explored at length.

Cryptanalysis of Round-Reduced Fantomas, Robin and iSCREAM

In this work, we focus on LS-design ciphers Fantomas, Robin, and iSCREAM. LS-designs are a family of bitslice ciphers aimed at efficient masked implementations against side-channel analysis. We have analyzed Fantomas and Robin with a technique that previously has not been applied to both algorithms or linear cryptanalysis. The idea behind linear cryptanalysis is to build a linear characteristic that describes the relation between plaintext and ciphertext bits. Such a relationship should hold with probability 0.5 (bias is zero) for a secure cipher. Therefore, we try to find a linear characteristic between plaintext and ciphertext where bias is not equal to zero. This non-random behavior of cipher could be converted to some key-recovery attack. For Fantomas and Robin, we find 5 and 7-round linear characteristics. Using these characteristics, we attack both the ciphers with reduced rounds and recover the key for the same number of rounds. We also apply linear cryptanalysis to the famous CAESAR candidate iSCREAM and the closely related LS-design Robin. For iScream, we apply linear cryptanalysis to the round-reduced cipher and find a 7-round best linear characteristics. Based on those linear characteristics we extend the path in the related-key scenario for a higher number of rounds.

A Key-Ordered Decisional Learning Parity with Noise (DLPN) Scheme for Public Key Encryption Scheme in Cloud Computing

The variation of decisional learning parity with noise (DLPN) named as key-Ordered DLPN based security algorithm is presented in this work. The proposed scheme uses DLPN by extending it to an even-odd-order scheme, depend on the value of probability distribution of odd and even bits for encryption, where odd and even bits are the input integer values for key generation algorithm. This states that the probability distribution of odd and even bits are ordered based on the key generation, the process of odd and even bits resolving is the solution of DLPN attacker problems, thus, the proposed scheme provides more correctness and security proof. Through the learning parity with noise (LPN), DLPN and RSA algorithms, the proposed system is evaluated, to measure the encryption time, public key and ciphertext bits.

Implementasi Algoritma Data Encryption Standard Pada Penyandian Record Database

Record databases are generally still often displayed in text form as information for users, so it can facilitate cryptanalyst to access and provide opportunities to do the leak, distribute or modify the database records. One of the cryptographic algorithms used to secure data is using the DES algorithm to encrypt the data to be stored or sent. The DES algorithm belongs to a cryptographic system of symmetry and is a type of block cipher. DES operates on a 64-bit block size. DES describes 64 bits of plaintext to 64 bits of ciphertext using 56 bits of internal key (internal key) or up-key (subkey). The internal key is generated from an external key 64-bit length. This research describes the process of securing database records by encrypting it based on DES algorithm, resulting in text record databases in the form of passwords that are difficult to understand and understand by others. This is done in an attempt to minimize the misuse of database records.

Efficient hierarchical identity based encryption scheme in the standard model over lattices

Using lattice basis delegation in a fixed dimension, we propose an efficient lattice-based hierarchical identity based encryption (HIBE) scheme in the standard model whose public key size is only (dm 2 + mn) log q bits and whose message-ciphertext expansion factor is only log q, where d is the maximum hierarchical depth and (n, m, q) are public parameters. In our construction, a novel public key assignment rule is used to averagely assign one random and public matrix to two identity bits, which implies that d random public matrices are enough to build the proposed HIBE scheme in the standard model, compared with the case in which 2d such public matrices are needed in the scheme proposed at Crypto 2010 whose public key size is (2dm 2 + mn +m) log q. To reduce the message-ciphertext expansion factor of the proposed scheme to log q, the encryption algorithm of this scheme is built based on Gentry’s encryption scheme, by which m 2 bits of plaintext are encrypted into m 2 log q bits of ciphertext by a one time encryption operation. Hence, the presented scheme has some advantages with respect to not only the public key size but also the message-ciphertext expansion factor. Based on the hardness of the learning with errors problem, we demonstrate that the scheme is secure under selective identity and chosen plaintext attacks.

XOR Encryption Versus Phase Encryption, an In-Depth Analysis

Encryptions are used in almost all standards to ensure the confidentiality of the data. Encryptions can be and indeed are implemented in the different layers of a network protocol stack. Conventional encryption performs the bitwise XOR operation between one message bit and one key stream bit to generate one ciphertext bit. Huo et al. have recently proposed to provide confidentialities on the user data by performing the phase encryption on the time domain OFDM samples in LTE system. Phase encryption is performed on the modulated symbols, different from the bit level of XOR encryption, i.e., stream cipher encryption. In this paper, we extend their study. We first generalize the phase encryption to general communication systems independent of the underlying modulation scheme. Then, we formulate the mathematical models for XOR and phase encryptions. Based on our model, we compare these two encryption methods in terms of their security and encryption efficiency. We also show phase encryption can resist traffic analysis attack when implemented in the physical layer. Finally, we conduct simulations to compare the performance of these two methods in terms of their decoding symbol error rate.

Hiding of Random Permutated Encrypted Text using LSB Steganography with Random Pixels Generator

world of growing technology, network security and protection of data have been of great concern. Steganography is the art of hiding a private message with in a cover file in such a manner that third party cannot know the existence of the hidden message. Steganography has many different forms like LSB, transforms, masking, and filtering technique. Enhanced LSB technique is main concern of this paper. The implementation in this paper is concern with five features. First one is deal with the generation of truly random and secure encryption key, second feature deals with encrypt the secret message using AES algorithm, third feature deals with generation of permutation technique to distribute the encrypted message bits randomly, fourth feature dealing with generation of random pixels number in order to hide the secret encrypted message bits inside them, finally the fifth features id dealing with the hiding the random ciphertext bits within random image pixels. This paper proposed an enhanced hiding system with analysis of the proposed system.

A Robust Image Steganography Technique Using Dynamic Embedding with Two Least Significant Bits

In this paper we are proposing a new Image steganography technique for secure communication between sender and receiver. At the sender we follow two steps. In the first step we encrypt the secret information by blowfish algorithm and in second step we embed the cipher text in LSB minus one and LSB (least significant bit) locations of some of the selected pixels (bytes) of the carrier image. One pixel is 8 bits in 8-bit gray scale. The selection of the pixels is done by a dynamic evaluation function. Depending on the cipher text bits, the dynamic evaluation function decides on which pixels the different cipher text bits are to be embedded. At the receiver also two steps are followed, first the cipher bits are retrieved from the image from the said locations and then it is decrypted by using the blowfish algorithm to get the secret information. As the embedding byte locations are decided based on bits of the cipher text, so it is dynamic steganography. This approach provides two levels of security, one at the cryptography level and the other at the steganography level. The proposed technique is experimented through a large number of experiments.

A Dynamic Approach to Image Steganography Using the Three Least Significant Bits and Extended Hill Cipher

In this paper we propose a technique for secure communication between sender and receiver. We use both cryptography and steganography. We take image as the carrier to use steganography. We have extended the existing hill cipher to increase its robustness and used it as our cryptography algorithm. By using this extended hill cipher (a new block cipher) which uses a 128 bit key, we encrypt the secret message. Then the cipher text of the secret message is embedded into the carrier image in 6th, 7th and 8th bit locations of some of the selected pixels (bytes). The 8th bit in a pixel (byte) is called as the least significant bit (LSB). The pixel selection is done depending on the bit pattern of the cipher text. So for different messages the embedding pixels will be different. That means to know the pixels of the image where the cipher text is embedded we should know the cipher text bits. Thus it becomes a stronger steganography. As the pixels where we embed are chosen during the run time of the algorithm, so we say that it is dynamic steganography. After embedding the resultant image will be sent to the receiver, the receiver will apply the reverse process what the sender has done and get the secret message.

Security problems with improper implementations of improved FEA-M

This paper reports security problems with improper implementations of an improved version of FEA-M (fast encryption algorithm for multimedia). It is found that an implementation-dependent differential chosen-plaintext attack or its chosen-ciphertext counterpart can reveal the secret key of the cryptosystem, if the involved (pseudo-)random process can be tampered (for example, through a public time service). The implementation-dependent differential attack is very efficient in complexity and needs only O( n 2) chosen plaintext or ciphertext bits. In addition, this paper also points out a minor security problem with the selection of the session key. In real implementations of the cryptosystem, these security problems should be carefully avoided, or the cryptosystem has to be further enhanced to work under such weak implementations.

Information leakage of Feistel ciphers

We examine the information leakage between sets of plaintext and ciphertext bits in symmetric-key block ciphers. The paper demonstrates the effectiveness of information leakage as a measure of cipher security by relating information leakage to linear cryptanalysis and by determining a lower bound on the amount of data required in an attack from an upper bound on information leakage. As well, a model is developed which is used to estimate the upper bound on the information leakage of a general Feistel (1975) block cipher. For a cipher that fits the model well, the results of the analysis can be used as a measure in determining the number of rounds required for security against attacks based on information leakage. It is conjectured that the CAST-128 cipher fits the model well and using the model it is predicted that information leaked from 20 or fewer plaintext bits is small enough to make an attack on CAST-128 infeasible.

Nondegenerate functions and permutations

One of the basic design criteria for a block encryption function is to ensure that for each fixed key, each ciphertext bit depends nonlinearly on each plaintext bit. When the ciphertext is represented using boolean equations depending on the key and plaintext, these equations should then be nondegenerate so that it is possible that each bit of the key and plaintext can influence each ciphertext bit. We prove that nondegeneracy in a boolean function can be verified in linear time on average. We study higher order nondegeneracy and prove that for balanced n-bit functions, on average, at least n — [ log n]— 2 input bits must be held constant before a degenerate subfunction is induced. We also prove that the fraction of n-bit permutations within the symmetric group that are realized by nondegenerate boolean functions tends to one as n increases. Letting N n, n be the set of nondegenerate permutations, we formally prove that 1 −L n < ¦ N n,n¦2 n! < 1 − L n + U n, (1) where U n, L n ϵ o(1).

On a method of cryptanalysis for cryptosystem with involution

AbstractCryptology provides the technological basis for guaranteed network security. In the field of business, to guarantee the security of information, everyone needs easy‐to‐use cryptology. Starting with the announcement by the U.S. National Bureau of Standards of the DES cryptosystem and the proposal by NTT of the FEAL cryptosystem, secret‐key cryptographic algorithms have been published, involution‐type block cryptosystems which use secret key to encipher 64 bits of plain text as 64 bits of cipher text [2, 3, 9, 10, 12]. NTT has pro posed the one‐way function MAP, which is also an invo lution‐type transform. In this paper, we study a new cryptanalytic method for involution‐type cryptosystems and show by example that it can be applied practically in a ciphertext‐only attack on the one‐way function MAP. For an involution‐type cryptosystem, by increasing the amount of construction in the data‐randomization phase and by increasing the size of the secret key, we can guarantee the computational security by preventing the estimation of the secret key. However, if we study the properties of the function used in the design of the data‐ randomization phase, by specifying input/output values of the function which are independent of the secret key, it may be possible to use the inverse function [11] to calculate the secret key. This method is called the inter Mediate cipher method. the intermediate cipher method differs from previous methods in the small quantity of data required for breaking.

GeoSight fact finder, GIS based software package

The Data Encryption Standard (DES) or Data Encryption Algorithm (DEA), ANSI standard X3.92-1981, is a well known symmetric block cipher. In the basic mode of operation, electronic code book mode, it encrypts blocks of 64 bits of plain text into 64 bits of cipher text using a 56-bit key. Its internal structure, which is highly non-linear and contains 18 permutations and 16 expansions of bit blocks, does not encourage software implementation but is much better suited for hardware implementation. However, by a series of equivalence transformations, all expansions and but two of the permutations can be eliminated. Furthermore, then the 16-bit or 32-bit architecture of modern microprocessors can be fully exploited. Both a 16-bit version of the transformed algorithm (for 8086 and 80286) and a 32-bit version (for 80386 and 80486) have been implemented in assembly language. Depending on the actual processor employed, the implementation chooses 16-bit code or 32-bit code at run time. A sustained throughput of over 75,000 bytes second on a 33-MHz 80386 with cache and of over 8800 bytes per second on a 10-MHz 80286 with one wait state is obtained. The program needs only 13·3 kbytes for code and data. Hence this high-performance software DES implementation is also well suited for embedded applications, as for instance for encryption of serial communication lines or ISDN voice and data channels.