Ciphertext Block Research Articles

Perancangan Aplikasi Kriptografi Asimetris Dengan Menerapkan Metode Elliptic Curve Cryptography

Cryptography is one of the sciences used to maintain confidentiality and data security has been developing since ancient Greece. One cryptographic method that is quite reliable, stable and the parent of the popular cryptographic algorithms today is Elliptic Curve Cryptography (ECC). In this case the previous block encryption results are feedback into current block encryption. The trick, the current plaintext block is XORed first with the ciphertext block from the previous encryption, then the XOR results are entered into the encryption function. With ECC mode, each ciphertext block depends not only on the plaintext block but also on the all previous plaintext blocks, Implementation of the Elliptic Curve Cryptography (ECC) algorithm in this study was carried out by using an application built using visual basic programming language. Net 2008..

Beetle Family of Lightweight and Secure Authenticated Encryption Ciphers

This paper presents a lightweight, sponge-based authenticated encryption (AE) family called Beetle. When instantiated with the PHOTON permutation from CRYPTO 2011, Beetle achieves the smallest footprint—consuming only a few more than 600 LUTs on FPGA while maintaining 64-bit security. This figure is significantly smaller than all known lightweight AE candidates which consume more than 1,000 LUTs, including the latest COFB-AES from CHES 2017. In order to realize such small hardware implementation, we equip Beetle with an “extremely tight” bound of security. The trick is to use combined feedback to create a difference between the cipher text block and the rate part of the next feedback (in traditional sponge these two values are the same). Then we are able to show that Beetle is provably secure up to min{c − log r, b/2, r} bits, where b is the permutation size and r and c are parameters called rate and capacity, respectively. The tight security bound allows us to select the smallest security parameters, which in turn result in the smallest footprint.

Pseudo-probabilistic block ciphers and their randomization

There is considered implementation of the plan-ahead share-key deniable encryption algorithms that produce the cryptogram that satisfy criterion of the computational indistinguishability from probabilistic encryption of the fake message. This paper introduces a general design of the pseudo-probabilistic block ciphers. The proposed method includes encryption of the secret message block and the fake message block followed by a transformation procedure mapping the pair of intermediate ciphertext blocks into a single block of the output ciphertext. The transformation procedure is implemented in the following two variants: (1) simultaneous encryption of the intermediate ciphertext blocks and (2) solving the system of two linear congruencies. The second variant provides natural possibility to construct pseudo-probabilistic block ciphers in which recovering fake or secret message is performed using the same single decryption algorithm. To provide higher security there are proposed randomized pseudo-probabilistic ciphers. There are also considered designs with different size of the input data blocks corresponding to fake and secret messages.

A Survey on Confidential Cloud Data under Secure Key Exposure

Latest records display a effective attacker which breaks facts confidentiality with the resource of obtaining cryptographic keys, by using the usage of way of coercion or backdoors in cryptographic software program. As soon as the encryption secrets uncovered, the only possible diploma to maintain information confidentiality is to restrict the attacker’s access to the ciphertext. This can be finished, as an instance, with the resource of spreading ciphertext blocks in the course of servers in a couple of administrative domain names, therefore assuming that the adversary cannot compromise them all. However, if data is encrypted with present schemes, an adversary prepared with the encryption key, can nevertheless compromise an unmarried server and decrypt the ciphertext blocks saved therein. On this paper, we observe records confidentiality in opposition to an adversary which knows the encryption key and has get admission to a massive fraction of the ciphertext blocks. To this quit, we advise Bastion, a singular and green scheme that ensures data confidentiality notwithstanding the reality that the encryption secrets leaked and the adversary has access to nearly all ciphertext blocks. We analyze the security of Bastion, and we examine its standard overall performance via manner of a prototype implementation. We also talk realistic insights with admire to the combination of Bastion in business dispersed garage structures. Our evaluation results endorse that Bastion is well-applicable for integration in existing structures since it incurs less than 5% overhead compared to existing semantically relaxed encryption modes.

A parallel time-memory tradeoff attack on the Hill cipher

ABSTRACTLeap et al. (2016) reduced the time complexity of the Bauer-Millward (2007) ciphertext-only attack on the Hill cipher from 𝒪(Ln) to 𝒪(Ln−1), where L is the length of the alphabet, and n is the block size. This article presents an attack that reduces the complexity to 𝒪(Ln−1−s), 0 ≤ s ≤ n − 1. The practical limitation on the size of s is the memory available on the computer being used for the attack. Specifically, the computer must be able to hold Ls integer arrays of length N, where N is the number of blocks of ciphertext. The key idea is not to iterate over potential rows of the decryption matrix, but to iterate over randomly chosen characters in the plaintext. This attack also admits a straightforward parallel implementation on multiple processors to further decrease the run time of the attack.

Silicon Demonstration of Hardware Trojan Design and Detection in Wireless Cryptographic ICs

Using silicon measurements from 40 chips fabricated in Taiwan Semiconductor Manufacturing Company’s (TSMC’s) 0.35- $\mu \text{m}$ technology, we demonstrate the operation of two hardware Trojans, which leak the secret key of a wireless cryptographic integrated circuit (IC) consisting of an Advanced Encryption Standard (AES) core and an ultrawideband (UWB) transmitter (TX). With their impact carefully hidden in the transmission specification margins allowed for process variations, these hardware Trojans cannot be detected by production testing methods of either the digital or the analog part of the IC and do not violate the transmission protocol or any system-level specifications. Nevertheless, the informed adversary, who knows what to look for in the transmission power waveform, is capable of retrieving the 128-bit AES key, which is leaked with every 128-bit ciphertext block sent by the UWB TX. Moreover, through physical measurements and MATLAB simulations, we show that the attack facilitated by these hardware Trojans is robust to test equipment and communication channel noise. Finally, we experimentally evaluate the effectiveness of a popular hardware Trojan detection method, namely, statistical side-channel fingerprinting via trained one-class classifiers, in detecting the hardware Trojans introduced in our fabricated IC population.

Linking Online Misuse-Resistant Authenticated Encryption and Blockwise Attack Models

Real-world applications of authenticated encryption often require the encryption to be computable online, e.g. to compute the i th block of ciphertext after having processed the first i blocks of plaintext. A significant line of research was dedicated to identifying security notions for online authenticated encryption schemes, that capture various security goals related to real-life scenarios. Fouque, Joux, Martinet and Valette proposed definitions of privacy and integrity against adversaries that can query their oracles in a blockwise-adaptive manner, to model memory-constrained applications. A decade later, Fleischmann, Forler and Lucks proposed the notion of online nonce misuse-resistant authenticated encryption (OAE) to capture the security of online authenticated encryption under nonce-reuse. In this work we investigate the relation between these notions. We first recast the blockwise notions of Fouque et al. to make them compatible with online authenticated encryption schemes that support headers. We then show that OAE and the conjunction of the blockwise notions are “almost” equivalent. We identify the missing property on the side of blockwise notions, and formalize it under the name PR-TAG. With PR-TAG being just an auxiliary definition, the equivalence we finally show suggests that OAE and the blockwise model for online authenticated encryption capture essentially the same notion of security.

Linking Online Misuse-Resistant Authenticated Encryption and Blockwise Attack Models

Real-world applications of authenticated encryption often require the encryption to be computable online, e.g. to compute the ith block of ciphertext after having processed the first i blocks of plaintext. A significant line of research was dedicated to identifying security notions for online authenticated encryption schemes, that capture various security goals related to real-life scenarios. Fouque, Joux, Martinet and Valette proposed definitions of privacy and integrity against adversaries that can query their oracles in a blockwise-adaptive manner, to model memory-constrained applications. A decade later, Fleischmann, Forler and Lucks proposed the notion of online nonce misuse-resistant authenticated encryption (OAE) to capture the security of online authenticated encryption under nonce-reuse. In this work we investigate the relation between these notions. We first recast the blockwise notions of Fouque et al. to make them compatible with online authenticated encryption schemes that support headers. We then show that OAE and the conjunction of the blockwise notions are “almost” equivalent. We identify the missing property on the side of blockwise notions, and formalize it under the name PR-TAG. With PR-TAG being just an auxiliary definition, the equivalence we finally show suggests that OAE and the blockwise model for online authenticated encryption capture essentially the same notion of security.

Proposed Framework for Online Transaction using NPN Encryption Algorithm

While traversing, the history observed few ways of ensuring security when data is transmitted through some unsecured path. One such way is cryptography which is being used for centuries for securing the information. Symmetric key encryption algorithm uses one single key to send and receive the data, which means the sender and receiver share the unique key, known only to those two parties involved in the transaction. Stream cipher and block cipher are two ways to implement the symmetric key algorithm. Stream cipher plays with individual bits along with the key, whereas block of plaintext is given as an input for processing, and finally, a block of ciphertext is retrieved. This research paper highlights the most desirable properties like avalanche effect, completeness and statistical independence of a symmetric key block cipher. This article depicts that the block cipher algorithm should possess the features mentioned above as very basic to ensure security. The paper also sheds light on nth Prime Number (NPN) algorithm by illustrating the features above. It also shows a basic comparative analysis of existing algorithms like Data Encryption Standard, Advanced Encryption Standard by avalanche effect. This paper also proposed a framework for NPN, and where NPN can be implemented in real life.

A Stream Encryption Scheme with Both Key and Plaintext Avalanche Effects for Designing Chaos-Based Pseudorandom Number Generator with Application to Image Encryption

Based on a stream encryption scheme with avalanche effect (SESAE), a stream encryption scheme with both key avalanche effect and plaintext avalanche effect (SESKPAE) is introduced. Using this scheme and an ideal [Formula: see text]-word ([Formula: see text]-segment) pseudorandom number generator (PRNG), a plaintext can be encrypted such that each bit of the ciphertext block has a change with the probable probability of [Formula: see text] when any word of the key is changed or any bit of the plaintext is changed. To that end, a novel four-dimensional discrete chaotic system (4DDCS) is proposed. Combining the 4DDCS with a generalized synchronization (GS) theorem, a novel eight-dimensional discrete GS chaotic system (8DDGSCS) is constructed. Using the 8DDGSCS, a [Formula: see text]-word chaotic pseudorandom number generator (CPRNG) is designed. The keyspace of the [Formula: see text]-word CPRNG is larger than [Formula: see text]. Then, the FIPS 140-2 test suit/generalized FIPS 140-2 test suit is used to test the randomness of the 1000-key streams consisting of 20[Formula: see text]000 bits generated by the [Formula: see text]-word CPRNG, the RC4 algorithm PRNG and the ZUC algorithm PRNG, respectively. The test results show that for the three PRNGs, there are 100%/98.9%, 99.9%/98.8%, 100%/97.9% key streams passing the tests, respectively. Furthermore, the SP800-22 test suite is used to test the randomness of four 100-key streams consisting of 1000[Formula: see text]000 bits generated by four PRNGs, respectively. The numerical results show that the randomness performances of the [Formula: see text]-word CPRNG is promising, showing that there are no significant correlations between the key streams and the perturbed key streams generated via the [Formula: see text]-word CPRNG. Finally, using the [Formula: see text]-word CPRNG and the SESKPAE to encrypt two gray-scale images, test results demonstrate that the [Formula: see text]-word CPRNG is able to generate both key avalanche effect and plaintext avalanche effect, which are similar to those generated via an ideal CPRNG, and performs better than other comparable schemes.

Cryptanalysis of a secure chaotic map based block cryptosystem with application to camera sensor networks

Recently, a block cryptosystem based on iterating a chaotic map is analyzed and improved. But still four security flaws in this improved cryptosystem have been identified with careful analysis. First, the first block of ciphertext is identical to the corresponding plaintext in special circumstances. Second, an important parameter can be obtained with a chosen ciphertext attack. Third, with this parameter, a known block of ciphertext, and the corresponding block of plaintext, a block of plaintext can be recovered by chosen ciphertext attack. Forth, the relationship between every two blocks of the keystream can be determined, leading to the recovery of the entire keystream if a single block of the keystream can be obtained. Those four security flaws render the cryptosystem insecure for general use.

Almost universal forgery attacks on AES-based MAC’s

A message authentication code (MAC) computes for each (arbitrarily long) message $$m$$m and key $$k$$k a short authentication tag which is hard to forge when $$k$$k is unknown. One of the most popular ways to process $$m$$m in such a scheme is to use some variant of AES in CBC mode, and to derive the tag from the final ciphertext block. In this paper, we analyze the security of several proposals of this type, and show that they are vulnerable to a new type of attack which we call almost universal forgery, in which it is easy to generate the correct tag of any given message if the attacker is allowed to change a single block in it.

CBC and Interleaved CBC Implementations of PACTS Cryptographic Algorithm

PACTS (Parallelized Adaptive Cipher with Transposition and Substitution) is a new class of Symmetric Cryptographic Algorithm designed using traditional techniques to efficiently utilize the parallel computing capabilities of the modern computing systems. It overcomes the performance inconsistencies prevalent in conventional cryptographic algorithms when they are implemented in different computing systems with different processing capabilities. The size of the key and the plain text blocks of PACTS are each 1024-bits. The adaptive nature of this algorithm is achieved by incorporating flexibility in the size of the key and plain text sub-blocks and the number of rounds. Level of Intra-packet parallelization, variety in grain size and the required security strength are achieved by suitably deciding the sub-block size. Flow of the algorithm is made dynamic by determining the execution steps at runtime using the value of the key. In spite of these advantages PACTS always produces the same cipher text block for a particular plain text block when the same key is used. CBC mode along with 2- way and 4 way Interleaved CBC modes are employed to overcome this problem. The performance of the PACTS in ECB, CBC and Interleaved CBC modes are analyzed with implementations in shared memory parallel computing environment using Open MP, Java Threads and MPI.

Data based Transposition to Enhance Data Avalanche and Differential Data Propagation in Advanced Encryption Standard

In symmetric block ciphers, substitution and transposition operations are performed in multiple rounds to transform plaintext blocks into ciphertext blocks. In advanced Encryption Standard (AES) the transposition of data is facilitated by shift row and mix column operations. In Matrix Array Symmetric Key (MASK) Encryption, a block cipher proposed by the author, the data transposition is achieved by data based rotations. The data based transposition procedure offers two advantages. First, it is simple to implement and secondly, the procedure produces a strong data avalanche effect and differential data propagation. In this paper the possibility of improvising the performance of AES using data based transposition in its diffusion rounds is examined. As a case study, the data based transposition procedure has been introduced in AES. The data avalanche and differential data propagation produced in AES have been observed. The paper describes the data based transposition procedure and the enhanced data avalanche and differential data propagation produced in AES. It has been shown that, the data avalanche effect and differential data propagation characteristics of AES have been improved. General Terms Encryption Algorithm, Diffusion Round, Symmetric Block Cipher, Cryptographic Transformation.

A hill cipher‐based remote data possession checking in cloud storage

ABSTRACTCloud storage enables users to access their data at any time anywhere. It has the advantages of high scalability, ease of use, cost effectiveness, and so on. However, the server that stores users' data may not be fully trustworthy. When users store their data in cloud storage, they concern much about data intactness. This is the goal of remote data possession checking schemes. This paper proposes a Hill cipher‐based remote data possession checking scheme. The main idea of the scheme comes from the homomorphism of Hill cipher, namely the tags computed from plaintext blocks can be used to compare with the tags computed from ciphertext blocks. It has several advantages as follows. First, it is efficient in terms of computation and communication. Second, it allows verification without the need for the challenger to compare against the original data. Third, the scheme only needs to store a small amount of metadata and use only small challenges and responses. Finally, it performs data possession checking at the same time it provides confidentiality of data. The security and performance analysis illustrates that the scheme is feasible and effective. Copyright © 2013 John Wiley & Sons, Ltd.

Multilayer Perceptron Guided Key Generation through Mutation with Recursive Replacement in Wireless Communication (MLPKG)

In this paper, a multilayer perceptron guided key generation for encryption/decryption (MLPKG) has been proposed through recursive replacement using mutated character code generation for wireless communication of data/information. Multilayer perceptron transmitting systems at both ends accept an identical input vector, generate an output bit and the network are trained based on the output bit which is used to form a protected variable length secret-key. For each session, different hidden layer of multilayer neural network is selected randomly and weights or hidden units of this selected hidden layer help to form a secret session key. The plain text is encrypted using mutated character code table. Intermediate cipher text is yet again encrypted through recursive replacement technique to from next intermediate encrypted text which is again encrypted to form the final cipher text through chaining, cascaded xoring of multilayer perceptron generated session key. If size of the final block of intermediate cipher text is less than the size of the key then this block is kept unaltered. Receiver will use identical multilayer perceptron generated session key for performing deciphering process for getting the recursive replacement encrypted cipher text and then mutated character code table is used for decoding. Parametric tests have been done and results are compared in terms of Chi-Square test, response time in transmission with some existing classical techniques, which shows comparable results for the proposed technique.

Measuring Diffusion in Stream Ciphers using Statistical Testing Methods

Confusion and diffusion suggested by Claude Shannon are two techniques that symmetric key ciphers should satisfy to prevent cryptanalysis. Diffusion dissipates the statistical properties of the plaintext over the whole ciphertext. For a block cipher, each bit of the output ciphertext block changes with probability one half for any flipped bit in the input plaintext block, implying the cipher to have good diffusion properties. This definition with slight modification can also be applied to stream ciphers but here it is enough to make sure the following: (i) to ensure an overall change in the output keystream with probability half for any flipped bit in the Key-IV bit sequence, and (ii) to verify that every bit in the output keystream changes with probability one half for any single bit flip in the key-IV bit sequence. Here we insist on using these tests together for measuring diffusion in stream ciphers. Based on this we have examined the level of diffusion exhibited by some of the eSTREAM candidates and the result is given in this paper. Defence Science Journal, 2012, 62(1), pp.6 -10 , DOI:http://dx.doi.org/10.14429/dsj. 62.1435

A Novel Enhancement Technique of the Hill Cipher for Effective Cryptographic Purposes

Problem statement: The Hill cipher is the first polygraph cipher which has a few advantages in data encryption. However, it is vulnerable to known plaintext attack. Besides, an invertible key matrix is needed for decryption. It may become problematic since an invertible key matrix does not always exist. Approach: In this study, a robust Hill algorithm (Hill++) has been proposed. The algorithm is an extension of Affine Hill cipher. A random matrix key, RMK is introduced as an extra key for encryption. An algorithm proposed for involutory key matrix generation is also implemented in the proposed algorithm. Results: A comparative study has been made between the proposed algorithm and the existing algorithms. The encryption quality of the proposed algorithm is also measured by using the maximum deviation factor and correlation coefficient factor. Conclusion/Recommendations: The proposed algorithm introduced a random matrix key which is computed based on the previous ciphertext blocks and a multiplying factor. A modified of Hill Cipher is free from the all-zero plaintext blocks vulnerability. Usage of involutory key for encryption and decryption managed to solve the non invertible key matrix problem. It also simplify the computational complexity in term of generating the inverse key matrix.

Information Protection Based on Extraction of Square Roots of Gaussian Integers

A cryptosystem based on computation of square roots of complex integers modulo composite n is described in this paper. This paper provides an algorithm extracting a square root of Gaussian integer. Various properties of square roots and a method for finding Gaussian generators are demonstrated. The generators can be instrumental in constructing other cryptosystems. It is shown how to significantly reduce average complexity of decryption per each block of ciphertext.

COUNTER MODE DEVELOPMENT FOR BLOCK CIPHER OPERATIONS

There are two basic types of symmetric cipher: block ciphers and stream ciphers. Block ciphers operate on blocks of plaintext and ciphertext—usually of 64 bits but sometimes longer. Stream ciphers operate on streams of plaintext and ciphertext one bit or byte (sometimes even one 32-bit word) at a time. The Block cipher modes of operation can be applied as both stream and block cipher.In this paper we introduce three developments of Counter Mode of Operation of Block cipher. These developments merge between advantages of Counter Mode with other Modes. This gives a good secure Modes for General purpose block-oriented transmission Authentication, Random access, Stream-oriented transmission over noisy channel.