Stream Cipher Research Articles

RAPP: Reversible Privacy Preservation for Various Face Attributes

The tremendous progress in deep learning has enabled to extract soft-biometric attributes from faces, which raises privacy concerns over images collected for face recognition. Advances toward attribute privacy have been able to conceal multiple attributes while preserving identity information but suffer from limitations: they 1) only consider a few soft-biometric attributes and 2) fail to support reversibility for attribute privacy preservation. To break these limitations, we design a reversible privacy-preserving scheme for various face attributes, called reversible attribute privacy preservation (RAPP). RAPP benefits from two modules: 1) The attribute obfuscator introduces a stream cipher to determine that special attributes have to be concealed with the user-defined password, which also supports recovering original attributes. 2) The attribute adversarial network is proposed to generate perturbed images that conceal various attributes while retaining the utility of face verification. In addition, when a wrong password is provided, the returned image with wrong attribute classification results still keeps realistic, which confuses an attacker to know whether the recovery is correct. Extensive experiments demonstrate that RAPP enables to conceal various attributes and recover original images while facilitating face verification.

Extended-Chacha20 Stream Cipher With Enhanced Quarter Round Function

Extended-Chacha20 Stream Cipher With Enhanced Quarter Round Function

A Robust Selective Encryption Scheme for H.265/HEVC Video

To protect the information of video stream, many selective video encryption schemes have been proposed based on the H.265/HEVC video. However, most of the existing algorithms are not robust, thus failing to decrypt under packet loss. To further improve the robustness capability of video protection, a robust selective encryption scheme is proposed in this paper. In H.265/HEVC standard, video is encoded into multiple slices, and the slices are decoded independently. Inspired by the feature, each slice is individually encrypted using RC4 stream cipher. The pseudorandom binary sequence (PRBS) for one slice is related to encoding parameters and the SHA-256 hash value of the corresponding slice header, thus ensuring the real-time update of the PRBS and increasing the resistance to chosen-plaintext attack. Two-rounds shifting algorithm is designed to scramble non-zero coefficients of the transform units (TUs) and then motion vector difference (MVD) parameters, quantized transform coefficients (QTCs) and intra prediction modes (IPMs) are selected for encryption. The combination of coefficient scrambling and syntax elements encryption further improves the encryption performance. The proposed scheme is slice-synchronized. Hence, it decrypts normally in the case of packet loss, and supports online real-time interaction. Furthermore, the simulation and analysis results show that the proposed algorithm has format compatibility, high security and low time complexity, which is a promising tool for video cryptographic applications.

A Novel Stream Cipher Based on Quasigroups and QG-PRNG

A Novel Stream Cipher Based on Quasigroups and QG-PRNG

A novel stream cipher based on quasigroups and QG-PRNG

A novel stream cipher based on quasigroups and QG-PRNG

Nonsingularity of Trivium-like cascade FSRs over finite fields via semi-tensor product

In stream cipher designing, nonsingularity is a crucial requirement to ensure that the feedback shift registers (FSRs) do not produce keys that are equivalent to one another. This study uses a semi-tensor product to examine the nonsingularity of Trivium-like cascade FSRs over a finite field. The Trivium-like cascade FSRs are expressed algebraically using the semi-tensor product, allowing them to be viewed as logical networks and introducing a novel state transition matrix. Several necessary and sufficient conditions for the nonsingularity of FSRs and Trivium-like cascade FSRs over a finite field are established by dividing the structural matrices of feedback functions into different parts. These findings are also applicable to binary FSRs and binary Trivium-like cascade FSRs.

On Resilient Boolean and Vectorial Boolean Functions with High Nonlinearity

Boolean functions and vectorial Boolean functions are the most important nonlinear components of stream ciphers. They should satisfy several criteria such as high nonlinearity, proper resiliency and so on to guarantee the security of the whole system. However, there are some constraints among the criteria, and how to achieve a trade-off between them is an important issue. In this paper, some nonlinear Boolean functions possessing simple algebraic normal form with special Walsh spectrum are proposed. By using these functions, we provide two construction methods on balanced and resilient Boolean functions with high nonlinearity. In addition, based on the disjoint linear codes and vector matrices with special properties, some resilient vectorial Boolean functions with currently best-known nonlinearity have also been given.

Robust timing and frequency joint synchronization method for QNSC-enabled security optical communications system based on CO-OFDM

The security of optical fiber communication network has been paid more and more attention, and Quantum Noise Stream Cipher (QNSC) can guarantee its physical layer security. However, the QNSC system realized with CO-OFDM technology is very susceptible to timing synchronization error and carrier frequency offset. Existing symbol timing and frequency synchronization algorithms based on preambles have problems of timing metric platform, interference of side lobes, and low timing and frequency synchronization accuracy especially in optical signal transmission scenario of high-order modulation and low SNR. Furthermore, the preamble is not encrypted, which can be easily identified by illegal receiver. In order to solve above problems, a robust timing and frequency joint synchronization algorithm is proposed. The algorithm is composed of the preamble interleaved by conjugate, negative and image sequences of original element sequence. The preamble conforms to the preamble structure of Schmidl, Minn and CNI by adding negative and conjugate operator at the specific interval of the preamble. The correspond timing metric method, i.e. combination of Schmidl, Minn and CNI timing metric strategies, can fully extract characteristics of the preamble, and then timing and frequency joint synchronization is accurately obtained. For timing synchronization, experiments in 10Gbit/s CO-OFDM based QNSC system have illustrated that proposed algorithm has better timing synchronization performance than baseline algorithms. The detection probability is augmented and timing offset mean is decreased than that of baseline algorithms especially at low SNR. The simulation illustrates that proposed algorithm has more accurate frequency offset (FO) estimation performance compared with the baseline algorithms even at low SNR. Furthermore, the simulation illustrates the security performance of CO-OFDM based QNSC system is improved by encrypting the preamble with secret key.

Quantum Guess and Determine Attack on Stream Ciphers

Abstract To guarantee the security of symmetric key schemes against quantum adversary, developing quantum cryptanalytic techniques becomes a major worldwide challenge in the post-quantum world. In this paper, we present a general framework of classical guess and determine attack on stream ciphers, and then convert it into quantum guess and determine attack. It shows that, for a given stream cipher with a key size of $k$ bits and an internal state size of $n$ bits, if a basic guess and determine attack with a time complexity below $O ( {{{2}^{{3k}/{2}}}}/{n} )$ is available, there is a quantum guess and determine attack with multiple data that can recover all $n$ internal state bits of the cipher with complexity below $O ( {{2^{k / 2}}} )$. As applications, we present quantum guess and determine attacks on the SNOW-like stream ciphers. The results show that all of SNOW 1.0 with 128-bit key, SNOW 2.0 with 128-bit key and SOSEMANUK are insecure against quantum guess and determine attack. The resource requirements for implementing a quantum guess and determine attack on SNOW 3G are evaluated as a case study. To the best of our knowledge, this is the first time that the general quantum guess and determine attack is formally proposed and applied to the SNOW-like stream ciphers.

High-performance reversible data hiding in encrypted images with adaptive Huffman code

With the development of cloud computing, reversible data hiding in encrypted images (RDHEI) has attracted increasing attention. In this paper, a high-performance RDHEI algorithm with Adaptive Huffman Code (RDHEI-AHC) is proposed for cloud computing. First, multi-MSB (Most Significant Bit) of each pixel is predicted by geometric correction, which takes full advantage of spatial correlation. Next, the image is encrypted by stream cipher. Adaptive Huffman code is then used to insert the auxiliary information and secret message into the encrypted image. Finally, to resist ciphertext-only attacks, the marked encrypted image must be scrambled. In comparison to most state-of-the-art RDHEI approaches, experimental results show that the RDHEI-AHC method delivers a greater embedding rate and improved security.

Cryptanalysis of Draco

Draco is a lightweight stream cipher designed by Hamann et al. in IACR ToSC 2022. It has a Grain-like structure with two state registers of size 95 and 33 bits. In addition, the cipher uses a 128-bit secret key and a 96-bit IV. The first 32 bits of the key and the IV forms a non-volatile internal state that does not change during the time that the cipher produces keystream bits.The authors claim that the cipher is provably secure against Time-Memory-Data (TMD) Tradeoff attacks. However in this paper, we first present two TMD tradeoff attacks against Draco. Both attacks leverage the fact that for certain judiciously chosen IVs the state update function of the cipher depend on only a small fraction of the non-volatile internal state. This makes the state update function in Draco essentially a one way function over a much smaller domain and range. The first attack requires around 2114.2 Draco iterations and requires that the adversary has access to 232 chosen IVs. The second attack is such that the attack parameters can be tuned as per the requirements of the attacker. If the attacker prioritizes that the number of different chosen IVs is limited to 220 say, then the attack can be done in around time proportional to 2126 Draco rounds. However if the total attack complexity is to be optimized, then the attack can be performed in 2107 time using around 240 chosen IVs.

Pathway For a More Discrete Fintech Application

The addition of the Secure Hash Algorithm SHA-256, the Advanced Encryption Standard AES-128, and dynamic polynomialswitchingintheLinearFeedbackShiftRegistersenhancesthesecurityof stream cipher. Numerous studies concluded that this introduction strengthens the stream cipher's resistance to cryptanalysis. In order to provide a distinct understanding of these designs, this study intends to present a thorough assessment that highlights current attempts to put this concept into practice. The process of creating new designs will be aided by this vision.

An Attack on a Proposed Construction of Small-State Stream Ciphers and Proposals for New Constructions

Abstract Small-state stream ciphers (SSCs) idea is based on using key bits not only in the initialization but also continuously in the keystream generation phase. A time-memory-data tradeoff (TMDTO) distinguishing attack was successfully applied against all SSCs in 2017 by Hamann et al. They suggested using not only key bits but also initial value (IV) bits continuously in the keystream generation phase to strengthen SSCs against TMDTO attacks. Then, Hamann and Krause proposed a construction based on using only IV bits continuously in the packet mode. They suggested an instantiation of an SSC and claimed that it is resistant to TMDTO attacks. We point out that accessing IV bits imposes an overhead on cryptosystems that might be unacceptable in some applications. More importantly, we show that the proposed SSC remains vulnerable to TMDTO attacks 1. To resolve this security threat, the current paper proposes constructions based on storing key or IV bits that are the first to provide full security against TMDTO attacks. Five constructions are proposed for different applications by considering efficiency. Designers can obtain each construction’s minimum volatile state length according to the desirable keystream, key and IV lengths.

Improved differential attacks on the reduced-round SNOW-V and SNOW-Vi stream cipher

The SNOW-V stream cipher is a candidate cipher for 5G mobile communication system, and the SNOW-Vi stream cipher is a faster variant of SNOW-V. In this paper, we analyze the resistance of the reduced-round SNOW-V and SNOW-Vi against the chosen IV differential distinguishing attacks in the initialization phase. Firstly, we use the divide-and-conquer strategy to give a Mixed-integer Linear Programming (MILP) model to describe the probabilities within the Differential Distribution Table (DDT) of large S-boxes, which can more accurately search the best differential characteristics of SNOW-V and SNOW-Vi than using the probability lower bound of the DDT in the original MILP model. Secondly, we point out that the registers R1,R2,R3 of SNOW-Vi filled with 0 were not considered in the original MILP model, resulting in the MILP model may return impossible differential characteristics. Then, we give the splicing search technology of C program and MILP model to solve this problem. Thirdly, based on these two studies, we present a more efficient and accurate MILP model for searching the best differential characteristics of the reduced-round SNOW-V and SNOW-Vi. The improved MILP model reduces the complexity of the distinguishing attacks. Finally, we give two multiple differential attack techniques on SNOW-V/SNOW-Vi structure, and apply them to the reduced-round SNOW-V and SNOW-Vi, respectively. While improving the results of single differential attacks, we also reduce the complexity of differential attack on the 4-round SNOW-V from 297 to 259.985, which can give the effective attack under the data limitation 264 for the single key. In addition, we give the first differential attack on 5-round SNOW-Vi, and the time complexity and data complexity is 296.84. The success rate is 0.97725. Although this has exceeded the data complexity limitation of the single key attack, it is meaningful for us to analyze the security of SNOW-Vi.

Guess-and-determine attacks on SNOW-Vi stream cipher

Guess-and-determine attacks on SNOW-Vi stream cipher

Optimal Double Layer Secret Sharing Scheme for Biometrics

Visual secret sharing (VSS) method is an encryption method to ensure the Security of secret data, that just performs the partitioning of ‘n’ shares and distributes among ‘n’ users in an ideal way so that exposing of less than ‘n’ shares is of no utilization. However, some dishonest members or hackers team up and tries to cheat other members in the group. Therefore, we have developed a dual layer secret sharing scheme based on universal share based secret sharing scheme. The dual layer is composed of threshold based secret sharing and then followed by the universal share based secret sharing. Here, the universal share is maintained by the trusted party avoids the contribution of dishonest participants. Moreover, to ensure additional security, the proposed approach employs Oppositional Artificial Fish Swarm Optimization (OAFSO) based Stream Cipher encryption technique to encrypt the shares, shows the novelty of the work. Furthermore, the confidentiality is enhanced with Biometric fingerprint authentication step, where the acknowledged users are alone allowed to get the decrypt shares with that the user can retrieve the secret data. The proposed fingerprint authentication method also makes use of Secure Hash Algorithm (SHA 1) to store the fingerprints and the matching is also done with hashed fingerprints only. So that the attackers cannot take and corrupt the stored fingerprints and the misuse of fingerprints is not possible. Finally the performance analysis is made with existing approaches in terms of PSNR and MSE. Maximum PSNR is 58.9802 and minimum MSE value is 0.6232, while the existing methods provide very less PSNR and greater MSE values than the proposed methods.

A new idea in response to fast correlation attacks on small-state stream ciphers

In the conference “Fast Software Encryption 2015”, a new line of research was proposed by introducing the first small-state stream cipher (SSC). The goal was to design lightweight stream ciphers for hardware applications by going beyond the rule that the internal state size must be at least twice the intended security level. Fast correlation attack (FCA) was successfully applied to all proposed SSCs which can be implemented by less than 1000 gate equivalents in hardware. It is possible to increase the security of stream ciphers against FCA by exploiting more complicated functions for the nonlinear feedback shift register and the output function, but we use lightweight functions to design the lightest SSC in the world while providing more security against FCA. Our proposed cipher provides 80-bit security against all types of Time-memory-data trade-off (TMDTO) attacks, while Lizard and Plantlet provide only 60-bit and 58-bit security against TMDTO distinguishing attacks, respectively. Our main contribution is to propose a lightweight round key function with a very long period that increases the security of SSCs against FCA.

Improved Salsa20 Stream Cipher Diffusion Based on Random Chaotic Maps

To enhance stream ciphers, numerous studies have concentrated on the randomness, unpredictable nature, and complexity of keystream. Numerous stream algorithms have been put forth. Most of them require a significant amount of computational power. Salsa20 is a high-performance stream encryption solution that works on computers with fewer resources and uses a secure method that is faster than AES. They suggest Salsa20 for encryption in common cryptographic applications. Users who value speed over certainty should utilize the Salsa20 family of reduced-round ciphers, such as the (8,12) round cipher. It uses a 256-bit key and a hash algorithm. A successful fusion makes use of both the Salsa20 algorithm's and the random maps' advantages to improve the Salsa20 algorithm's shortcomings by increasing its unpredictability. Particularly now that Salsa20/7 has been hacked and Salsa20/12 is no longer as secure as it previously was. As a result, Salsa20 needs to achieve a high level of diffusion to withstand known attacks. Right now, salsa20 and its shortened versions rank among the fastest ciphers. This study presents a novel lightweight approach to construct a strong keystream that is sufficiently random to avoid being predicted by adversaries, achieve good diffusion, and withstand known assaults. A NIST test found that the performance of the (Salsa20-chaotic maps) approach in terms of data integrity and secrecy is nearly 0.3131 higher than that of the Salsa20 .

High Throughput Efficient Implementation of Grain v1, Lizard and Plantlet Stream Ciphers for Resource Constraint Devices

High Throughput Efficient Implementation of Grain v1, Lizard and Plantlet Stream Ciphers for Resource Constraint Devices

Proposed Hybrid Technique in Cryptanalysis of Cryptosystem Based on PSO and SA

Modern ciphers are one of the more difficult to break cipher systems because these ciphers high security, high speed, non - propagation error and difficulty in breaking it. One of the most important weaknesses of stream cipher is a matching or correlation between the output key-stream and the output of shift registers. This work considers new investigation methods for cryptanalysis stream cipher using ciphertext only attack depending on Particle Swarm Optimization (PSO) for the automatic extraction for the key. It also introduces a cryptanalysis system based on PSO with suggestion for enhancement of the performance of PSO, by using Simulated Annealing (SA). Additionally, it presents a comparison for the cryptanalysis system results that were obtained by the proposed technique, which is called Modified PSO (MPSO) with classical PSO and GA. These algorithms can be used for reducing the number of attempts or trials of key space, which are needed to reach to the optimal solution (the exact initial setting of Linear Feedback Shift Register (LFSR)),and increase the speed of the search process to find the best solution. Based on the obtained results, these algorithms were shown to be effective at finding the optimal solution and the MPSO method operates better compared with PSO in the term of time and accuracy. Well known stream cipher systems were attacked by the two soft computing methods as the cases of study, which are Geffe , Brȕer and Shrinking stream cipher systems.