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For mass surveillance, the algorithm substitution attacks (ASAs) are serious security threats to the symmetric encryption schemes. At CRYPTO 2014, Bellare, Paterson, and Rogaway (BPR) formally developed the security notions of decryptability, undetectability, and surveillance and presented a unique ciphertext symmetric encryption scheme against all possible ASAs. At FSE 2015, Degabriele, Farshim, and Poettering (DFP) relaxed the correctness of decryptability and presented an input-triggered ASA, which meets the BPR security definitions but violates the security of the BPR unique ciphertext scheme. Hence, DFP refined the security notions of detectability and subversion resistance to remove their ASA from the BPR unique ciphertext scheme. At CCS 2015, Bellare, Jaeger, and Kane (BJK) also developed the security notion of key recovery to make the input-triggered ASA infeasible. We investigate ASAs on the symmetric encryption scheme. Our contribution is twofold. (1) We propose a new trigger ASA against the symmetric encryption scheme . Our proposed ASA cannot be captured by the BJK security definitions. Comparatively, the DFP security definitions can detect our proposed ASA. In the view of ASAs, this result demonstrates that the DFP security definitions are not identical to the BJK security definitions. (2) We improve the DFP definition of subversion resistance . DFP proved that the BPR unique ciphertext scheme defeats the input-triggered ASA under their subversion resistance definition. However, we show that the BPR unique ciphertext scheme fails to meet the DFP subversion resistance definition due to our proposed ASA. Therefore, an improved definition on subversion resistance is proposed to cover all existing trigger ASAs. We prove that the BPR unique ciphertext scheme is secure under our improved definition. Therefore, we believe that our improved definition is more suitable to evaluate the ASA security of the symmetric encryption scheme.

Under the cloud computing environment, Searchable Symmetric Encryption (SSE) is an effective method to solve the problem of encrypted data retrieval, and helps to protect the users' privacy. Recent researches show that some attacks may bring great security threats to SSE, and forward privacy can effectively prevent these attacks, so forward privacy is very necessary for SSE scheme. Most of the existing forward privacy SSE schemes fall into two types: ORAM-based and Bost-based. The former is simple, but it has large communication overhead and low dynamic update efficiency. The latter is better than the former, but it is based on asymmetric encryption primitives. Based on symmetric encryption primitives, we propose a dynamic efficient forward privacy scheme DESSE in this paper. DESSE uses pseudo-random permutation to realize forward privacy, and uses delete list to identify the final state of the same file added and deleted repeatedly, so as to realize the dynamic update of data. The method proposed in this paper is simple and flexible in structure, takes up less additional space, and can significantly improve the efficiency of updating. At the same time, it can achieve real-time updating of data. The correctness of our proposed scheme is tested using the Enron email data set in the end.

The information technique has developed rapidly. The technique of QR codes is widely applied in our daily life, and the mechanism is suitable to share data. A QR code uses symmetric encryption to store and retrieve data efficiently. However, the security issues of QR codes are seldom discussed by the wider community. Moreover, if the sender wishes only the authorized participant to attain the private data which are shared, the data must be encrypted. Furthermore, we do not know who should be censured when problems arise. In view of this, to maintain the integrity and the confidentiality of information security, this paper proposed a new puzzle-based data sharing scheme to share the private information safely. Firstly, we generated the digital signature of the information, then applied the random grids algorithm to obtain the shares. Then, we disarrayed the shares which contain the information and the digital signature with a puzzle-based encoding method. Afterwards, we concealed them into the cover QR codes. With the QR code mechanism of error correction, the marked QR code remain meaningful. Finally, we could send marked QR codes via transmission. The receiver could use XOR operation to obtain the private information after solving the puzzles and verify whether it was tampered with by the digital signature. The proposed system can recover the lossless data and protect them from being divulged. To deal with the potential hazard of transmission in a public environment, there are more and more studies on data hiding and image authentication.

Modern communication networks can be flexibly shaped and controlled using Software Defined Networking (SDN) paradigm. However, besides unprecedented functional benefits, this solution exploits an architectural single point of failure. Securing the communication among SDN functional element is therefore a critical requirement for improving the network reliability. A novel approach to secure communications is provided by Quantum Key Distribution (QKD) that is a physical layer technology capable to securely deliver symmetric encryption keys leveraging on quantum physic properties. Our research demonstrates how to provide unconditionally secure communication at SDN level dramatically improving the reliability of the communication network itself.

International audience; In order to lower costs, the fabrication of Integrated Circuits (ICs) is increasingly delegated to offshore contract foundries, making them exposed to malicious modifications, known as hardware Trojans. Recent works have demonstrated that a strong form of Trojan-resilience can be obtained from untrusted chips by exploiting secret sharing and Multi-Party Computation (MPC), yet with significant cost overheads. In this paper, we study the possibility of building a symmetric cipher enabling similar guarantees in a more efficient manner. To reach this goal, we exploit a simple round structure mixing a modular multiplication and a multiplication with a binary matrix. Besides being motivated as a new block cipher design for Trojan resilience, our research also exposes the cryptographic properties of the modular multiplication, which is of independent interest.

Due to the rapidly growing number of devices that need to communicate securely, there is still significant interest in the development of efficient encryption schemes. It is important to maintain a portfolio of different constructions in order to enable a quick transition if a novel attack breaks a construction currently in use. A promising approach is to construct encryption schemes based on the learning parity with noise (LPN) problem as these schemes can typically be implemented fairly efficiently using mainly "exclusive or" (XOR) operations. Most LPN-based schemes in the literature are asymmetric, and there is no practical evaluation of any LPN-based symmetric encryption scheme. In this paper, we propose a novel LPN-based symmetric encryption scheme that is more efficient than related schemes. Apart from analyzing our scheme theoretically, we provide the first practical evaluation of a symmetric LPN-based scheme, including a study of its performance in terms of attainable throughput depending on the selected parameters. As the encryption scheme lends itself to an implementation in hardware, we further evaluate it on a low-end SoC FPGA. The measurement results attest that our encryption scheme achieves high performance rates in terms of throughput on such hardware, providing evidence that symmetric encryption schemes based on hard learning problems may be constructed that can compete with state-of-the-art encryption schemes.

A Shannon cipher can be used as a building block for the block cipher construction if it is considered as one data block cipher. It has been proved that a Shannon cipher based on a matrix power function (MPF) is perfectly secure. This property was obtained by the special selection of algebraic structures to define the MPF. In an earlier paper we demonstrated, that certain MPF can be treated as a conjectured one-way function. This property is important since finding the inverse of a one-way function is related to an N P -complete problem. The obtained results of perfect security on a theoretical level coincide with the N P -completeness notion due to the well known Yao theorem. The proposed cipher does not need multiple rounds for the encryption of one data block and hence can be effectively parallelized since operations with matrices allow this effective parallelization.

In this paper, an improved encryption algorithm based on numerical methods and rotation–translation equation is proposed. We develop the new encryption-decryption algorithm by using the concept of symmetric key instead of public key. Symmetric key algorithms use the same key for both encryption and decryption. Most symmetric key encryption algorithms use either block ciphers or stream ciphers. Our goal in this work is to improve an existing encryption algorithm by using a faster convergent iterative method, providing secure convergence of the corresponding numerical scheme, and improved security by a using rotation–translation formula.

Wearable devices are a part of Internet-of-Things (IoT) that may offer valuable data of their porting user. This paper explores the use of ElectroCardioGram (ECG) records to encrypt user data. Previous attempts have shown that ECG can be taken as a basis for key generation. However, these approaches do not consider time-invariant keys. This feature enables using these so-created keys for symmetrically encrypting data (e.g. smartphone pictures), enabling their decryption using the key derived from the current ECG readings. This paper addresses this challenge by proposing EbH, a mechanism for persistent key generation based on ECG. EbH produces seeds from which encryption keys are generated. Experimental results over 24 h for 199 users show that EbH, under certain settings, can produce permanent seeds (thus time-invariant keys) computed on-the-fly and different for each user up to 95.97% of users produce unique keys. In addition, EbH can be tuned to produce seeds of different length (up to 300 bits) and with variable min-entropy (up to 93.51). All this supports the workability of EbH in a real setting. (C) 2017 Elsevier B.V. All rights reserved. Funding: This work was supported by the MINECO grants TIN2013-46469-R (SPINY: Security and Privacy in the Internet of You) and TIN2016-79095-C2-2-R (SMOG-DEV); by the CAM grant S2013/ICE-3095 (CIBERDINE: Cybersecurity, Data, and Risks), which is co-funded by European Funds (FEDER); and by the Programa de Ayudas para la Movilidad of Carlos III University of Madrid, Spain (J. M. de Fuentes and L. Gonzalez-Manzano grants). Data used for this research was provided by the Telemetric and ECG Warehouse (THEW) of University of Rochester, NY.

This work introduces a new class of Algorithm Substitution Attack (ASA) on Symmetric Encryption Schemes. ASAs were introduced by Bellare, Paterson and Rogaway in light of revelations concerning mass surveillance. An ASA replaces an encryption scheme with a subverted version that aims to reveal information to an adversary engaged in mass surveillance, while remaining undetected by users. Previous work posited that a particular class of AEAD scheme (satisfying certain correctness and uniqueness properties) is resilient against subversion. Many if not all real-world constructions – such as GCM, CCM and OCB – are members of this class. Our results stand in opposition to those prior results. We present a potent ASA that generically applies to any AEAD scheme, is undetectable in all previous frameworks and which achieves successful exfiltration of user keys. We give even more efficient non-generic attacks against a selection of AEAD implementations that are most used in practice. In contrast to prior work, our new class of attack targets the decryption algorithm rather than encryption. We argue that this attack represents an attractive opportunity for a mass surveillance adversary. Our work serves to refine the ASA model and contributes to a series of papers that raises awareness and understanding about what is possible with ASAs.

Объектом исследования является разработка системы резервного копирования для электронного кошелька. В Ñ Ð¾Ð´Ðµ работы были изучены различные решения, подобраны различные алгоритмы и Ñ‚ÐµÑ Ð½Ð¾Ð»Ð¾Ð³Ð¸Ð¸, спроектирована и разработана собственная система резервного копирования. Результат дает пользователю возможность резервного копирования всего состояния приложения без Ð´Ð¾Ð¿Ð¾Ð»Ð½Ð¸Ñ‚ÐµÐ»ÑŒÐ½Ñ‹Ñ Ð´ÐµÐ¹ÑÑ‚Ð²Ð¸Ð¹., The object of the research is the development of a backup sys-tem for an electronic wallet. During the work, another solutions was investigated, special algorithms and technologies was selected, our own backup system was designed and developed. The result gives the user the ability to backup the entire state of the application without additional actions.

Preserving privacy of private communication against an attacker is a fundamental concern of computer science security. Unconditional encryption considers the case where an attacker has unlimited computational power, hence no complexity result can be relied upon for encryption. Optimality criteria are defined for the best possible encryption over a general collection of entropy measures. This paper introduces Apollonian cell encoders, a class of shared-key cryptosystems that are proven to be universally optimal. In addition to the highest possible security for the message, Apollonian cell encoders prove to have perfect secrecy on their key allowing unlimited key reuse. Conditions for the existence of Apollonian cell encoders are presented, as well as a constructive proof. Further, a compact representation of Apollonian cell encoders is presented, allowing for practical implementation.

Recent advancements in wireless technology have created an exponential rise in the number of connected devices leading to the internet of things (IoT) revolution. Large amounts of data are captured, processed and transmitted through the network by these embedded devices. Security of the transmitted data is a major area of concern in IoT networks. Numerous encryption algorithms have been proposed in these years to ensure security of transmitted data through the IoT network. Tiny encryption algorithm (TEA) is the most attractive among all, with its lower memory utilization and ease of implementation on both hardware and software scales. But one of the major issues of TEA and its numerous developed versions is the usage of the same key through all rounds of encryption, which yields a reduced security evident from the avalanche effect of the algorithm. Also, the encryption and decryption time for text is high, leading to lower efficiency in IoT networks with embedded devices. This paper proposes a novel tiny symmetric encryption algorithm (NTSA) which provides enhanced security for the transfer of text files through the IoT network by introducing additional key confusions dynamically for each round of encryption. Experiments are carried out to analyze the avalanche effect, encryption and decryption time of NTSA in an IoT network including embedded devices. The results show that the proposed NTSA algorithm is much more secure and efficient compared to state-of-the-art existing encryption algorithms.

International audience; Preserving the privacy of private communication is a fundamental concern of computing addressed by encryption. Information-theoretic reasoning models unconditional security where the strength of the results does not depend on computational hardness or unproven results. Usually the information leaked about the message by the ciphertext is used to measure the privacy of a communication , with perfect secrecy when the leakage is 0. However this is hard to achieve in practice. An alternative measure is the equivocation, intuitively the average number of message/key pairs that could have produced a given cipher-text. We show a theoretical bound on equivocation called max-equivocation and show that this generalizes perfect secrecy when achievable, and provides an alternative measure when perfect secrecy is not achievable. We derive bounds for max-equivocation for symmetric encoder functions and show that max-equivocation is achievable when the entropy of the ciphertext is minimized. We show that max-equivocation easily accounts for key re-use scenarios, and that large keys relative to the message perform very poorly under equivocation. We study encoders under this new perspective, deriving results on their achievable maximal equivocation and showing that some popular approaches such as Latin squares are not optimal. We show how unicity attacks can be naturally modeled, and how relaxing encoder symmetry improves equivocation. We present some algorithms for generating encryption functions that are practical and achieve 90 − 95% of the theoretical best, improving with larger message spaces.

Symmetric encryption is the most widely adopted security solution for wireless sensor networks. The main open issue in this context is represented by the establishment of symmetric keys. Although many key management schemes have been proposed in order to guarantee a high security level, a solution without weaknesses does not yet exist. An important class of key management schemes is based on a transitory master key (MK). In this approach, a global secret is used during the initialization phase to generate pair-wise keys, and it is deleted during the working phase. However, if an adversary compromises a node before the deletion of the MK, the security of the whole network is compromised. In this paper, a new key negotiation routine is proposed. The new routine is integrated with a well-known key computation mechanism based on a transitory master secret. The goal of the proposed approach is to reduce the time required for the initialization phase, thus reducing the probability that the master secret is compromised. This goal is achieved by splitting the initialization phase in hierarchical subphases with an increasing level of security. An experimental analysis demonstrates that the proposed scheme provides a significant reduction in the time required before deleting the transitory secret material, thus increasing the overall security level. Moreover, the proposed scheme allows to add new nodes after the first deployment with a suited routine able to complete the key establishment in the same time as for the initial deployment.

Healthcare remote devices are recognized as a promising technology for treating health related issues. Among them are the wireless Implantable Medical Devices (IMDs): These electronic devices are manufactured to treat, monitor, support or replace defected vital organs while being implanted in the human body. Thus, they play a critical role in healing and even saving lives. Current IMDs research trends concentrate on their medical reliability. However, deploying wireless technology in such applications without considering security measures may offer adversaries an easy way to compromise them. With the aim to secure these devices, we explore a new scheme that creates symmetric encryption keys to encrypt the wireless communication portion. We will rely on chaotic systems to obtain a synchronized Pseudo-Random key. The latter will be generated separately in the system in such a way that avoids a wireless key exchange, thus protecting patients from the key theft. Once the key is defined, a simple encryption system that we propose in this paper will be used. We analyze the performance of this system from a cryptographic point of view to ensure that it offers a better safety and protection for patients. 2018 by the authors. Acknowledgments: This publication was made possible by NPRP grant #8-408-2-172 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. Scopus

Current capabilities of smart cards, Smartphones, and cellular network provoke companies to provide vast amount of services to the mobile users. Some of those services require end-to-end encryption between a Service Provider and a SIM card. Keyed SIM cards already contain the required structure for secure key generation and upload, whereas un-keyed SIM cards do not have the required capability for this. In this paper, we provide a key exchange protocol, which creates a symmetric key by the collaborative work of SIM card and the Service Provider server. After a successful protocol run, SIM card and Service Provider can perform end-to-end data encryption. Publisher's Version

International audience; In the paper, we study whether it is possible to construct an efficient leakage-resilient symmetric scheme using the AES block cipher. We aim at bridging the gap between the theoretical leakage-resilient symmetric primitives used to build encryption schemes and the prac-tical schemes that do not have any security proof against side-channel adversaries. Our goal is to construct an as efficient as possible leakage-resilient encryption scheme, but we do not want to change the crypto-graphic schemes already implemented. The basic idea consists in adding a leakage-resilient re-keying scheme on top of the encryption scheme and has been already suggested by Kocher to thwart differential power analy-sis techniques. Indeed, in such analysis, the adversary queries the encryp-tion box and from the knowledge of the plaintext/ciphertext, she can per-form a divide-and-conquer key recovery attack. The method consisting in changing the key for each or after a small number of encryption with the same key is known as re-keying. It prevents DPA adversaries but not SPA attacks which uses one single leakage trace. Here, we prove that using a leakage-resilient re-keying scheme on top of a secure encryption scheme in the standard model, leads to a leakage-resilient encryption scheme. The main advantage of the AES block cipher is that its implementations are generally heuristically-secure against SPA adversaries. This assump-tion is used in many concrete instantiations of leakage-resilient symmet-ric primitives. Consequently, if we use it and change the key for each new message block, the adversary will not be able to recover any key if the re-keying scheme is leakage-resilient. There is mainly two different techniques for re-keying scheme, either parallel or sequential, but if we want to avoid the adversary having access to many inputs/outputs, only the sequential method is possible. However, the main drawback of the latter technique is that in case of de-synchronization, many useless com-putations are required. In our re-keying scheme, we use ideas from the skip-list data structure to efficiently recover a specific key. Full version of the paper published in the proceedings of CHES 2013.

Part 2: Workshop; International audience; Currently, electronic documents are commonly exchanged between/among government offices in many countries. When a government office would like to transmit a high-security-level-electronic document to another office, the sending end officer needs to encrypt it so as to protect the document from being known to hackers. AES and DES have been commonly and widely invoked to protect documents in recent years. However, the two algorithms have so far faced the threats of Brute-Force cracks. To avoid the threats, in this study, we proposed a new data encryption approach, called the Secure Data Encryption Method (SeDEM for short), in which plaintext and system keys are encrypted by using a sequential-logic style encryption approach which further employs a three-dimensional operation and a feedback encryption mechanism to effectively protect encrypted data from brute-force and cryptanalysis attacks. The feedback encryption mechanism is a feedback process in which each of its calculation iteration generates three internally-used dynamic feedback keys for the next calculation iteration. The purpose is to effectively improve the security level and unpredictability of generated ciphertext. The three-dimensional operation is employed to further increase the computational complexity of the encryption technique so as to enhance the security level of the ciphertext, and difficulty of cracking the keys.

This thesis looked at three encryption applications that all use the symmetric encryption algorithms AES, Twofish and Serpent but differ in their implementation and how this difference would illustrate itself in performance benchmarks depending on the type of storage device that they were used on. Three mechanical hard drives and one solid state drive were used in the performance benchmarks which measured a variety of different disk operations across the three encryption applications and their algorithms. From the benchmarks performance charts were produced which showed that DiskCryptor had the best performance when using a solid state drive and that TrueCrypt had the best performance when using mechanical hard drives. By choosing DiskCryptor as the encryption application when using a solid state drive a performance increase of 38.9% compared to BestCrypt and 28.4% compared to TrueCrypt was achieve when using the AES algorithm. It was also shown that Twofish was overall the best performing algorithm. The primary conclusion that can be drawn from this thesis is that it is important to choose the right encryption application depending on the type of storage device used in order to get the best performance possible.

Data security is of utmost importance in today's world. Especially when the data is travelling through an insecure communication network. There are symmetric key encryption techniques which use only one key for both encryption and decryption of the data. They are simple in design but can be easily cracked using brute force attacks. The entire security of such a cipher could be compromised if the attacker anyhow gets access to the keys. On the other hand, there are asymmetric key based algorithms which use a pair of keys, one for encryption, and the other for decryption, whose security is higher as compared to the symmetric ones but lack in time efficiency. It is also difficult to manage such a huge base of key-pairs efficiently and safely. This paper mainly focusses on the implementation of a system capable of encryption and decryption of multimedia data (Text, Images, Videos, Audio etc.) using a hybrid model based on the amalgamation of symmetric encryption techniques such as AES and asymmetric techniques such as ECC. ECC is based on the toughness of the discrete logarithm problem (DLP), whose public key is short, network bandwidth is little and ability to resist to attack is strong which makes it really difficult to guess the keys. Even if the attacker gets access to any of the keys, he or she won’t be in a position to decipher it in a relatively finite amount of man-years.