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cryptography
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Leveled design of cryptography algorithms using cybernetic methods for using in telemedicine applications
, Article Computational Intelligence and Neuroscience ; Volume 2021 , 2021 ; 16875265 (ISSN) ; Aref, M. R ; Ramazani Khorshiddoust, R ; Sharif University of Technology
Hindawi Limited
2021
Abstract
The technology world is developing fast with the developments made in the hardware and software areas. Considering that privacy and security of telemedicine applications are among the main necessities of this industry, as a result, there is a need to use lightweight and practical algorithms to be used in applications in the field of telemedicine, while security have the least negative impact. The distinct and contradicting components in the design and implementation of the cryptography algorithm, to achieve various objectives in medicine-based applications, have made it a complicated system. It is natural that, without identifying the components, indices, and properties of each system...
Cryptographic Hash Functions from Expander Graphs
, M.Sc. Thesis Sharif University of Technology ; khazaei, Shahram (Supervisor)
Abstract
A hash function maps efficiently every finite length string to a fixed one. The output represents the entire content of the input, similar to digital fingerprint of input text. In order to be able to use a hash function in cryptography, it should be hard to find two distinct inputs with the same output (collision), because finding a collision in hash functions leads to malicious attacks on many security systems.We say a hash function is provably collision resistant, if finding a collision can be reduced to the known hard problems. Family of MD hash functions are one of the most famous applied hash functions which are considerably used in industrial applications. However, they are not...
Key Management for Large Scale Mobile Ad-hoc Networks
, M.Sc. Thesis Sharif University of Technology ; Movaghar Rahimabadi, Ali (Supervisor)
Abstract
Mobile ad hoc networks have been attracted the attention of many researchers during last years. One of the major concerns faces such networks is the security issue. The root of this concern is the fact that the intermediate nodes have the responsibility of packet transportation and forwarding. The nodes inside the mobile ad hoc networks assumed to be trusty while they can read, change or drop the transported packets. Cryptography as the cornerstone of the security could be play an essential role in such networks. Any cryptosystem need some keys to be able to secure communications. In large scale mobile ad hoc networks storing the whole keys in all nodes is inefficient, if possible, due to...
Regular Expression Based Search on Encrypted Outsourced Data
, M.Sc. Thesis Sharif University of Technology ; Jalili, Rasool (Supervisor)
Abstract
As cloud computing becomes a ubiquitous technology, data outsourcing, which means delegating storage and retrieval of the data to an extraneous service provider, becomes more popular. One of the main issues in data outsourcing is preserving data confidentiality and privacy. A common solution to this problem is encrypting the data before outsourcing, but this approach prevents the service provider from doing computations on the data. A trivial solution is to transfer all of the data to the client-side and decrypt it before doing the computations, but this solution imposes a large overhead on the client-side and contradicts the philosophy of outsourcing. Till now, so many encryption schemes...
A Primer to Bayesian Methods in Cryptanalysis
, M.Sc. Thesis Sharif University of Technology ; Daneshgar, Amir (Supervisor)
Abstract
In this thesis, based on the model introduced in [Murphy et. al., Likelihood Estimation for Block Cipher Keys, 1995], we discuss the possibility of unifying the cryptanalysis methods. First, the model for cryptanalysis is discussed and explained by modelling several known statistical attack. In the end, using this model, we propose attacks more general than linear and differential methods
Security analysis and confidentiality in the Internet of Things
, M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza (Supervisor)
Abstract
Nowadays, Internet of Things is considered as a global infrastructure to establish communication between physical world and virtual world by using existing technologies. Its purpose is enabling things to establish communication with anything and any person in any time and any place by using existing networks and services. This technology makes different aspects of people's life smarter, facilitates doing works, and increases the quality of people's life. But, the development of Internet of Things faces to fundamental challenges that one of the most important of them is security and privacy preserving of users. According to the projects of European Research Cluster on the Internet of Things...
A Confidentiality and Integrity Preserving Architecture for Secure Data Outsourcing
, M.Sc. Thesis Sharif University of Technology ; Jalili, Rasool (Supervisor)
Abstract
Infrastructural costs of data management, have led people and organizations to outsource their data. This approach is facing with some significant security challenges and risks. The goal of this research, is to present an architecture for secure outsourcing of data in a way that used methods, storage processes, query processing methods and access control mechanisms work together to preserve confidentiality and integrity of outsourced data. In this architecture, the main challenge is transparent placement of some components between client and server in order to prevent user from being aware of communication with a secured server. In order to create this degree of transparency, we need to pay...
Comparison of Switching Stream Cipher Systems
, M.Sc. Thesis Sharif University of Technology ; Daneshgar, Amir (Supervisor)
Abstract
In this thesis, we analyze and compare switching and CPSP cryptography systems. CPSP is a dynamic system which can act as synchronized or self-synchronized stream cipher under specific conditions. To do the comparison, first we have a brief review of cryptography fundamentals like stream cipher systems, synchronized stream ciphers, and self-synchronized ones. Then, we consider chaos systems in general form and then we present their role in cryptography systems, and in continue by introducing switching cryptography systems and also CPSP cryptography systems, and analyzing their relation with self-synchronized stream ciphers, we do our statistical tests on them
Secure Data Collection in Wireless Multimedia Sensor Networks
, M.Sc. Thesis Sharif University of Technology ; Hemmatyar, Mohammad Afshin (Supervisor)
Abstract
Wireless Multimedia Sensor Networks (WMSNs) have many applications in survilient systems. In this kind of applications, although we have limited energy and computational power, we should provide minimal security to transfer data in such networks. These constraints are more crucial when we use multimedia that has more data for processing and transmission. Because of this huge amount of data, we must use compression for using less energy in both processing and transmission.
In some algorithms, it has been proposed to integrate compression and encryption in order to decrease time and power consumption. The proposed algorithm is several times faster than AES (Advanced Encryption Standard) or...
In some algorithms, it has been proposed to integrate compression and encryption in order to decrease time and power consumption. The proposed algorithm is several times faster than AES (Advanced Encryption Standard) or...
Implementing a Variant of Hyperledger Fabric with Post-Quantum Digital Signature
, M.Sc. Thesis Sharif University of Technology ; Bayat Sarmadi, Siavash (Supervisor)
Abstract
Hyperledger Fabric is an open-source modular platform to launch permissioned-blockchains for use cases like banking and supply chains. This system uses the elliptic curve digital signature algorithm to authenticate transactions. The advent and progress of quantum computers have threatened the security of classical cryptographic schemes; therefore, the process of re- placing these schemes with post-quantum alternatives has gained considerable importance.This research intends to replace the elliptic curve digital signature algorithm with post-quantum digital signatures by using the algorithms passed to the third round of the National Institute of Science and Technologies (NIST) post- quantum...
An efficient and provably-secure coercion-resistant e-voting protocol
, Article 2013 11th Annual Conference on Privacy, Security and Trust, PST 2013 ; 2013 , Pages 161-168 ; 9781467358392 (ISBN) ; Dousti, M. S ; Jalili, R ; Sharif University of Technology
2013
Abstract
We present an efficient and provably-secure e-voting protocol, which is a variant of the JCJ e-votingprotocol (Juels et al., 2010). It decreases the total number of JCJ's operations from O(n2) to O(n), where n is the number of votes or voters (whichever is the maximum). Note that since the operations under consideration are time-consuming (e.g., public-key encryption), the improvement is quite substantial. As a rough comparison, consider a nation-wide election with around ten million voters/votes. Assuming each operation takes one microsecond, and no parallelization is used, one can see a huge difference: our protocol tallies the votes in 10 seconds, while the JCJ protocol requires over 3...
Quantum secret sharing and random hopping: Using single states instead of entanglement
, Article Physical Review A - Atomic, Molecular, and Optical Physics ; Volume 92, Issue 3 , September , 2015 ; 10502947 (ISSN) ; Asoudeh, M ; Sharif University of Technology
American Physical Society
2015
Abstract
Quantum secret sharing (QSS) protocols between N players, for sharing classical secrets, either use multipartite entangled states or use sequential manipulation of single d-level states only when d is prime (A. Tavakoli, arXiv:1501.05582). We propose a sequential scheme which is valid for any value of d. In contrast to A. Tavakoli et al. whose efficiency (number of valid rounds) is 1d, the efficiency of our scheme is 12 for any d. This, together with the fact that in the limit d the scheme can be implemented by continuous variable optical states, brings the scheme into the domain of present day technology
Improved linear cryptanalysis of reduced-round SIMON-32 and SIMON-48
, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 6 December 2015 through 9 December 2015 ; Volume 9462 , December , 2015 , Pages 153-179 ; 03029743 (ISSN); 9783319266169 (ISBN) ; Alizadeh, J ; Alkhzaimi, H. A ; Aref, M. R ; Bagheri, N ; Gauravaram, P ; Biryukov A ; Goyal V ; Sharif University of Technology
Springer Verlag
2015
Abstract
In this paper we analyse two variants of SIMON family of light-weight block ciphers against variants of linear cryptanalysis and present the best linear cryptanalytic results on these variants of reducedround SIMON to date. We propose a time-memory trade-off method that finds differential/ linear trails for any permutation allowing low Hamming weight differential/ linear trails. Our method combines low Hamming weight trails found by the correlation matrix representing the target permutation with heavy Hamming weight trails found using a Mixed Integer Programming model representing the target differential/linear trail. Our method enables us to find a 17-round linear approximation for SIMON-48...
Selecting a reliable steganography method
, Article MCIT'2010 : International Conference on Multimedia Computing and Information Technology, 2 March 2010 through 4 March 2010, SharjahMCIT'2010 ; 2010 , Pages 69-72 ; 9781424470037 (ISBN) ; Jamzad, M ; Sharif University of Technology
2010
Abstract
Due to the various contents of images, the stego images produced by a steganography method may have different levels of undetectability against steganalyzers. In other words, a steganography method may cause less detectable statistical artifacts on some images compared to other images. In this paper, we analyze different features of images to find the similarity between proper cover images for each steganography method Similarity between images is modeled in form of fuzzy if-then rules using an evolutionary algorithm. Subsequently for hiding secret data in a cover image, we suggest a reliable steganography method that results in an undetectable stego image against most recently reported...
On the security of YRL, an anonymous broadcast encryption scheme
, Article 8th International Symposium on Telecommunications, IST 2016, 27 September 2016 through 29 September 2016 ; 2017 , Pages 752-755 ; 9781509034345 (ISBN) ; Ameri, M. H ; Delavar, M ; Mohajeri, J ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
Broadcast encryption is a novel concept for sending a special message to a subset of users. In broadcast encryption schemes, the distribution center broadcasts the message in encrypted form and expect that only the intended users be able to decrypt the message. This concept has several applications such as pay-per-service TVs. In this paper, we investigate one of the most recent broadcast encryption schemes and show that the introduced scheme does not provide the main requirement of broadcast encryption schemes. For this purpose, we demonstrate that all of the users, including authorized and unauthorized users, can decrypt the broadcasted encrypted message. © 2016 IEEE
Dual-rail transition logic: A logic style for counteracting power analysis attacks
, Article Computers and Electrical Engineering ; Volume 35, Issue 2 , 2009 , Pages 359-369 ; 00457906 (ISSN) ; Shalmani, M. T .M ; Salmasizadeh, M ; Sharif University of Technology
2009
Abstract
In this paper, a new logic style is proposed to be used in the implementation of cryptographic algorithms. The aim of this approach is to counteract power analysis attacks. The proposed technique is based on the transition signaling. In dual-rail transition logic, one-bit value is transmitted by a transition on the proper signal of a couple of wires. According to this concept, converter units and logic gates are defined; it is proposed to use flip-flops to build DTL alternative parts. Although the usage of flip-flops leads to increase the required area, experimental results show that the power consumption of DTL circuits depends on unpredictable initial state of T-flip-flops. In other words,...
On the effect of spatial to compressed domains transformation in LSB-based image steganography
, Article 7th IEEE/ACS International Conference on Computer Systems and Applications, AICCSA-2009, Rabat, 10 May 2009 through 13 May 2009 ; 2009 , Pages 260-264 ; 9781424438068 (ISBN) ; Ghotbi, M ; Ghaemmaghami, S ; Sharif University of Technology
2009
Abstract
This paper introduces an efficient scheme to image steganography by introducing the hidden message (payload) insertion in spatial domain and transforming the stego-image to compressed domain. We apply a recently-proposed LSB method in order to obtain better statistical behavior of the stego-message and subsequently, the obtained stego-image is transformed and quantized in order to enhance the security of hiding. Performance analysis comparisons confirm a higher efficiency for our proposed method. Compared to recently-proposed approaches, our method offers the advantage that it combines an efficient LSB method with transform domain security. © 2009 IEEE
A novel secret sharing scheme from audio perspective
, Article 2008 International Symposium on Telecommunications, IST 2008, Tehran, 27 August 2008 through 28 August 2008 ; October , 2008 , Pages 13-18 ; 9781424427512 (ISBN) ; Eghlidos, T ; Aref, M. R ; Sharif University of Technology
2008
Abstract
In this paper, a new audio secret sharing scheme which is secure and ideal is proposed. This scheme is (k, n) threshold for k ≥ 2, where the previous schemes were (2, n). It is assumed that both, "shares" and "secret", are audio files instead of a bit string secret proposed in the previous works. The audio secret is reconstructed without any computation, that is only by playing audio shares simultaneously. Moreover, the simulation results shows that the new scheme is not sensitive to audio noise. ©2008 IEEE
Improved collage steganography
, Article 4th IEEE International Conference on Emerging Technologies 2008, ICET 2008, Rawalpindi, 18 October 2008 through 19 October 2008 ; February , 2008 , Pages 223-227 ; 9781424422111 (ISBN) ; Shirali Shahreza, M ; Sharif University of Technology
2008
Abstract
Establishing Hidden Communication Is An Important Subject That Nowadays Has Gained Increasing Importance. Embedding A Secret Message Into A Cover Media Without Attracting Any Attention, Known As Steganography, Is One Of The Methods Used For Hidden Communication Purposes. In This Paper, We Present An Advanced Version Of "Collage Steganography" Method Which Is Robust Against Various Attacks. In This Method, An Image (For Example A View Of A Room) Is Created Which Contains Some Coded Information. This Method Is Robust Against Attacks Such As Adding Noise, Blurring And Jpeg Compression
An improved version of persian/arabic text steganography using "La" word
, Article Proceedings of IEEE 2008 6th National Conference on Telecommunication Technologies and IEEE 2008 2nd Malaysia Conference on Photonics, NCTT-MCP 2008, 26 August 2008 through 28 August 2008, Putrajaya ; 2008 , Pages 372-376 ; 9781424422159 (ISBN) ; Shirali Shahreza, M. H ; Sharif University of Technology
2008
Abstract
By expanding communication, in some cases there is a need for hidden communication. Steganography is one of the methods used for hidden exchange of information. Steganography is a method to hide the information under a cover media such as image or text. One of the text steganography methods for Persian and Arabic texts is "La" steganography method. But that method increases the file size and changes the apparent of the text. In this paper a method for solving these problems is proposed. In Persian and Arabic, each letter can have four different shapes regarding to its position in the word. In this method by using this feature of Persian and Arabic languages and the way which documents are...