ElGamal Research Articles

A Novice’s Perception of Partial Homomorphic Encryption Schemes

Objectives: Homomorphic Encryption is a way of performing computations on encrypted data. In this paper, we explore two famous Homomorphic Encryption schemes (RSA and ElGamal) with illustrations and related security issues. Methods/ Analysis: Both RSA and ElGamal encryption techniques possess multiplicative homomorphic property. These algorithms support only one operation (multiplication) on encrypted data and so they are termed as partial homomorphic encryption schemes. By using RSA and ElGamal, the encrypted data could be multiplied together without performing decryption. If needed, the results after such computations could be returned in decrypted form. This scheme reduces computation time and increases security and privacy of data being processed. Findings: It has been described how RSA and ElGamal algorithms perform key generation, encryption and decryption with simple illustrations. It has also been proved that RSA and ElGamal algorithms support multiplication operation on encrypted data with examples. Improvement/Applications: Many organizations rely on third party to outsource their large amount of electronic data for storage. It may be needed to perform some computations on the encrypted data on the server side provided by untrusted third party. Homomorphic Encryption will be much useful in such applications.

High Performance Design of Elgamal Cyrptographic Algorithm using Vedic Mathematics

Objectives: Vedic mathematics contains 16 formulae or Sutras. Employing these shortcut formulae in the computations of Elgamal cryptographic algorithm will reduce the logic elements, layout area and power consumption. Methods/Statistical Analysis: Simulation programming for the paper has been done through Verilog HDL code in MODELSIM software and performance parameters like speed, power etc., using XILINX software. Findings: In this paper, when employing these Vedic formulae, lesser number of logic elements are consumed when compared with conventional method. Improvements/ Applications: By investigating the various Sutras in Vedic mathematics, it has been observed that speed is increased and layout area is minimized.

Small-world: Secure friend matching over physical world and social networks

The explosive growths of Social Networks and smart devices over the past decade have redefined the way people interact with their friends and build social connections with physical-proximate others. Unfortunately, increasing backbone network traffic and privacy concerns of the information leakage during the friend matching process limit the expansion of users’ friend circles. To address the problem, we propose Small-World, which aims to achieve secure friend matching over physical world and social networks simultaneously. Specifically, we design a physical proximity module, which is based on a novel weight-aware spatiotemporal similarity function with considering a set of factors such as hot zones for each user, the distribution of Point of Interests and users’ whereabouts. Then we build a Katz score-based social strength proximity module, which is a bidirectional and social strength-aware similarity function, to calculate the similarity between social network users. We design an El Gamal cryptosystem-based solution, termed Protocol I, to realize secure 2-hop social strength matching and further extend it to Protocol II, which aims to establish multi-hop (4-hop at most) social connection chain between two users. Finally, we design a weight assigning function based on the linear regression to evaluate the importance of the physical proximity module and it of social strength proximity module. Thorough security analysis and performance results indicate the effectiveness and efficiency of our proposed scheme.

A Practical Privacy-Preserving Recommender System

The main goal of a personalized recommender system is to provide useful recommendations on various items to the users. In order to generate recommendations, the service needs to access various types of user data such as previous product purchasing history, demographic and biographical information. However, users are sensitive to disclosure of personal information as it can be easily misused by malicious third parties. Consequently, there are unavoidable security concerns which will become known through attempted unauthorized access while providing the recommendation services. In order to protect against breaches of personal information, it is necessary to obfuscate the user information by means of an efficient encryption technique while simultaneously generating the recommendation by making true information inaccessible to the system. To address these challenges, we propose a privacy-preserving recommender system using homomorphic encryption, by which the system can provide recommendations without knowing the actual ratings. Our approach is based on the ElGamal cryptosystem by which both addition and multiplication of plaintexts can be performed. The performance of the proposed scheme shows significantly high accuracy in-terms of computation and communication costs as well as outperforming other existing solutions.

A secure and efficient payment protocol based on ElGamal cryptographic algorithms

In this paper we present a secure and efficient transaction protocol that provides the anonymity and can detect the double spending. The proposed payment system is based on the ElGamal encryption scheme, the ElGamal signature scheme and the ElGamal blind signature protocol. We show that our transaction protocol is secure and efficient. We give the definitions of unlinkability and unforgeability of our security model and we prove that the proposed transaction protocol is unforgeable and satisfies the unlinkability property. We show that the proposed system is more efficient, in terms of the computation and communication cost, than the compared payment systems (Eslami et al. in Electron Commer Res Appl 10:59–66, 2011; Chen et al. in Electron Commer Res Appl 10:279–287, 2011; Liu et al. in Proceedings of second European PKI workshop: research and applications. Lecture notes in computer science, vol 3545, pp 206–214, 2005 and Chen et al. in Electron Commer Res Appl 10:673–682, 2011) for a customer who withdraws and spends an e-coin and for the merchant who verifies an electronic coin. Also, the proposed e-cash system is useful for the electronic transactions when the connection between the bank and the merchant is not available during the payment protocol. This means a less bandwidth of the payment protocol and then increases the speed of the electronic transaction.

Review of Privacy Preserving Public Auditing Techniques

computing provides services where can store their data remotely on cloud and can access their data from anywhere, anytime by means of internet. Cloud computing enables to use the data stored on cloud as if the data is local without worrying about its accuracy and reliability. But a major challenge in cloud computing is to ensure the integrity of users outsourced data on cloud server. Public auditing service makes use of an independent third party to check data storage correctness on cloud on behalf of data owner itself. This paper analyzes various techniques employed in order to perform secure cloud auditing to verify the integrity of outsourced data on cloud. Also it discusses limitations associated with these protocols and lastly proposes a scheme to ensure privacy and security in public auditing for cloud storage Keywordscomputing; Data Integrity; ElGamal algorithm; SHA- 256; Third party auditor.

ELGAMAL DIGITAL SIGNATURE SCHEME WITH INTEGRATED CFEA-TECHNIQUE

One of the four security goals is authentication. Authentication is a mechanism to ensure that we are communicating with the intended party. If Alice and Bob want to communicate securely, then the authentication mechanism will be able to ensure that Alice is truly communicating with Bob, and Bob is truly communicating with Alice. This mechanism can be provided by the cryptography. One of the most established cryptography schemes is ElGamal cryptosystem. The original version of this cryptosystem is to provide confidentiality through encryption and decryption procedures. By manipulating these procedures, the authentication mechanism can be carried out. Thus, ElGamal Digital Signature Scheme emerges as one of the most popular authentication mechanisms. In order to provide good level of security, proper parameters must be used in this scheme. This includes the size of the parameters. Larger parameters will provide a better level of security. As a consequence, the performance of the scheme becomes an issue in real life application. In this paper, we proposed the enhancement of the ElGamal Digital Signature Scheme by integrating the Continued-Fraction-Euclidean-Algorithm (CFEA) technique. This technique is able to reduce the number of data to be processed in the signing and verification procedures. By integrating the CFEA-technique into the ElGamal Digital Signature Scheme, any number of documents can be compressed becomes a pair of documents. Therefore, the signing and verification procedures can be done in smaller number of steps.

IMPLEMENTASI ALGORITMA ELGAMAL DALAM SISTEM LOCK BRANKAS BERBASIS MIKROKONTROLER ATMEGA16 DAN SMARTPHONE ANDROID

Most of Safes lock system is still using conventional methods nowadays. The conventional method leads to the safes’ burglary. Some of the causes are the safes’ code that can be tracked easily and the key can be duplicated. Previous research on safes’ security has ever been done. The weakness of the study is there is no security system using cryptographic algorithms for data security. The development of a safes security system by implementing ElGamal algorithms is done by following the engineering approach with the stages of methods analysis and design system, implementation and testing of the analysis and the discussion of the overall system. In the analysis and design of mathematical models using ElGamal algorithms, uses fast powering theorems and applications design uses Object OrientedProgramming. In the analysis of hardware refers to the datasheet and calculation of the value of electrical characteristics of the circuit. In the safes lock system, the outcome of the research is a safes prototype which is equipped with enhancements that include a series of processing algorithms, the data viewer, a wireless data transfer device, the Android smartphone as a system of user authorization. For the lock safes systems is using a locked solenoid. The control system is done by a lock safes android smartphone via Bluetooth communication. The test results also indicate the system will open the safes if the code and the public key is entered correctly, and the system will not open if one of the codes or the public-keys are wrong or both are wrong.

A Simple Proof for the Optimality of Randomized Posterior Matching

Posterior matching (PM) is a sequential horizon-free feedback communication scheme introduced by the authors, who also provided a rather involved optimality proof, showing that it achieves capacity for a large class of memoryless channels. Naghshvar et al. considered a non-sequential variation of PM with a fixed number of messages and a random decision-time, and gave a simpler proof establishing its optimality via a novel extrinsic Jensen–Shannon divergence argument. Another simpler optimality proof was given by Li and El Gamal, who considered a fixed-rate fixed block-length variation of PM with an additional randomization. Both these works also provided error exponent bounds. However, their simpler achievability proofs apply only to discrete memoryless channels, and are restricted to a non-sequential setup with a fixed number of messages. In this paper, we provide a short and transparent proof for the optimality of the fully sequential randomized horizon-free PM scheme over general memoryless channels. Borrowing the key randomization idea of Li and El Gamal, our proof is based on analyzing the random walk behavior of the shrinking posterior intervals induced by a reversed iterated function system decoder.

An ElGamal Encryption with Fuzzy Keyword Search on Cloud Environment

With the continuous development of cloud computing, more and more sensitive data needs to be centrally stored in the cloud storage. For protecting the privacy of data, sensitive data must be encrypted before being outsourced to the server. The traditional PEKS (Public Encryption Keyword Search) enables users to search data by using keywords in the condition of encryption, however, it not only needs the security channel but also tolerates the huge pairing-computation. Although the pairing-free public key encryption with keyword search has been proposed, it can not support fuzzy keyword search and this drawback greatly reduces the usability of the system. In this paper, the proposed scheme features three good aspects: First, the keywords and data have been encrypted under the server's public key and thus the secure channel of the keywords transmission has been eliminated in the sense that the outside attackers cannot obtain any information related to the keywords without the knowledge of the server's private key. Second, our scheme not only supports accurate keyword search encryption but also supports the search when the keywords input have any spelling mistakes or format inconsistencies, which significantly improved the availability of the system. Finally, the proposed scheme is constructed on the El Gamal encryption instead of the bilinear-pairing encryption, which greatly improve the computational efficiency.

Privacy Protection for Wireless Medical Sensor Data

In recent years, wireless sensor networks have been widely used in healthcare applications, such as hospital and home patient monitoring. Wireless medical sensor networks are more vulnerable to eavesdropping, modification, impersonation and replaying attacks than the wired networks. A lot of work has been done to secure wireless medical sensor networks. The existing solutions can protect the patient data during transmission, but cannot stop the inside attack where the administrator of the patient database reveals the sensitive patient data. In this paper, we propose a practical approach to prevent the inside attack by using multiple data servers to store patient data. The main contribution of this paper is securely distributing the patient data in multiple data servers and employing the Paillier and ElGamal cryptosystems to perform statistic analysis on the patient data without compromising the patients’ privacy.

Public Encryption Techniques for Cloud Computing: Randomness and Performance Testing

Cloud computing becomes the next-generation architecture of IT Enterprises. Cloud computing is a technology. It enables clients to use high-end services in a form of software as a service. These reside on different servers all over the world. There are many security threats in cloud computing. Data security is one of them. Data security raises client concerns. There are many issues of data security. It named maintenance of data integrity, data hiding and data safety. These threats dominate clients concerns when the issue of cloud come up. Cloud computing has a big data. Traditional encryption method is time-consuming in this environment. Cloud computing has a single security architecture. It has also many customers with different demands of security. In this case, data security is considered one of the most important issues in cloud computing. The proposed work focused on accessing data securely in cloud and desktop environment. It depends on public key cryptosystem. Generally, Data security is an important factor for both cloud computing and traditional desktop applications. Client needs to have the highest possible level of privacy. Public key cryptosystem is a good candidate for this purpose. It plays a vital role in cloud computing security and desktop. The paper presents an evaluation for selected public key cryptosystem techniques. It named ElGamal cryptosystem, modified chaotic cryptosystem and chaotic cryptosystem. A modified chaotic cryptosystem was presented. The modification enabled the same message to have different cipher version. The experiments implemented at two independent platforms namely desktop computer and Amazon EC2 Micro Instance cloud computing environment. In this paper, the selected algorithms compared according to randomness testing. A standardized NIST statistical testing is used in both desktop environment and cloud computing environment. The algorithms are implemented using python charm Cryptography framework. Simulation results are shown to demonstrate the effectiveness of each algorithm. NIST statistical tests are used to determine suitable technique for cloud computing environment and desktop. It also used to study the performance of the selected encryption techniques in both environment. General Terms Cloud computing, Security. NIST statistical testing, chaotic, a Modified chaotic, ElGamal

Medical image steganography using priority queue with Elgamal cryptosystem

This paper describes a methodology for hiding medical records and patient's identity information inside their scan medical image files using the concept of dynamic priority queue least significant bits (LSBs) substitution. Elgamal cryptosystem is used to encrypt patient's sensitive data. The outcome of the cryptosystem is organised in various priority queue blocks and sub blocks based on a secret data length of each block. The cipher text is obtained from priority queue as highest priority (weight) data will be retrieved first. Now embed the cipher text in a medical cover image at 7th bit or 8th bit position using heap-LSB technique. Authorised receiver can retrieve the correct plain text using private keys. Performance analysis is observed using various performance measure parameters between various medical stego and cover images. Results are analysed and compared with many of existing steganography algorithms.

Feeding Back the Output or Sharing the State: Which Is Better for the State-Dependent Wiretap Channel?

In this paper, the general wiretap channel with channel state information (CSI) at the transmitter and noiseless feedback is investigated, where the feedback is from the legitimate receiver to the transmitter, and the CSI is available at the transmitter in a causal or noncausal manner. The capacity-equivocation regions are determined for this model in both causal and noncausal cases, and the results are further explained via Gaussian and binary examples. For the Gaussian model, we find that in some particular cases, the noiseless feedback performs better than Chia and El Gamal’s CSI sharing scheme, i.e., the secrecy capacity of this feedback scheme is larger than that of the CSI sharing scheme. For the degraded binary model, we find that the noiseless feedback performs no better than Chia and El Gamal’s CSI sharing scheme. However, if the cross-over probability of the wiretap channel is large enough, we show that the two schemes perform the same.

A Crossbreed approach to Enhanced Security of Multimedia Data using SKIP JACK and Elgamal Algorithm

Due to the new development in computer networking expertise, delivery of the digital multimedia content through the internet is huge. However, the increase number of the digital credentials, all inclusive availability, and the multimedia dispensation tools of Internet entrance has created a very easy medium for exclusive rights trickery and out of manage distribution of multimedia contented. A most important constraint now is to protect the thinker property of multimedia content in multimedia organization. So, in this document multimedia protection will be providing using SKIP JACK and Elgamal algorithm. The full implementation is done in .NET structure.

Loss Less and Privacy Preserved Data Retrieval in Cloud Environment using TRSE

In the modern era of the computing world, the data producing and using it is becoming large and instant at various places. For availing the data at different locations for processing we need to store it in the global platform. Cloud environment provides a best and easy way for this. Cloud computing is becoming as the essential thing for high-quality data services. However there are some potential problems with respect to data security. Here encryption techniques can be used for providing security, but with restricted efficiency. In this paper we propose a new encryption mechanism for providing data security in cloud environment. We propose a two round searchable encryption which supports multi keyword retrieval. Here we adapted a vector space model for improving search accuracy; the elgamal encryption technique allows users to involve in the ranking, while the essential key part of encryption will be done at the source itself. The proposed improves the data security and reduces data leakage.

Causal Relay Networks

In this paper, we study causal discrete memoryless relay networks. The network consists of multiple nodes, each of which can be a source, a relay, and/or a destination. In the network, there are two types of relays: 1) relays with one sample delay (strictly causal) and 2) relays without delay (causal) whose transmit signals depend not only on the past received symbols but also on the current received symbols. For this network, we derive two new cut-set bounds, one when every node has a message and the other when only the strictly causal relays have messages. Using the examples of a causal vector Gaussian two-way relay channel and a causal vector Gaussian relay channel, we show that the new cut-set bounds can be achieved by a simple amplify-and-forward type relaying. Our result for the causal relay channel strengthens the previously known capacity result for the same channel by El Gamal, Hassanpour, and Mammen.

Brandt’s fully private auction protocol revisited

Auctions have a long history, having been recorded as early as 500 B.C. [17]. Nowadays, electronic auctions have been a great success and are increasingly used. Many cryptographic protocols have been proposed to address the various security requirements of these electronic transactions, in particular to ensure privacy. Brandt [4] developed a protocol that computes the winner using homomorphic operations on a distributed ElGamal encryption of the bids. He claimed that it ensures full privacy of the bidders, i.e. no information apart from the winner and the winning price is leaked. We first show that this protocol – when using malleable interactive zero-knowledge proofs – is vulnerable to attacks by dishonest bidders. Such bidders can manipulate the publicly available data in a way that allows the seller to deduce all participants’ bids. Additionally we discuss some issues with verifiability as well as attacks on non-repudiation, fairness and the privacy of individual bidders exploiting authentication problems.

Bug Attacks

In this paper we present a new kind of cryptanalytic attack which utilizes bugs in the hardware implementation of computer instructions. The best-known example of such a bug is the Intel division bug, which resulted in slightly inaccurate results for extremely rare inputs. Whereas in most applications such bugs can be viewed as a minor nuisance, we show that in the case of RSA (even when protected by OAEP), Pohlig---Hellman and ElGamal encryption such bugs can be a security disaster: decrypting ciphertexts on any computer which multiplies even one pair of numbers incorrectly can lead to full leakage of the secret key, sometimes with a single well-chosen ciphertext. As shown by recent revelation of top secret NSA documents by Edward Snowden, intentional hardware modifications is a method that was used by the USA to weaken the security of commercial equipment sent to targeted organizations.

Attribute-based versions of Schnorr and ElGamal

We design in this paper the first attribute-based cryptosystems that work in the classical discrete logarithm, pairing-free, setting. The attribute-based signature scheme can be seen as an extension of Schnorr signatures, with adaptive security relying on the discrete logarithm assumption, in the random oracle model. The attribute-based encryption schemes can be seen as extensions of ElGamal cryptosystem, with adaptive security relying on the decisional Diffie---Hellman assumption, in the standard model. The proposed schemes are secure only in a bounded model: the systems admit L secret keys, at most, for a bound L that must be fixed in the setup of the systems. The efficiency of the cryptosystems, later, depends on this bound L. Although this is an important drawback that can limit the applicability of the proposed schemes in some real-life applications, it turns out that the bounded security of our key-policy attribute-based encryption scheme (in particular, with $$L=1$$L=1) is enough to implement the generic transformation of Parno, Raykova and Vaikuntanathan at TCC'2012. As a direct result, we obtain a protocol for the verifiable delegation of computation of boolean functions, which does not employ pairings or lattices, and whose adaptive security relies on the decisional Diffie---Hellman assumption.