جستجوی مقالات مرتبط با کلیدواژه "blockchain" در نشریات گروه "فناوری اطلاعات"

Today, social networks have brought a lot of convenience to their users, but there are still problems of not respecting privacy. This has caused the security and privacy protection of social network users to be important. Users share a large amount of personal data on social networks, attackers can obtain sensitive personal information simply by using social networks. and carry out various types of attacks and identity theft. Many social networks do not have their own data centers and usually store user data in third-party data centers. These centers can share this data with others and provide user data to other organizations without their knowledge. Owners of social networks can provide users' data to information agencies or use them for advertising purposes. In this research, in the first part, we have described the introduction of the subject, and then in the second part, we have discussed the literature on the subject, which is mostly focused on the centralized methods of privacy protection, and then in the third part, we have described the research method. And we have presented a method that increases the privacy of users in social networks to a great extent by using blockchain. In the fourth part, we have described the implementation of the research and finally we have concluded and summarized this research.

Data outsourcing to reliable centers for data maintenance, protection and accessibility is simple and low-cost and does not require physical infrastructure, hardware, software and human resources. However, real-world events and recent researches have shown that even reliable centers can abuse users' trust. For example, 1) make changes in the data they have, 2) delete them, or 3) make them temporarily/permanently unavailable. Data audit methods assure the data owners that the data recorded in the database is the same as the data sent by the user and reveals the changes made in it. But they only solve the first problem. In 2008, the introduction of a technology called blockchain, which had several attractive features such as transparency, immutability, and autonomy, caused the problems of many systems that needed the mentioned features to be solved. In this article, after reviewing and addressing several blockchain-based data auditing architectures and protocols, we review and analyze their general framework. Finally, we compare the reviewed works and specify some future horizons of this field.

Intrusion detection systems seek to realize several objectives, such as increasing the true detection rate, reducing the detection time, reducing the computational load, and preserving the resulting logs in such a way that they cannot be manipulated or deleted by unauthorized people. Therefore, this study seeks to solve the challenges by benefiting from the advantages of blockchain technology, its durability, and relying on IDS architecture based on multi-node cooperation. The proposed model is an intrusion detection engine based on the decision tree algorithm implemented in the nodes of the architecture. The architecture consists of several connected nodes on the blockchain platform. The resulting model and logs are stored on the blockchain platform and cannot be manipulated. In addition to the benefits of using blockchain, reduced occupied memory, the speed, and time of transactions are also improved by blockchain. In this research, several evaluation models have been designed for single-node and multi-node architectures on the blockchain platform. Finally, proof of architecture, possible threats to architecture, and defensive ways are explained. The most important advantages of the proposed scheme are the elimination of the single point of failure, maintaining trust between nodes, and ensuring the integrity of the model, and discovered logs.

Due to the fact that in recent years, the discussion of removing the national entrance exam has been raised, this year, the 12th grade average has been set for high-demand fields, which has a direct impact of 40%, and for other fields of study, admission is based on the student's academic record. Therefore, safe storage of academic records and prevention of changing and manipulating students' grades is very important. Blockchain technology is of interest due to its unique features such as decentralization and completeness of data, on the other hand, smart contracts provide privacy and access control. A platform for implementing smart contracts is the Hyperledger Fabric blockchain network. In this article, a model for storing and retrieving students' academic records based on the Hyperledger Fabric blockchain is presented. In this model, the academic records of students, including the grades of specialized and general courses of the twelfth year, are stored in the form of a transaction. The evaluation organization, as the responsible organization, can retrieve these records and provide the candidate with the result of the evaluation (being accepted or not accepted in the field of the candidate's chosen location). This model considers comprehensiveness, decentralization, privacy and access control.

Financial transactions in Bitcoin are stored in a distributed database called the block chain. All transactions are publicly available for all network nodes with the aim of transparency and the possibility of verifying the correctness. But this blockchain transparency feature, exploited by transaction analysis techniques, can lead to the violation of users’ privacy and the disclosure of their identities. Researchers have proposed various techniques such as transaction mixing or fair exchange with the aim of improving privacy in Bitcoin transactions. In this paper, we present a new mixing scheme that overcomes some of the weaknesses of previous schemes. Obviously, in the proposed scheme, users can mix different amounts of Bitcoin in each round of the protocol implementation, which leads to achieving the result in a shorter time and at a lower cost. Also, this scheme is more resistant to denial of service attacks by malicious users.

Blockchain is a revolution in the field of information and communication technology, which was able to create outstanding developments in technology and the daily life of users and affect the internet payment process, by its benefits and applications. Investing in digital currencies has always been associated with a lot of risk due to the fact that their use is separate from the real world. Recently, this risk was largely covered by smart contracts. But the reality is that a smart contract without the use of strong information management systems like Oracle is often worthless. For the global adoption of blockchains, a reliable mechanism that facilitates communication between smart contracts and the outside world is critical. Without blockchain-based oracles, smart contracts are forced to rely solely on in-network information, which significantly limits their capabilities. Decentralized oracles have the potential to create security mechanisms that remove many systemic risks from the blockchain ecosystem. Blockchain oracles are one of the most important elements that make up the blocks, which operate with a safe, reliable function and without the need for mutual trust, to improve the blockchain ecosystem. In this article, we examined the application of Oracle architecture in the management of data structures in the field of blockchain.

The development and use of electronic health records (EHR) have had remarkable impacts on human life, such as improvements in the quality of medical care, better research results, and enhancements in treatment methods. Despite these improvements, availability, security and privacy concerns have remained to be very important in this field. In this article, we propose a decentralized and distributed system for electronic health records management with the help of the blockchain technology and its potential benefits. In this system, patient information is stored in the cloud. Also, the real owner of the electronic records is the patient, and with the help of smart contracts and encryption, he/she controls how to access his/her health information. In the proposed solution, the problem of sharing and storing the patients’ keys has been solved with the help of smart contracts. In addition, we proposed solutions to special cases which are raised by transferring the control of the records to the patients such as permissions for underage patients, in emergency situations, and after the death of the patient. Comparison of the related works shows that the proposed system has solved the problems of competing systems while maintaining a high level of privacy.