• Journal of Information Processing Systems
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• v.13 no.3
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• pp.573-589
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• 2017

Cloud computing is an attractive solution that can provide low cost storage and powerful processing capabilities for government agencies or enterprises of small and medium size. Yet the confidentiality of information should be considered by any organization migrating to cloud, which makes the research on relational database system based on encryption schemes to preserve the integrity and confidentiality of data in cloud be an interesting subject. So far there have been various solutions for realizing SQL queries on encrypted data in cloud without decryption in advance, where generally homomorphic encryption algorithm is applied to support queries with aggregate functions or numerical computation. But the existing homomorphic encryption algorithms cannot encrypt floating-point numbers. So in this paper, we present a mechanism to enable the trusted party to encrypt the floating-points by homomorphic encryption algorithm and partial trusty server to perform summation on their ciphertexts without revealing the data itself. In the first step, we encode floating-point numbers to hide the decimal points and the positive or negative signs. Then, the codes of floating-point numbers are encrypted by homomorphic encryption algorithm and stored as sequences in cloud. Finally, we use the data structure of DoubleListTree to implement the aggregate function of SUM and later do some extra processes to accomplish the summation.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.4
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• pp.839-845
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• 2018

Sensitive data is encrypted and stored as privacy policy is strengthened through frequent leakage of personal information. For this reason, the cryptographically owned encrypted data is a very important analysis from the viewpoint of digital forensics. Until now, the digital evidence collection procedure only considers imaging, so hardware specific information is not collected. If the encryption key is generated by information that is not left in the disk image, the encrypted data can not be decrypted. Recently, an application for performing encryption using hardware specific information has appeared. Therefore, in this paper, hardware specific information which does not remain in file form in auxiliary storage device is studied, and hardware specific information collection method is introduced.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.6
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• pp.1301-1313
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• 2012

The importance of protecting personal information is increasing day by day due to invasion of privacy, and data encryption is the most effective way to eliminate it. However, current data encryption methods tend to having problems for applying in practical fields because of critical issues such as low performances and frequent changes of applications. In order to find proper solutions for data security, this paper reviews data encryption technologies and experiments on performance of encrypted data in Oracle Database. On top of that, this paper analyses a data encryption technique not only efficiency of performance but also minimization of application changes.

• International Journal of Computer Science & Network Security
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• v.24 no.1
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• pp.140-150
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• 2024

Database-as-a-Service is one of the prime services provided by Cloud Computing. It provides data storage and management services to individuals, enterprises and organizations on pay and uses basis. In which any enterprise or organization can outsource its databases to the Cloud Service Provider (CSP) and query the data whenever and wherever required through any devices connected to the internet. The advantage of this service is that enterprises or organizations can reduce the cost of establishing and maintaining infrastructure locally. However, there exist some database security, privacychallenges and query performance issues to access data, to overcome these issues, in our recent research, developed a database security model using a deterministic encryption scheme, which improved query execution performance and database security level.As this model is implemented using a deterministic encryption scheme, it may suffer from chosen plain text attack, to overcome this issue. In this paper, we proposed a new model for cloud database security using nondeterministic encryption, order preserving encryption, homomorphic encryptionand database distribution schemes, andour proposed model supports execution of queries with equality check, range condition and aggregate operations on encrypted cloud database without decryption. This model is more secure with optimal query execution performance.

• Journal of Multimedia Information System
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• v.7 no.2
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• pp.165-174
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• 2020

This document outlines a new color image encryption technology development. After splitting the original image into 240-bit blocks and modifying the first block by an initialization vector, an improved Feistel circuit is applied, sponsored by a genetic crossover operator and then strong chaining between the encrypted block and the next clear block is attached to set up the confusion-diffusion and heighten the avalanche effect, which protects the system from any known attack. Simulations carried out on a large database of color images of different sizes and formats prove the robustness of such a system.

• Journal of KIISE
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• v.43 no.9
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• pp.1052-1059
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• 2016

A key role in cloud computing systems that is becoming an issue is implementing a database on untrusted cloud servers requiring the complexity of key management. This study proposes a key management system using Self Proxy Servers to minimize key executions and improve the performance of cloud services by generating Self-Creating Algorithms where the data owner is not directly concerned with related keys when a user sends an encrypted database a query. The Self Proxy Server supports active and autonomous key managements as a distributed server if any trouble should arise from a cloud key server and for an efficient cloud key management. Therefore, the key management system provides secure cloud services by supporting confidentiality of a cloud server database.

• Journal of Korea Multimedia Society
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• v.24 no.1
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• pp.58-66
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• 2021

The user's password must be encrypted one-way through the hash function and stored in the database. Widely used hash functions such as MD5 and SHA-1 have also been found to have vulnerabilities, and hash functions that are considered safe can also have vulnerabilities over time. Salt enhances password security by adding it before or after the password before putting it to the hash function. In the case of the existing Salt, even if it is randomly assigned to each user, once it is assigned, it is a fixed value in a specific column of the database. If the database is exposed to an attacker, it poses a great threat to password cracking. In this paper, we suggest variable-dynamic Salt that dynamically changes according to the user's password during the login process. The variable-dynamic Salt can further enhance password security during login process by making it difficult to know what the Salt is, even if the database or source code is exposed.

• Journal of Korea Multimedia Society
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• v.11 no.1
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• pp.1-12
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• 2008

Database encryption is one of the important mechanisms for prohibiting internal malicious users and outside hackers from utilizing data. Frequent occurrences of encryption and decryption cause degradation of database performance so that many factors should be considered in implementing encryption system. In this paper, we propose an architecture of database encryption system and data encryption module. In addition we suggest extended SQL in order to manage data encryption and decryption. In implementing database encryption system, we adopt ARIA encryption algorithm which is proved to be the most fast one among Korea standardized encryption algorithm. We use an single key for each database in encrypting data rather than using several keys in order to improve performance. Research over performance evaluation of database encryption system is rare up to now. Based on our implemented system, we provide performance evaluation results over various H/W platforms and compare performance differences between plain text and encrypted data.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.1
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• pp.281-298
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• 2020

Fog computing has become a popular concept in the application of internet of things (IoT). With the superiority in better service providing, the edge cloud has become an attractive solution to IoT networks. The data outsourcing scheme of IoT devices demands privacy protection as well as computation verification since the lightweight devices not only outsource their data but also their computation. Existing solutions mainly deal with the operations over encrypted data, but cannot support the computation verification in the same time. In this paper, we propose a data outsourcing scheme based on an encrypted database system with linear computation as well as efficient query ability, and enhance the interlayer program in the original system with homomorphic message authenticators so that the system could perform computational verifying. The tools we use to construct our scheme have been proven secure and valid. With our scheme, the system could check if the cloud provides the correct service as the system asks. The experiment also shows that our scheme could be as effective as the original version, and the extra load in time is neglectable.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.5
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• pp.1328-1342
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• 2013

Searchable encryption is a cryptographic protocol for searching a document in encrypted databases. A simple searchable encryption protocol, which is capable of using only one keyword at one time, is very limited and cannot satisfy demands of various applications. Thus, designing a searchable encryption with useful additional functions, for example, conjunctive keyword search, is one of the most important goals. There have been many attempts to construct a searchable encryption with conjunctive keyword search. However, most of the previously proposed protocols are based on public-key cryptosystems which require a large amount of computational cost. Moreover, the amount of computation in search procedure depends on the number of documents stored in the database. These previously proposed protocols are not suitable for extremely large data sets. In this paper, we propose a new searchable encryption protocol with a conjunctive keyword search based on a linked tree structure instead of public-key based techniques. The protocol requires a remarkably small computational cost, particularly when applied to extremely large databases. Actually, the amount of computation in search procedure depends on the number of documents matched to the query, instead of the size of the entire database.