• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.11
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• pp.967-969
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• 2013

In this paper, we propose an efficient mult-signature scheme based on a bilinear mapping for shared data in the cloud and prove the security of the proposed scheme using the difficulty of the computational Diffie-Hellman problem. For verification, the scheme is using the sum of the hash values of stored data rather than the entire data, which makes it feasible to reduce the size of the downloaded data.

• Convergence Security Journal
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• v.15 no.5
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• pp.3-8
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• 2015

Most mobile cloud computing system use public key cryptography to provide data security and mutual authentication. A variant of traditional public key technologies called Identity-Based Cryptography(IBC) has recently received considerable attention. The certificate-free approach of IBC may well match the dynamic qualities of cloud environment. But, there is a need for a lightweight secure framework that provides security with minimum processing overhead on mobile devices. In this paper, we propose to use hierarchical ID-Based Encryption in mobile cloud computing. It is suitable for a mobile network since it can reduce the workload of root Public Key Generators by delegating the privilege of user authentication and private key generation. The Identity-Based Encryption and Identity-Based Signature are also proposed and an ID-Based Authentication scheme is presented to secure data processing. The proposed scheme is designed by one-way hash functions and XOR operations, thus has low computation costs for mobile users.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.3
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• pp.181-196
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• 2014

Cloud computer technology currently provides diverse services based on a comprehensive environment ranging from hardware to solution, network and service. While the target of services has been extended from institutions and corporations to personal infrastructure and issues were made about security problems involved with protection of private information, measures on additional security demands for such service characteristics are insufficient. This paper proposes a multi-session authentication technique based on the characteristics of SaaS (Software as a Service) among cloud services. With no reliable authentication authority, the proposed technique reinforced communication sessions by performing key agreement protocol safe against key exposure and multi-channel session authentication, providing high efficiency of performance through key renewal using optimzied key table. Each formed sessions have resistance against deprivation of individual confirmation and service authority. Suggested confirmation technique that uses these features is expected to provide safe computing service in clouding environment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.1
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• pp.75-82
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• 2015

Recently, many public auditing schemes have been proposed to support public auditability that enables a third party auditor to verify the integrity of data stored in the remote cloud server. To improve the performance of the auditor, several public auditing schemes support batch auditing which allows the auditor to handle simultaneously multiple auditing delegations from different users. However, when even one data is corrupted, the batch auditing will fail and individual and repeated auditing processes will be required. It is difficult to identify the corrupted data from the proof in which distinct data blocks and authenticators of distinct users are intricately aggregated. In this paper, we extend a public auditing scheme of Wang et al. to support batch auditing for multi-cloud and multi-user. We propose an identification scheme of the corrupted cloud when the data of a single cloud is corrupted in the batch auditing of multi-cloud and multi-user.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.9
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• pp.4197-4219
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• 2017

Cloud computing is a new service to provide dynamic, scalable virtual resource services via the Internet. Cloud market is available to multiple cloud computing resource providers and users communicate with each other and participate in market transactions. However, since cloud computing is facing with more and more security issues, how to complete the allocation process effectively and securely become a problem urgently to be solved. In this paper, we firstly analyze the cloud resource allocation problem and propose a mathematic model based on combinatorial double auction. Secondly, we introduce a trust evaluation mechanism into our model and combine genetic algorithm with simulated annealing algorithm to increase the efficiency and security of cloud service. Finally, by doing the overall simulation, we prove that our model is highly effective in the allocation of cloud resources.

• Journal of the Korea Society of Computer and Information
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• v.27 no.4
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• pp.53-60
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• 2022

Recently, as the amount of data collected by drones has rapidly increased, it is necessary to support cloud computing technology that can securely and efficiently store and process data. However, various security threats such as stealing, leaking, or tampering with data communicated by drones can occur due to attackers. Therefore, there is a need for security technology to provide secure communication of data collected from drones. Among various security technologies, the KP-ABE scheme, which is attribute-based encryption, is a security technology that satisfies two characteristics: data encryption and user access control. This paper researched the KP-ABE scheme and proposed a secure data access control scheme to the drone environment. This proposed scheme provides confidentiality and integrity of data communicated in a drone environment and secure access control and availability. In addition, it provides a fast ciphertext search and constant size ciphertext among the requirements to be provided in the KP-ABE scheme.

• Convergence Security Journal
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• v.19 no.3
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• pp.61-70
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• 2019

Recently, developments on quantum computers and cloud computing have been actively conducted. Quantum computers have been known to show tremendous computing power and Cloud computing has high accessibility for information and low cost. For quantum computers, quantum error correcting codes are essential. Similarly, cloud computing requires homomorphic encryption to ensure security. These two techniques, which are used for different purposes, are based on similar assumptions. Then, there have been studies to construct quantum homomorphic encryption based on quantum error correction code. Therefore, in this paper, we propose a scheme which can process the homomorphic encryption like quantum computation by modifying the QECCs. Conventional quantum homomorphic encryption schemes based on quantum error correcting codes does not have error correction capability. However, using the proposed scheme, it is possible to process the homomorphic encryption like quantum computation and correct the errors during computation and storage of quantum information unlike the homogeneous encryption scheme with quantum error correction code.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2394-2406
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• 2016

ABE has become an effective tool for data protection in cloud computing. However, since users possessing the same attributes share the same private keys, there exist some malicious users exposing their private keys deliberately for illegal data sharing without being detected, which will threaten the security of the cloud system. Such issues remain in many current ABE schemes since the private keys are rarely associated with any user specific identifiers. In order to achieve user accountability as well as provide key exposure protection, in this paper, we propose a key-insulated ciphertext policy attribute based encryption with key exposure accountability (KI-CPABE-KEA). In our scheme, data receiver can decrypt the ciphertext if the attributes he owns match with the self-centric policy which is set by the data owner. Besides, a unique identifier is embedded into each user's private key. If a malicious user exposes his private key for illegal data sharing, his identity can be exactly pinpointed by system manager. The key-insulation mechanism guarantees forward and backward security when key exposure happens as well as provides efficient key updating for users in the cloud system. The higher efficiency with proved security make our KI-CPABE-KEA more appropriate for secure data sharing in cloud computing.

• International Journal of Computer Science & Network Security
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• v.22 no.6
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• pp.212-222
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• 2022

There has been a rapid increase in the use of cloud email services. As a result, email encryption has become more commonplace as concerns about cloud privacy and security grow. Nevertheless, this increase in usage is creating the challenge of how to effectively be searching and filtering the encrypted emails. They are popular technologies of solving the issue of the encrypted emails searching through searchable public key encryption. However, the problem of encrypted email filtering remains to be solved. As a new approach to finding and filtering encrypted emails in the cloud, we propose a ciphertext-based encrypted policy attribute-based encryption scheme and keyword search procedure based on hidden policy ciphertext. This feature allows the user of searching using some encrypted emails keywords in the cloud as well as allowing the emails filter-based server toward filter the content of the encrypted emails, similar to the traditional email keyword filtering service. By utilizing composite order bilinear groups, a hidden policy system has been successfully demonstrated to be secure by our dual system encryption process. Proposed system can be used with other scenarios such as searching and filtering files as an applicable method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.7
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• pp.3699-3719
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• 2017

Conjunctive keyword search encryption is an important technique for protecting sensitive personal health records that are outsourced to cloud servers. It has been extensively employed for cloud storage, which is a convenient storage option that saves bandwidth and economizes computing resources. However, the process of searching outsourced data may facilitate the leakage of sensitive personal information. Thus, an efficient data search approach with high security is critical. The multi-user search function is critical for personal health records (PHRs). To solve these problems, this paper proposes a novel multi-user conjunctive keyword search scheme (mNCKS) without a secure channel against keyword guessing attacks for personal health records, which is referred to as a secure channel-free mNCKS (SCF-mNCKS). The security of this scheme is demonstrated using the Decisional Bilinear Diffie-Hellman (DBDH) and Decision Linear (D-Linear) assumptions in the standard model. Comparisons are performed to demonstrate the security advantages of the SCF-mNCKS scheme and show that it has more functions than other schemes in the case of analogous efficiency.