• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권11호
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• pp.4028-4049
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• 2014

Attribute-based encryption (ABE) is a promising cryptographic primitive for implementing fine-grained data sharing in cloud computing. However, before ABE can be widely deployed in practical cloud storage systems, a challenging issue with regard to attributes and user revocation has to be addressed. To our knowledge, most of the existing ABE schemes fail to support flexible and direct revocation owing to the burdensome update of attribute secret keys and all the ciphertexts. Aiming at tackling the challenge above, we formalize the notion of ciphertext-policy ABE supporting flexible and direct revocation (FDR-CP-ABE), and present a concrete construction. The proposed scheme supports direct attribute and user revocation. To achieve this goal, we introduce an auxiliary function to determine the ciphertexts involved in revocation events, and then only update these involved ciphertexts by adopting the technique of broadcast encryption. Furthermore, our construction is proven secure in the standard model. Theoretical analysis and experimental results indicate that FDR-CP-ABE outperforms the previous revocation-related methods.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권7호
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• pp.1935-1950
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• 2023

The arrival of the Internet of Things and 5G technology enables users to rely on edge computing platforms to process massive data. Data sharing based on edge computing refines the efficiency of data collection and analysis, saves the communication cost of data transmission back and forth, but also causes the privacy leakage of a lot of user data. Based on attribute-based encryption and blockchain technology, we design a fine-grained access control scheme for data in edge computing, which has the characteristics of verifiability, support for outsourcing decryption and user attribute revocation. User attributes are authorized by multi-attribute authorization, and the calculation of outsourcing decryption in attribute encryption is completed by edge server, which reduces the computing cost of end users. Meanwhile, We implemented the user's attribute revocation process through the dual encryption process of attribute authority and blockchain. Compared with other schemes, our scheme can manage users' attributes more flexibly. Blockchain technology also ensures the verifiability in the process of outsourcing decryption, which reduces the space occupied by ciphertext compared with other schemes. Meanwhile, the user attribute revocation scheme realizes the dynamic management of user attribute and protects the privacy of user attribute.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권4호
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• pp.1404-1423
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• 2015

In smart grid, electricity consumption data may be handed over to a third party for various purposes. While government regulations and industry compliance prevent utility companies from improper or illegal sharing of their customers' electricity consumption data, there are some scenarios where it can be very useful. For example, it allows the consumers' data to be shared among various energy resources so the energy resources are able to analyze the data and adjust their operation to the actual power demand. However, it is crucial to protect sensitive electricity consumption data during the sharing process. In this paper, we propose a fine-grained access control scheme (FAC) with efficient attribute revocation and policy updating in smart grid. Specifically, by introducing the concept of Third-party Auditor (TPA), the proposed FAC achieves efficient attribute revocation. Also, we design an efficient policy updating algorithm by outsourcing the computational task to a cloud server. Moreover, we give security analysis and conduct experiments to demonstrate that the FAC is both secure and efficient compared with existing ABE-based approaches.

• 정보처리학회논문지C
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• 제19C권1호
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• pp.63-70
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• 2012

원격 헬스케어(e-Healthcare) 서비스에서 취급되는 의료정보는 개인의 프라이버시를 침해할 수 있으므로 암호화 등의 보안기술 도입이 필수적이다. 민감한 의료정보를 보호하기 위해서 접근 권한을 위임받은 사용자만 데이터에 접근 가능하며 또한, 위임된 접근 권한을 철회하는 기능이 필요하다. 이러한 요구사항에 근거하여 속성기반 암호화가 제안되었다. 본 논문에서는 안전한 원격 헬스케어 서비스를 위해서 의료데이터의 접근 권한에 대한 위임 및 철회기능을 수행할 수 있는 속성기반 암호화를 원격 헬스케어 모니터링 시스템에 적용한다. 그리고 속성기반 암호화를 이용하여 원격 헬스케어 모니터링 시스템을 구성한다. 마지막으로 시스템 이용에 장애가 될 수 있는 사용자간의 공모 공격에 대해서 분석한다.

• 한국군사과학기술학회지
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• 제17권3호
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• pp.358-363
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• 2014

In this paper, we present two constructions of the attribute-based broadcast encryption(ABBE) algorithm. Attribute-based encryption(ABE) algorithm enables an access control mechanism over encrypted data by specifying access policies among private keys and ciphertexts. ABBE algorithm can be used to construct ABE algorithm with revocation mechanism. Revocation has a useful property that revocation can be done without affecting any non-revoked uers. The main difference between our algorithm and the classical ones derived from the complete subtree paradigm which is apt for military hierarchy. Our algorithm improve the efficiency from the previously best ABBE algorithm, in particular, our algorithm allows one to select or revoke users by sending ciphertext of constant size with respect to the number of attributes and by storing logarithm secret key size of the number of users. Therefore, our algorithm can be an option to applications where computation cost is a top priority and can be applied to military technologies in the near future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권5호
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• pp.1634-1652
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• 2022

Due to the increasing need for data sharing in the age of big data, how to achieve data access control and implement user permission revocation in the blockchain environment becomes an urgent problem. To solve the above problems, we propose a novel blockchain-based data sharing scheme (BDSS) with fine-grained access control and permission revocation in this paper, which regards the medical environment as the application scenario. In this scheme, we separate the public part and private part of the electronic medical record (EMR). Then, we use symmetric searchable encryption (SSE) technology to encrypt these two parts separately, and use attribute-based encryption (ABE) technology to encrypt symmetric keys which used in SSE technology separately. This guarantees better fine-grained access control and makes patients to share data at ease. In addition, we design a mechanism for EMR permission grant and revocation so that hospital can verify attribute set to determine whether to grant and revoke access permission through blockchain, so it is no longer necessary for ciphertext re-encryption and key update. Finally, security analysis, security proof and performance evaluation demonstrate that the proposed scheme is safe and effective in practical applications.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권1호
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• pp.302-322
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• 2021

In the system of ciphertext policy attribute-based encryption (CP-ABE), only when the attributes of data user meets the access structure established by the encrypter, the data user can perform decryption operation. So CP-ABE has been widely used in personal health record system (PHR). However, the problem of key abuse consists in the CP-ABE system. The semi-trusted authority or the authorized user to access the system may disclose the key because of personal interests, resulting in illegal users accessing the system. Consequently, aiming at two kinds of existing key abuse problems: (1) semi-trusted authority redistributes keys to unauthorized users, (2) authorized users disclose keys to unauthorized users, we put forward a CP-ABE scheme that has authority accountability, user traceability and supports arbitrary monotonous access structures. Specifically, we employ an auditor to make a fair ruling on the malicious behavior of users. Besides, to solve the problem of user leaving from the system, we use an indirect revocation method based on trust tree to implement user revocation. Compared with other existing schemes, we found that our solution achieved user revocation at an acceptable time cost. In addition, our scheme is proved to be fully secure in the standard model.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권1호
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• pp.145-164
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• 2023

Cloud computing offers a platform that is both adaptable and scalable, making it ideal for outsourcing data for sharing. Various organizations outsource their data on cloud storage servers for availing management and sharing services. When the organizations outsource the data, they lose direct control on the data. This raises the privacy and security concerns. Cryptographic encryption methods can secure the data from the intruders as well as cloud service providers. Data owners may also specify access control policies such that only the users, who satisfy the policies, can access the data. Attribute based access control techniques are more suitable for the cloud environment as they cover large number of users coming from various domains. Multi-authority attribute-based encryption (MA-ABE) technique is one of the propitious attribute based access control technique, which allows data owner to enforce access policies on encrypted data. The main aim of this paper is to comprehensively survey various state-of-the-art MA-ABE schemes to explore different features such as attribute and key management techniques, access policy structure and its expressiveness, revocation of access rights, policy updating techniques, privacy preservation techniques, fast decryption and computation outsourcing, proxy re-encryption etc. Moreover, the paper presents feature-wise comparison of all the pertinent schemes in the field. Finally, some research challenges and directions are summarized that need to be addressed in near future.

• 한국통신학회논문지
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• 제29권2C호
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• pp.342-347
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• 2004

공개키 기반구조에서 공개키인증서는 신분확인을 위한 인증서로서 인증기관(Certificate Authority : CA)에서 전자적으로 서명되어 진다. 또 속성인증서(Attribute Certificate : AC)는 사용자의 속성 정보를 저장 관리하는 인증서로서 속성인증기관(Attribute Certificate Authority : ACA)에 의해 전자적으로 서명된다. 웹 상의 많은 응용에서 이들이 사용되기 위해서는 속성인증서를 적절한 신분인증서에 결합하는 바인딩 메커니즘이 필요하며, 이 인증서들간에 종속성이 유지되어야 한다. 본 논문에서 잘 알려진 바인딩 메커니즘인 선택적 철회 방식과 암호적 바인딩 방식을 분석하고, 위의 방식들이 갖고 있는 문제점을 해결하기 위한 하나의 대안으로 일회성 속성인증서를 사용하는 새로운 방식을 제안한다.

• 정보학연구
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• 제5권4호
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• pp.81-88
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• 2002

신분인증서는 신분확인을 위한 인증서로서 인증기관(Certificate Authority)에서 전자적으로 서명되어 진다. 또 속성인증서는 사용자의 속성정보를 저장 관리하는 인증서로서 속성인증기관(Attribute Certificate Authority)에 의해 전자적으로 서명된다. 웹 상의 많은 응용에서 이들이 사용되기 위해서는 속성인증서를 적절한 신분인증서에 결합하는 바인딩 메카니즘이 필요하다. 이 논문에서 우리는 잘 알려진 바인딩 메카니즘인 선택적 철회 방식[5]과 암호적 바인딩 방식[3]을 분석하고, 위의 방식들이 갖고 있는 문제점을 해결하기 위한 하나의 새로운 방식을 제안한다.