• Journal of Communications and Networks
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• 제15권3호
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• pp.252-257
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• 2013

To alleviate the damage caused by key exposures, Dodis et al. introduced the notion of key-insulated security where secret keys are periodically updated by using a physically insulated helper key. To decrease the risk of helper key exposures, Hanaoka et al. advocated parallel key-insulated mechanism where distinct helpers are independently used in key updates. In this paper, we propose the first parallel key-insulated signature scheme which is provably secure without resorting to the random oracle methodology. Our scheme not only allows frequent key updating, but also does not increase the risk of helper key exposures.

• Journal of Ginseng Research
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• 제47권2호
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• pp.349-351
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• 2023

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권9호
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• pp.2442-2454
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• 2012

To ensure the security of wireless sensor networks, it is important to have a robust key management scheme. In this paper, we propose a Quorum-based key management scheme. A specific sensor, called as key distribution server (KDS), generates a key matrix and establishes a quorum system from the key matrix. The quorum system is a set system of subsets that the intersection of any two subsets is non-empty. In our scheme, each sensor is assigned a subset of the quorum system as its pre-distributed keys. Whenever any two sensors need a shared key, they exchange their IDs, and then each sensor by itself finds a common key from its assigned subset. A shared key is then generated by the two sensors individually based on the common key. By our scheme, no key is needed to be refreshed as a sensor leaves the network. Upon a sensor joining the network, the KDS broadcasts a message containing the joining sensor ID. After receiving the broadcast message, each sensor updates the key which is in common with the new joining one. Only XOR and hash operations are required to be executed during key update process, and each sensor needs to update one key only. Furthermore, if multiple sensors would like to have a secure group communication, the KDS broadcasts a message containing the partial information of a group key, and then each sensor in the group by itself is able to restore the group key by using the secret sharing technique without cooperating with other sensors in the group.

• 한국정보통신학회논문지
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• 제11권7호
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• pp.1332-1340
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• 2007

본 논문에서는 휴대인터넷 와이브로 (WiBro) 시스템의 보안계층 중 암호 키 (Traffic Encryption Key; TEK)를 암호 복호하는 key wrap/unwrap 알고리듬의 효율적인 하드웨어 설계에 대해 기술한다. 설계된 key wrap/unwrap 코어 (WB_KeyWuW)는 AES (Advanced Encryption Standard) 알고리듬을 기반으로 하고 있으며, 128비트의 TEK를 128비트의 KEK (Key Encryption Key)로 암호화하여 192비트의 암호화된 키를 생성하고, 192비트의 암호화된 키를 복호화하여 128비트의 TEK로 복호하는 기능을 수행한다. 효율적인 하드웨어 구현을 위해 라운드 변환 블록에 하드웨어 공유기법을 적용하여 설계하였으며, 또한 하드웨어 복잡도에 가장 큰 영향을 미치는 SubByte/InvSubByte 블록을 체 변환 방법을 적용하여 구현하였다. 이를 통해, LUT (Lookup Table)로 구현하는 방식에 비해 약 25%의 게이트 수를 감소시켰다. Verilog-HDL로 설계된 WB_KeyWuW 코어는 약 14,300개의 게이트로 구현되었으며, 100-MHz@3.3-V의 클록으로 동작하여 $16{\sim}22-Mbps$의 성능이 예상되어 와이브로 시스템 보안용 하드웨어 구현을 위한 IP로 사용될 수 있다.

• The Plant Pathology Journal
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• 제27권4호
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• pp.360-366
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• 2011

Bacterial leaf spot of Euphorbia pulcherrima has been reported in many countries. Characterization by polyphasic approaches indicated that the isolates from India, USA and New Zealand could be distinguished based on rep-PCR profiles and gyrB phylogenies, while the Chinese isolates should be ascribed to Xanthomonas axonopodis pv. poinsettiicola.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권5호
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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.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권8호
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• pp.2042-2060
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• 2013

In wireless sensor networks (WSNs), energy efficiency is one of the most essential design considerations, since sensor nodes are resource constrained. Group communication can reduce WSNs communication overhead by sending a message to multiple nodes in one packet. In this paper, in order to simultaneously resolve the transmission security and scalability in WSNs group communications, we propose a hierarchical cluster-based secure and scalable group key management scheme, called HRKT, based on logic key tree and route key tree structure. The HRKT scheme divides the group key into cluster head key and cluster key. The cluster head generates a route key tree according to the route topology of the cluster. This hierarchical key structure facilitates local secure communications taking advantage of the fact that the nodes at a contiguous place usually communicate with each other more frequently. In HRKT scheme, the key updates are confined in a cluster, so the cost of the key updates is reduced efficiently, especially in the case of massive membership changes. The security analysis shows that the HRKT scheme meets the requirements of group communication. In addition, performance simulation results also demonstrate its efficiency in terms of low storage and flexibility when membership changes massively.

• 한국컴퓨터정보학회논문지
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• 제13권7호
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• pp.173-180
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• 2008

본 논문에서는 공개키 공격에 안전한 비대칭 워터마킹 시스템을 구성하기 위하여 효과적인 공개 키 및 개인 키 생성 알고리즘을 제안한다. 공개 키와 개인 키의 생성은 특수행렬을 이용한 선형변환 방식에 기초하였으며 높은 상관도 검출이 가능하도록 구성되었다 또 공개 키 공격에 대한검증과 검출을 위한 공개 키를 추가로 생성하여 분배하는 방안을 제안하여 특정된 환경에서 공개 키 공격에 효과적으로 대응하도록 하였다. 실험결과 워터마크가 삼입된 영상에서 공개 키 및 개인 키를 이용하여 효과적으로 높은 상관도 검출을 할 수 있었으며 공개 키 공격을 받은 영상에서 추가로 발급된 검증용 공개 키를 이용하여 효과적으로 상관도 검출을 할 수 있음을 확인하였다.

• Journal of Communications and Networks
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• 제14권1호
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• pp.104-110
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• 2012

Group key agreement protocols allow a group of users, communicating over a public network, to establish a shared secret key to achieve a cryptographic goal. Protocols based on certificateless public key cryptography (CL-PKC) are preferred since CL-PKC does not need certificates to guarantee the authenticity of public keys and does not suffer from key escrow of identity-based cryptography. Most previous certificateless group key agreement protocols deploy signature schemes to achieve authentication and do not have constant rounds. No security model has been presented for group key agreement protocols based on CL-PKC. This paper presents a security model for a certificateless group key agreement protocol and proposes a constant-round group key agreement protocol based on CL-PKC. The proposed protocol does not involve any signature scheme, which increases the efficiency of the protocol. It is formally proven that the proposed protocol provides strong AKE-security and tolerates up to $n$-2 malicious insiders for weak MA-security. The protocol also resists key control attack under a weak corruption model.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권9호
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• pp.3322-3347
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• 2021

Cloud Storage is the primary component of many businesses on cloud. Majority of the enterprises today are adopting a multicloud strategy to keep away from vendor lock-in and to optimize cost. Auditing schemes are used to ascertain the integrity of cloud data. Of these schemes, only the Provable Data Possession schemes (PDP) are resilient to key-exposure. These PDP schemes are devised using Public Key Infrastructure (PKI-) based cryptography, Identity-based cryptography, etc. PKI-based systems suffer from certificate-related communication/computational complexities. The Identity-based schemes deal with the exposure of only the auditing secret key (audit key). But with the exposure of both the audit key and the secret key used to update the audit key, the auditing process itself becomes a complete failure. So, an Identity-based PDP scheme with Parallel Key-Insulation is proposed for multiple cloud storage. It reduces the risk of exposure of both the audit key and the secret key used to update the audit key. It preserves the data privacy from the Third Party Auditor, secure against malicious Cloud Service Providers and facilitates batch auditing. The resilience to key-exposure is proved using the CDH assumption. Compared to the existing Identity-based multicloud schemes, it is efficient in integrity verification.