• Title, Summary, Keyword: Indistinguishability

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Pseudorandom Permutation and Function Families Secure against Related-Key Attacks (연관키 공격에 안전한 의사난수 치환 및 함수 패밀리)

  • Kim, Jong-Sung;Sung, Jae-Chul;Eun, Hi-Chun
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.17 no.5
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    • pp.3-14
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    • 2007
  • In this paper, we observe that secure tweakable permutation families in the sense of strong pseudorandom permutation (SPRP) can be transformed to secure permutation families in the sense of SPRP against related-key attacks (SPRP-RKA). This fact allows us to construct a secure SPRP-RKA which is the most efficient to date. We also observe that secure function families of a certain form in the sense of a pseudorandom function (PRF) can be transformed to secure permutation families in the sense of PRP-RKA. We can exploit it to get various secure constructions against related-key attacks from known MAC algorithms. Furthermore, we define other security notions for related-key attacks, namely indistinguishability and non-malleability, and look into the relations between the security notions fur related-key attacks. We show that secure tweakable permutation families in the sense of indistinguishability (resp. non-malleability) can be transformed to secure permutation families in the sense of indistinguishability (resp. non-malleability) against related-key attacks.

A Tag Response Loss Detection Scheme for RFID Group Proof (RFID 그룹증명을 위한 응답손실 감지기법)

  • Ham, Hyoungmin
    • The Journal of the Korea Contents Association
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    • v.19 no.9
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    • pp.637-645
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    • 2019
  • The RFID group proof is an extension of the yoking proof proving that multiple tags are scanned by a reader simultaneously. Existing group proof schemes provide only delayed tag loss detection which detects loss of tag response in a verification phase. However, delayed tag loss detection is not suitable for real-time applications where tag loss must be detected immediately. In this study, I propose a tag response loss detection scheme which detects loss of tag response in the proof generation process quickly. In the proposed scheme, the tag responds with the sequence number assigned to the tag group, and the reader detects the loss of the tag response through the sequence number. Through an experiment for indistinguishability, I show that the sequence number is secure against an analyzing message attack to distinguish between specific tags and tag groups. In terms of efficiency, the proposed scheme requires fewer transmissions and database operations than existing techniques to determine which tags response is lost.

An Identity-Based Key-Insulated Encryption with Message Linkages for Peer-to-Peer Communication Network

  • Hsu, Chien-Lung;Lin, Han-Yu
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.7 no.11
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    • pp.2928-2940
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    • 2013
  • Key exposure is a major threat to secure cryptosystems. To mitigate the impact caused by key-compromise attacks, a key-insulated cryptographic mechanism is a better alternative. For securing the large message communication in peer-to-peer networks, in this paper, we propose the first novel identity-based key-insulated encryption (IB-KIE) scheme with message linkages. Our scheme has the properties of unbounded time periods and random-access key-updates. In the proposed scheme, each client can periodically update his private key while the corresponding public one remains unchanged. The essential security assumption of our proposed scheme is based on the well-known bilinear Diffie-Hellman problem (BDHP). To ensure the practical feasibility, we also formally prove that the proposed scheme achieves the security requirement of confidentiality against indistinguishability under adaptive chosen-ciphertext attacks (IND-CCA2) in the random oracle model.

Message Expansion of Homomorphic Encryption Using Product Pairing

  • Eom, Soo Kyung;Lee, Hyang-Sook;Lim, Seongan
    • ETRI Journal
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    • v.38 no.1
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    • pp.123-132
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    • 2016
  • The Boneh, Goh, and Nissim (BGN) cryptosytem is the first homomorphic encryption scheme that allows additions and multiplications of plaintexts on encrypted data. BGN-type cryptosystems permit very small plaintext sizes. The best-known approach for the expansion of a message size by t times is one that requires t implementations of an initial scheme; however, such an approach becomes impractical when t is large. In this paper, we present a method of message expansion of BGN-type homomorphic encryption using composite product pairing, which is practical for relatively large t. In addition, we prove that the indistinguishability under chosen plaintext attack security of our construction relies on the decisional Diffie-Hellman assumption for all subgroups of prime order of the underlying composite pairing group.

ZFC and Non-Denumerability (ZFC와 열거불가능성)

  • An, Yohan
    • Korean Journal of Logic
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    • v.22 no.1
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    • pp.43-86
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    • 2019
  • If 1st order ZFC is consistent(has a model($M_1$)) it has a transitive denumerable model($M_2$). This leads to a paradoxical situation called 'Skolem paradox'. This can be easily resolved by Skolem's typical resolution. but In the process, we must accept the model theoretic relativity for the concept of set. This relativity can generate a situation where the meaning of the set concept, for example, is given differently depending on the two models. The problem is next. because the sentence '¬denu(PN)' which indicate that PN is not denumerable is equally true in two models, A indistinguishability problem that the concept <¬denu> is not formally indistinguishable in ZFC arise. First, I will give a detail analysis of what the nature of this problem is. And I will provide three ways of responding to this problem from the standpoint of supporting ZFC. First, I will argue that <¬denu> concept, which can be relative to the different models, can be 'almost' distinguished in ZFC by using the formalization of model theory in ZFC. Second, I will show that <¬denu> can change its meaning intrinsically or naturally, by its contextual dependency from the semantic considerations about quantifier that plays a key role in the relativity of <¬denu>. Thus, I will show the model-relative meaning change of <¬denu> concept is a natural phenomenon external to the language, not a matter of responsible for ZFC.

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Analysis of Certificateless Signcryption Schemes and Construction of a Secure and Efficient Pairing-free one based on ECC

  • Cao, Liling;Ge, Wancheng
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.12 no.9
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    • pp.4527-4547
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    • 2018
  • Signcryption is a cryptographic primitive that provides authentication (signing) and confidentiality (encrypting) simultaneously at a lower computational cost and communication overhead. With the proposition of certificateless public key cryptography (CLPKC), certificateless signcryption (CLSC) scheme has gradually become a research hotspot and attracted extensive attentions. However, many of previous CLSC schemes are constructed based on time-consuming pairing operation, which is impractical for mobile devices with limited computation ability and battery capacity. Although researchers have proposed pairing-free CLSC schemes to solve the issue of efficiency, many of them are in fact still insecure. Therefore, the challenging problem is to keep the balance between efficiency and security in CLSC schemes. In this paper, several existing CLSC schemes are cryptanalyzed and a new CLSC scheme without pairing based on elliptic curve cryptosystem (ECC) is presented. The proposed CLSC scheme is provably secure against indistinguishability under adaptive chosen-ciphertext attack (IND-CCA2) and existential unforgeability under adaptive chosen-message attack (EUF-CMA) resting on Gap Diffie-Hellman (GDH) assumption and discrete logarithm problem in the random oracle model. Furthermore, the proposed scheme resists the ephemeral secret leakage (ESL) attack, public key replacement (PKR) attack, malicious but passive KGC (MPK) attack, and presents efficient computational overhead compared with the existing related CLSC schemes.

A Scheme of Computational Time Reduction on Back-End Server Using Computational Grid (계산 그리드를 이용한 백엔드 서버의 계산시간 단축 방안)

  • Hong, Seong-Pyo;Han, Seung-Jo
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.12
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    • pp.2695-2701
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    • 2012
  • We need privacy protection protocols, that satisfy three essential security requirements; confidentiality, indistinguishability and forward security, in order to protect user's privacy in RFID system. The hash-chain based protocol that Ohkubo et. al proposed is the most secure protocol, that satisfies all of the essential security requirements, among existing protocols. But, this protocol has a disadvantage that it takes very long time to identify a tag in the back-end server. In this paper, we propose a scheme to keep security just as it is and to reduce computation time for identifying a tag in back-end server. The proposed scheme shows the results that the identification time in back-end server is reduced considerably compared to the hash-chain based protocol.

A Study on the Tactical Aspect of Mathematical Internal Connections (수학 내적 연결성에 관한 형식적 측면 연구)

  • Yang, Seong-Hyun;Lee, Hwan-Chul
    • Journal of the Korean School Mathematics Society
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    • v.15 no.3
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    • pp.395-410
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    • 2012
  • When planning lessons and developing materials about mathematical teaching and learning, we should condignly change and reconstruct contents and orders in light of ranks and connections between subject materials. Moreover teachers should teach mathematical concepts so that students might understand then not only independently and disjunctively but also relationally and reflectively. For this, teachers have to prepare thoroughly. By analyzing advanced research for mathematical connections, this study categorizes them according to two conditions: internal-external and content-formality. Through this, tactical aspect similarity and indistinguishability between mathematical external connections and mathematical internal connections have been identified. Based upon this fact, this study proposed the principles and the examples of tactical aspect on mathematical Internal Connetions.

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Trapdoor Digital Shredder: A New Technique for Improved Data Security without Cryptographic Encryption

  • Youn, Taek-Young;Jho, Nam-Su
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.3
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    • pp.1249-1262
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    • 2020
  • Along with the increase of the importance of information used in practice, adversaries tried to take valuable information in diverse ways. The simple and fundamental solution is to encrypt the whole data. Since the cost of encryption is increasing along with the size of data, the cost for securing the data is a burden to a system where the size of the data is not small. For the reason, in some applications where huge data are used for service, service providers do not use any encryption scheme for higher security, which could be a source of trouble. In this work, we introduce a new type of data securing technique named Trapdoor Digital Shredder(TDS) which disintegrates a data to multiple pieces to make it hard to re-construct the original data except the owner of the file who holds some secret keys. The main contribution of the technique is to increase the difficulty in obtaining private information even if an adversary obtains some shredded pieces. To prove the security of our scheme, we first introduce a new security model so called IND-CDA to examine the indistinguishability of shredded pieces. Then, we show that our scheme is secure under IND-CDA model, which implies that an adversary cannot distinguish a subset of shreds of a file from a set of random shreds.

Improving Scalability using Parallelism in RFID Privacy Protection (RFID 프라이버시 보호에서 병행성을 이용한 확장성 개선)

  • Shin Myeong-Sook;Lee Joon
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.10 no.8
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    • pp.1428-1434
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    • 2006
  • In this paper, we propose the scheme solving privacy infringement in RFID systems with improving the scalability of back-end server. With RFID/USN becoming important subject, many approaches have been proposed and applied. However, limits of RFID, low computation power and storage, make the protection of privacy difficult. The Hash Chain scheme has been known as one guaranteeing forward security, confidentiality and indistinguishability. In spite of that, it is a problem that requires much of computation to identify tags in Back-End server. In this paper, we introduce an efficient key search method, the Hellman Method, to reduce computing complexity in Back-End server. Hellman Method algorism progresses pre-computation and (re)search. In this paper, after applying Hellman Method to Hash chain theory, We compared Preservation and key reference to analyze and apply to parallel With guaranteeing requistes of security for existing privacy protecting Comparing key reference reduced computation time of server to reduce computation complex from O(m) to $O(\frac{m{^2/3}}{w})$ than the existing form.