• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.6
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• pp.123-134
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• 2006

We propose a quantum secret sharing protocol which can authenticate more than half of members using GHZ state swapping. The Trusted Third Party, Trent can authenticate all members using previously shared ID among Trent distributing his message and the members wanting to reconstruct the message. Authenticated members can reconstruct a secret message through GHZ swapping. Moreover, this protocol is efficient to expand the number of members to arbitrary number n, so it is a close quantum secret sharing protocol to classical secret sharing protocol.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.4
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• pp.213-219
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• 2002

A secret sharing scheme is a kind of cryptographic protocol to maintain secret information by splitting it to many small pieces of shares and sharing between shareholders. In case of shareholders having different authorization to reconstruct the original secret, it is required a new secret sharing scheme to reflect any hierarchical structure between shareholders. In this paper, we propose a new weighted secret sharing scheme, that is, each shareholder has a weight according to the authorization of reconstructing the secret and an access set which is a subset of shareholders can reconstruct the secret if the sum of weights is equal or greater than a predefined threshold.

• The Transactions of the Korea Information Processing Society
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• v.13 no.2
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• pp.34-40
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• 2024

Secret sharing is a cryptographic technique that involves dividing a secret or a piece of sensitive information into multiple shares or parts, which can significantly increase the confidentiality of a secret. There has been a lot of research on secret sharing for different contexts or situations. Tassa's conjunctive secret sharing method employs polynomial derivatives to facilitate hierarchical secret sharing. However, the use of derivatives introduces several limitations in hierarchical secret sharing. Firstly, only a single group of participants can be created at each level due to the shares being generated from a sole derivative. Secondly, the method can only reconstruct a secret through conjunction, thereby restricting the specification of arbitrary secret reconstruction conditions. Thirdly, Birkhoff interpolation is required, adding complexity compared to the more accessible Lagrange interpolation used in polynomial-based secret sharing. This paper introduces the multi-compartment secret sharing method as a generalization of the conjunctive hierarchical secret sharing. Our proposed method first encrypts a secret using external groups' shares and then generates internal shares for each group by embedding the encrypted secret value in a polynomial. While the polynomial can be reconstructed with the internal shares, the polynomial just provides the encrypted secret, requiring external shares for decryption. This approach enables the creation of multiple participant groups at a single level. It supports the implementation of arbitrary secret reconstruction conditions, as well as conjunction. Furthermore, the use of polynomials allows the application of Lagrange interpolation.

• Review of KIISC
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• v.19 no.4
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• pp.78-84
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• 2009

최근 인터넷의 급속한 보급으로 인해 많은 정보가 네트워크를 통해서 전송되고 있는 가운데 보안상의 위험을 고려하여 비밀정보를 암호화하여 전송한다. 본 논문에서는 비밀정보를 안전하게 보내기 위해 ID기반 암호방식을 이용하여 암호화된 데이터의 공유와 권한관리에 대하여 검토하고자 한다.

• Journal of Korea Multimedia Society
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• v.16 no.5
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• pp.577-590
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• 2013

Shamir's (k,n)-threshold secret sharing scheme is not secure against cheating by attacker because the signature of participants is omitted. To prevent cheating, many schemes have been proposed, and a proactive secret sharing is one of those. The proactive secret sharing is a method to update shares in the secret sharing scheme at irregular intervals. In this paper, a proactive image secret sharing scheme over $GF(2^8)$ is proposed for the first time. For the past 30 years, Galois field operation is widely used in order to perform the efficient and secure bit operation in cryptography, and the proposed scheme with update phase of shadow image over $GF(2^8)$) at irregular intervals provides the lossless and non-compromising of secret image. To evaluate security and efficiency of images (i.e. cover and shadow images) distortion between the proposed scheme and the previous schemes, embedding capacity and PSNR are compared in experiments. The experimental results show that the performances of the embedding capacity and image distortion ratio of the proposed scheme are superior to the previous schemes.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.5_6
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• pp.239-249
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• 2003

The secret sharing is the basic concept of the threshold cryptosystem and has an important position in the modern cryptography. At 1995, Jarecki proposed the proactive secret sharing to be a solution of existing the mobile adversary and also proposed the share renewal scheme for (k, n) threshold scheme. For n participants in the protocol, his method needs $O(n^2)$ modular exponentiation per one participant. It is very high computational cost and is not fit for the scalable cryptosystem. In this paper, we propose the efficient share renewal scheme that need only O(n) modular exponentiation per participant. And we prove our scheme is secure if less than img ${\frac{1}{2}}$ n-1 adversaries exist and they are static adversary.

• KIPS Transactions on Computer and Communication Systems
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• v.13 no.1
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• pp.31-37
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• 2024

Conventional secret sharing techniques often derive shares from randomly generated polynomials or planes, resulting in lengthy and complex shares that are challenging to memorize and/or manage without the aid of a separate computer or specialized device. Modifying existing secret sharing methods to use a predetermined value, such as a memorizable password or bio-metric information, offers a solution. However, this approach raises concerns about security, especially when the predetermined value lacks randomness or has low entropy. In such cases, adversaries may deduce a secret S with just (t - 1) shares by guessing the predetermined value or employing brute force attacks. In this paper, we introduce a share hardening method designed to ensure the security of secret sharing while enabling the use of memorizable passwords or biometric information as predetermined shares.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.544-546
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• 2002

비밀분산법이란 하나의 비밀정보(secret)를 분산시켜 다수의 참가자에게 공유시키고, 필요시 허가된 참가자 부분집합만이 비밀정보를 복원할 수 있는 암호 프로토콜이다. 다양한 접근구조를 반영하는 비밀분산법이 제안되었는데 본 논문에서는 계층구조에 적용이 가능하면서 재사용이 가능한 새로운 비밀분산법을 제안한다. 즉, 참가자들은 트리 상의 상위 레벨부터 비밀정보의 복원에 대한 우선권을 갖고, 상위 레벨에 속하는 참가자들이 부재 시에는 하위 레벨에 속하는 자식 노드들에게 위임티켓(delegation ticket)을 전송하여 비밀정보의 복원 권한을 위임할 수 있고, 각 참가자가 하나의 비밀조각으로 서로 다른 비밀정보를 복원하는데 참여할 수 있도록 함으로써, 계층그룹에서 비밀조각의 재사용이 가능하도록 한다.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.5
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• pp.472-476
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• 2008

In this paper, we propose a simple and user friendly visual secret sharing scheme based on binary image. The proposed scheme is a new information hiding method which uses only bit-wise exclusive-or (XOR) operation and NOT operation to share a secret binary image information in the user friendly binary images. The proposed scheme has the following merits: (1) It provides efficient embedding and reconstruction algorithms. (2) It provides lossless and perfect reconstruction of the secret binary image. (3) It provides the detection method of its own group by sharing the user friendly image. (4) It can share same sized secret image such as original cover image unlike previous methods.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.6
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• pp.1037-1044
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• 2014

A (t,n) threshold secret sharing scheme is the scheme which allows a trusted party to distribute the shares among n participants in such a way that any t of them can recover the original secret, but any group knowing only t-1 or fewer shares can not. Recently, Eslami et al. and Tadayon et al. proposed threshold multi-secret sharing schemes, respectively. They proposed that their schemes don't require secure channels. But, without secure channels in their schemes, everyone can get the shares and find the secrets. The proposed scheme does not use secure channels and only t participants can solve the equations of the system from the delivered share shadows and find the secrets.