• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.6
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• pp.1157-1169
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• 2021

The disaster recovery refers to policies and procedures to ensure continuity of services and minimize loss of resources and finances in case of emergency situations such as natural disasters. In particular, the disaster recovery method by the cloud service provider has advantages such as management flexibility, high availability, and cost effectiveness. However, this method has a dependency on a service provider and has a structural limitation in which a user cannot be involved in personal data. In this paper, we propose a protocol using proxy re-encryption for data confidentiality by removing dependency on service providers by backing up user data using blockchain and distributed storage. The proposed method is implemented in Ethereum and IPFS environments, and presents the performance and cost required for backup and recovery operations.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.3
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• pp.105-108
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• 2015

In this paper, we propose a differential fault analysis on symmetric SPN block cipher with bitslice involution S-box in 2011. The target block cipher was designed using AES block cipher and has advantage about restricted hardware and software environment using the same structure in encryption and decryption. Therefore, the target block cipher must be secure for the side-channel attacks. However, to recover the 128-bit secret key of the targer block cipher, this attack requires only one random byte fault and an exhausted search of $2^8$. This is the first known cryptanalytic result on the target block cipher.

• Journal of Advanced Navigation Technology
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• v.16 no.5
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• pp.787-793
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• 2012

Piccolo-128 is a 64-bit ultra-light block cipher suitable for the constrained environments such as wireless sensor network environments. In this paper, we propose biclique cryptanalysis on the full Piccolo-128. To recover the secret key of Piccolo-128, the proposed attack requires $2^{24}$ chosen plaintexts and the computational complexity of about $2^{127.35}$. This result is the first known theoretical attack result on the full Piccolo-128.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.7
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• pp.311-316
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• 2013

256-bit block cipher XSB(eXtended Spn Block cipher) was proposed in 2012 and has a symmetric strucrure in encryption and decryption process. In this paper, we propose a differential fault analysis on XSB. Based on a random byte fault model, our attack can recover the secret key of XSB by using only two random byte fault injection. This result is the first known cryptanalytic result on the target algorithm.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.151-153
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• 2001

문선 채널에서 신뢰성 있는 실시간 동영상 서비스를 하기 위해서는 비디오 스트림 내에서 오류가 발생한 블록의 위치를 알아야 정확한 오류 복구가 가능하다. 이전의 오류 검출 연구들은 대부분 픽셀 단위로 비교하므로 계산량이 많은 문제점이 있다. 본 논문에서는 실시간 서비스를 고려하여 계산량이 적은 블록 단위의 오류 검출 기법을 제안한다. 블록 내의 DCT 계수를 이용하여 오류를 검출한다. DC 계수를 이용해 1차 임계치를 비교한 후 AC 계수를 이용해 에지를 검출한다. 애지가 존재하는 블록에 대해 2차 임계치를 비교하여 오류 여부를 판단한다. DCT 계수 정보를 직접 이용할 수 없는 P, B 프레임에서 DCT 계수를 추정할 수 있는 방법도 함께 제안한다. 제안한 오류 검출 기법을 실제 구현하여 성능을 측정한다.

• Journal of Advanced Navigation Technology
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• v.17 no.5
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• pp.568-573
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• 2013

In this paper, we propose a differential fault analysis on symmetry structured SPN block cipher proposed in 2008. The target algorithm has the SPN structure and a symmetric structure in encryption and decryption process. To recover the 128-bit secret key of the target algorithm, this attack requires only one random byte fault and an exhaustive search of $2^8$. This is the first known cryptanalytic result on the target algorithm.

• Journal of Venture Innovation
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• v.2 no.2
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• pp.21-29
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• 2019

In the public certificate technology commonly used in Korea, users have a cumbersome problem of always resetting when they forget their password. In this paper, as a solution to this problem, we propose a secure authentication certificate password recovery protocol using blockchain, PKI, and DID for distributed storage. DID is a schema for protecting block ID in blockchain system. The private key used in the PKI is configured as a user's biometric, for example, a fingerprint, so that it can completely replace the memory of the complex private key. To this end, based on the FIDO authentication technology that most users currently use on their smartphones, the process of authenticating a user to access data inside the block minimizes the risk of an attacker taking over the data.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.208-208
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• 2004

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.842-846
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• 2015

In this study, we propose an algorithm of the method of recovering quickly find the location of the error encountered during separate operations in the functional structure of complex digital circuits by mimicking the self-healing function of the cell. By the digital circuit was divided by 9 function block unit of function, proposes a method that It can quickly detect and recover the error position. It was the detection and recovery algorithms for the error location in the digital circuit of a complicated structure and could extended the number of function block for the $3{\times}3$ matrix structure on the digital circuit.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.4
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• pp.803-807
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• 2018

The Fantomas and the Robin are the block ciphers included in the LS-designs, the family of block ciphers. They are designed to efficiently apply the masking technique, which is a side-channel analysis countermeasure technique, using L-boxes and S-boxes capable of bit slice implementation. In this paper, we show that the key recovery attacks of Fantomas and Robin through the related-key differential analysis are possible with $2^{56}$ and $2^{72}$ time complexity, $2^{56}$ and $2^{69}$ chosen plaintext respectively.