• Journal of the Optical Society of Korea
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• 제20권1호
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• pp.55-63
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• 2016

In this paper, a new asymmetric public key cryptography based on the modified RSA algorithm is proposed by using logic-based optical processing. The proposed asymmetric public key algorithm is realized into an optical schematic, where AND, OR and XOR logic operations are implemented by using free space digital optics architecture. Schematically, the proposed optical configuration has an advantage of generating the public keys simultaneously. Another advantage is that the suggested optical setup can also be used for message encryption and decryption by simply replacing data inputs of SLMs in the optical configuration. The last merit is that the optical configuration has a 2-D array data format which can increase the key length easily. This can provide longer 2-D key length resulting in a higher security cryptosystem than the conventional 1-D key length cryptosystem. Results of numerical simulation and differential cryptanalysis are presented to verify that the proposed method shows the effectiveness in the optical asymmetric cryptographic system.

• Current Optics and Photonics
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• 제4권2호
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• pp.103-114
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• 2020

A new optical asymmetric cryptosystem is proposed by modifying the asymmetric RSA public-key protocol required in a cryptosystem. The proposed asymmetric public-key algorithm can be optically implemented by combining a two-step quadrature phase-shifting digital holographic encryption method with the modified RSA public-key algorithm; then two pairs of public-private keys are used to encrypt and decrypt the plaintext. Public keys and ciphertexts are digital holograms that are Fourier-transform holograms, and are recorded on CCDs with 256-gray-level quantized intensities in the optical architecture. The plaintext can only be decrypted by the private keys, which are acquired by the corresponding asymmetric public-key-generation algorithm. Schematically, the proposed optical architecture has the advantage of producing a complicated, asymmetric public-key cryptosystem that can enhance security strength compared to the conventional electronic RSA public-key cryptosystem. Numerical simulations are carried out to demonstrate the validity and effectiveness of the proposed method, by evaluating decryption performance and analysis. The proposed method shows feasibility for application to an asymmetric public-key cryptosystem.

• 정보보호학회논문지
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• 제27권3호
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• pp.459-466
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• 2017

가장 널리 사용되는 오픈 소스 프로젝트 중 하나인 OpenSSL은 대부분의 웹 사이트, 서버 및 클라이언트를 보호하는 데 사용되는 암호화 라이브러리이다. OpenLLS을 사용하여 SSL 혹은 이것으로부터 나온 TLS 프로토콜로 안전하게 통신할 수 있다. 시스템의 지속적 보안성 유지를 위해 암호 프로토콜은 업데이트되고 개선되어야 하므로, 이 라이브러리는 새로운 암호화 방법을, 특히 대칭 암호화 프로토콜을, 시스템에 통합하여 구현하는 일이 간단하도록 작성되었다. 그러나 비대칭 암호화 프로토콜을 추가 할 때는 훨씬 더 복잡해진다. 본 논문에서는 OpenSSL 기반 사용자 지정 암호 프로토콜 구현 방안 도출을 위하여 OpenSSL 라이브러리의 세부 아키텍처를 파악하고 설명한다. 그리고 대칭키와 비대칭 암호화 기반 사용자 지정 프로토콜을 수용하기 위해 OpenSSL 라이브러리를 수정하는 방법을 제시한다.

• Journal of applied mathematics & informatics
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• 제8권3호
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• pp.943-957
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• 2001

In this paper, we propose an efficient encryption algorithm, without exchanging session keys of a symmetric cryptosystem. The proposed scheme, called as the FAKE(Fast Asymmetric Key Encryption), first scrambles an entire input message and then encrypts small parts of the scrambled message using an asymmetric key encryption scheme. We use the all-or-nothing transform based on the hash function as a scrambling function, which was proposed by Shin, et al. Furthermore, the proposed scheme can additionally provide a digital signature service with only small overhead.

• International Journal of Computer Science & Network Security
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• 제21권9호
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• pp.41-50
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• 2021

Cloud computing is one of the most expanding technologies nowadays; it offers many benefits that make it more cost-effective and more reliable in the business. This paper highlights the various benefits of cloud computing and discusses different cryptography algorithms being used to secure communications in cloud computing environments. Moreover, this thesis aims to propose some improvements to enhance the security and safety of cloud computing technologies.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권12호
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• pp.3352-3365
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• 2012

Group key agreement (GKA) is a cryptographic primitive allowing two or more users to negotiate a shared session key over public networks. Wu et al. recently introduced the concept of asymmetric GKA that allows a group of users to negotiate a common public key, while each user only needs to hold his/her respective private key. However, Wu et al.'s protocol can not resist active attacks, such as fabrication. To solve this problem, Zhang et al. proposed an authenticated asymmetric GKA protocol, where each user is authenticated during the negotiation process, so it can resist active attacks. Whereas, Zhang et al.'s protocol needs a partially trusted certificate authority to issue certificates, which brings a heavy certificate management burden. To eliminate such cost, Zhang et al. constructed another protocol in identity-based setting. Unfortunately, it suffers from the so-called key escrow problem. In this paper, we propose the certificateless authenticated asymmetric group key agreement protocol which does not have certificate management burden and key escrow problem. Besides, our protocol achieves known-key security, unknown key-share security, key-compromise impersonation security, and key control security. Our simulation based on the pairing-based cryptography (PBC) library shows that this protocol is efficient and practical.

• 한국멀티미디어학회논문지
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• 제25권7호
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• pp.922-931
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• 2022

Recently, the need for health information management platforms has been increasing for efficient medical and IT technology research. However, health information is requiring security management by law. When permissioned blockchain technology is used to manage health information, the integrity is provided because only the authenticated users participate in bock generation. However, if the blockchain server is attacked, it is difficult to provide security because user authentication, block generation, and block verification are all performed on the blockchain server. In this paper, therefore, we propose a Health Information Management Server, which uses a permissioned blockchain algorithm and asymmetric cryptography. Health information is managed as a blockchain transaction to maintain the integrity, and the actual data are encrypted with an asymmetric key. Since using a private key kept in the institute local environment, the data confidentiality is maintained, even if the server is attacked. 1,000 transactions were requested, as a result, it was found that the server's average response time was 6,140ms, and the average turnaround time of bock generation was 368ms, which were excellent compared to those of conventional technology. This paper is that a model was proposed to overcome the limitations of permissioned blockchains.

• 한국산학기술학회논문지
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• 제12권5호
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• pp.2322-2326
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• 2011

기존 암호시스템은 비도를 증가시키기 위하여 데이터와 키 값을 별도로 사용하고 일정 횟수의 반복성을 수행하며 무한수열에 가까운 LFSR의 주기특성을 증가시키므로 암호시스템의 효율이 저하되는 문제점이 있다. 본 논문에서 제안된 알고리즘은 대칭형 암호방식에 비대칭형 암호개념을 적용한 새로운 기능의 데이터 재배열, 치환, 데이터 암호블록, 키 스케쥴러로 구성하였다. 본 논문에서 제안된 암호알고리즘은 범용 SYNOPSYS를 이용하여 스마트 카드의 암호시스템을 설계하였고 40MHz의 시스템 속도로 ALTERA MAX+PlUS II 툴의 모의실험한 결과 단일 라운드로 16 라운드의 비도와 640Mbps의 데이터 처리율로 AES보다 52% 향상됨 확인하였다.

• 한국정보통신학회논문지
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• 제16권11호
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• pp.2347-2354
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• 2012

안드로이드 상에서의 프로그램 개발은 JAVA SDK를 통해 이루어진다. 하지만 JAVA의 사용은 virtual machine 상에서의 동작으로 인해 기존의 C언어에 비해 성능이 떨어지는 단점을 가진다. 최근에는 이러한 문제점을 해결하기 위해 NDK를 이용한 최적화 프로그램 개발이 사용되고 있다. 해당 기법은 안드로이드 프로그램을 C언어로 작성하여 연산을 효율적으로 수행한다. 본 논문에서는 안드로이드 상에서의 공개키 기반 암호화를 비교 분석하기 위해 NDK와 SDK를 사용하여 곱셈을 구현한다. SDK의 구현에는 BigInteger 패키지를 사용하였으며 NDK의 구현에는 Comb method를 사용하였다. 또한 안드로이드 상에서의 사칙연산, 조건문 그리고 호출문의 연산 수행 결과를 비교하여 NDK를 통한 성능향상에 대해 알아본다.

• 한국산학기술학회논문지
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• 제11권12호
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• pp.4962-4967
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• 2010

스마트 카드는 암호알고리즘의 개발과 더불어 전자상거래 환경이 구축되면서 가치이전의 수단 및 활용분야가 다양하기 때문에 정보 통신망 환경에서 중요한 보안 장치로 수요나 활용면에서 급격한 증가율을 보이고 있다. 따라서 본 논문에서 제안한 스마트 카드용 키 스케쥴러 블록은 다양한 멀티미디어 및 실시간 통신의 암호시스템에 적용할 경우 기존시스템과 호환성이 용이하여 하드웨어 설계와 비도 및 처리속도를 향상시킬 수 있다고 사료된다.