• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.11
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• pp.2235-2253
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• 2011

Digital document file such as Adobe Acrobat or MS-Office is encrypted by its own ciphering algorithm with a user password. When this password is not known to a user or a forensic inspector, it is necessary to recover the password to open the encrypted file. Password cracking by brute-force search is a perfect approach to discover the password but a time consuming process. This paper presents a new method of speeding up password recovery on Graphic Processing Unit (GPU) using a Compute Unified Device Architecture (CUDA). PDF files are chosen as a password cracking target, and the Abode Acrobat password recovery algorithm is examined. Experimental results show that the proposed method gives high performance at low cost, with a cluster of GPU nodes significantly speeding up the password recovery by exploiting a number of computing nodes. Password cracking performance is increased linearly in proportion to the number of computing nodes and GPUs.

• The Journal of Society for e-Business Studies
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• v.16 no.4
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• pp.1-16
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• 2011

A digital certificate mandated by the Electronic Signature Act has become familiar in our daily lives as 95% of the economically active population hold certificates. Due to upgrades to 256 bit level security that have become effective recently, the security and reliability of digital certificates are expected to increase. Digital certificates based on Public Key Infrastructure (PKI) have been known as "no big problem," but the possibility of password exposure in cases of leaked digital certificates still exists. To minimize this vulnerability, various existing studies have introduced alternative password methods, expansion of certificate storage media, and multiple certification methods. These methods perform enhanced functions but also have limitations including the fact that the secureness of passwords is not guaranteed. This study suggests an alternative method for enhancing the level of password secureness as a way to improve password security. This new method improves security management and enhances the convenience of using digital technologies. The results may be used for developing digital certificate related security technologies and research in the future.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06d
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• pp.82-85
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• 2011

개인정보를 사용자 몰래 뒤에서 훔쳐보거나 불법 카메라를 이용하여 녹화하는 등의 방식으로 얻어내는 훔쳐보기 공격(Shoulder-surfing attack)은 최근 모바일 기기의 보급 속도가 빨라지고 휴대성이 증대되면서 점점 더 큰 보안 문제로 떠오르고 있다. 본 논문에서는 그래픽 패스워드(Graphic Password) 방식 중에 훔쳐보기 공격을 효율적으로 막을 수 있는 새로운 방안을 소개하려고 한다. 이 방식은 그래픽 패스워드에서 쓰이는 패스 이미지(Pass image)의 선택을 한붓그리기를 이용하여 입력하는 방식으로써 기존의 방식들에 비해서 훔쳐보기 공격에 특화되어 좀 더 안전한 수준의 보안을 제공한다.

• Journal of the Korea Convergence Society
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• v.10 no.12
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• pp.63-69
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• 2019

Using a smartphone allows quick and easy authentication and payment. However, smartphone security threats are evolving into a variety of new hacking technologies, and are changing to attacks specific to the mobile environment. Therefore, there is a demand for an authentication method suitable for a mobile environment. In order to solve security weaknesses in knowledge-based authentication, many companies provide two-step authentication services such as OTP(One Time Password) to provide authentication services such as finance, games, and login. Although OTP service is easy to use, it is easy to duplicate random number table and has a disadvantage that can be reused because it is used as valid value within time limit. In this paper, we propose a mechanism that enables users to quickly and easily authenticate with high security using the authentication method that recognizes special characters through smartphone's dedicated application.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.6
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• pp.1361-1373
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• 2016

Recently the need for user authentication with increasing, there are a variety of mechanisms, such as password, graphic authentication, token, biometrics and multiple authentication. in particular, the data of the 2-dimensional(2D) factors such as password, graphic authentication, biometrics is used because of the convenience. The stored information is problematic in that additional data recording needs to be performed whenever authentication data is updated. Furthermore, this storage method is problematic in that the time it takes to perform authentication increases because the time it takes to compare storage data with authentication data increases in proportion to an increase in the amount of the storage data. Accordingly, authentication through the rapid comparison of storage data with authentication data is a very important factor in data recording and authentication technology using memory. Using the three-dimensional(3D) optical memory by variously changing the recoding elements during recoding of data constitutes the way that multiple recoding different data storage. This enables high-density recoding in this way, and by applying the possible parallel processing at the time of recording and restoring method, provided that it is possible to quickly record and restore the data. In addition, each time to solve problems that require additional data recorded by a combination of the stored data record in the old data using a combination of the authentication. The proposed mechanism is proposed an authentication method using scheme after the recoding data in 3D optical memory to apply the conditions corresponding to the recoding condition when restoring the recorded data and through the experiment it was confirmed possible application as an authentication mechanism.