• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.9
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• pp.658-665
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• 2003

In this paper, we propose an improved image encryption and the shift-tolerance method in the Fourier space using a virtual phase image. The encrypted image is obtained by the Fourier transform of the product of a phase-encoded virtual image, not an original image, and a random phase image. Therefore, even if unauthorized users analyze the encrypted image, we can prevent the possibility of counterfeiting from unauthorized people using virtual image which dose not contain any information from the original image. The decryption technique is simply performed by inverse Fourier transform of the interference pattern between the encrypted image and the Fourier decrypting key, made of proposed phase assignment rule, in frequency domain. We demonstrate the robustness to noise, to data loss and shift of the encrypted image or the Fourier decryption key in the proposed technique.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1653-1660
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• 2010

The user information stored in database have been leaked frequently. To protect information against malevolent manager on the inside or outside aggressor, it is one of the most efficient way to encrypt information and store to database. It is better to destruct information than not to use encrypted information stored in database. The encrypted database search system is developed variously, and used widely in many fields. In this paper, we implemented the scheme that can search encrypted document without exposing user's information to the untrusted server in mobile device. We compared and analyzed the result embodied with DES, AES, and ARIA based on symmetric key by searching time.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.1
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• pp.3-12
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• 2001

In this paper, a synchronized stream encryption system for secure link layer communication in a radio channel is designed. Interleaving scheme which is used to enhance the transmission performance over a fading channel is applied to the encrypted information. A designed synchronous scream cipher system consists of a keystream generator, a synchronization pattern generator and a session key generator. The structure of a synchronous stream cipher system with periodic synchronization is composed of the encrypted information which consists of a synchronization pattern, an error correcting coded session key, an encrypted data in a period of synchronization. In this paper, interleaving scheme using dynamic allocation a1gorithm(DAA) is applied the encrypted information. The BER of the DAA has been slightly higher than that of the SAA(static allocation algorithm).

• Annual Conference of KIPS
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• 2022.05a
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• pp.161-164
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• 2022

Homomorphic Encryption (HE) schemes have been recently growing as a reliable solution to preserve users' information owe to maintaining and operating the user data in the encrypted state. In addition to that, several Neural Networks models merged with HE schemes have been developed as a prospective tool for privacy-preserving machine learning. Those mentioned works demonstrated that it is possible to match the accuracy of non-encrypted models but there is always a trade-off in the computation time. In this work, we evaluate the implementation of CKKS HE scheme operations over the layers of a LeNet5 convolutional inference model, however, owing to the limitations of the evaluation environment, the scope of this work is not to develop a complete LeNet5 encrypted model. The evaluation was performed using the MNIST dataset with Microsoft SEAL (MSEAL) open-source homomorphic encryption library ported version on Python (PyFhel). The behavior of the encrypted model, the limitations faced and a small description of related and future work is also provided.

• Journal of the Optical Society of Korea
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• v.16 no.3
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• pp.263-269
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• 2012

In this paper, we propose a new dual optical encryption method for binary data and secret key based on 2-step phase-shifting digital holography for a cryptographic system. Schematically, the proposed optical setup contains two Mach-Zehnder type interferometers. The inner interferometer is used for encrypting the secret key with the common key, while the outer interferometer is used for encrypting the binary data with the same secret key. 2-step phase-shifting digital holograms, which result in the encrypted data, are acquired by moving the PZT mirror with phase step of 0 or ${\pi}/2$ in the reference beam path of the Mach-Zehnder type interferometer. The digital hologram with the encrypted information is a Fourier transform hologram and is recorded on CCD with 256 gray level quantized intensities. Computer experiments show the results to be encryption and decryption carried out with the proposed method. The decryption of binary secret key image and data image is performed successfully.

• Journal of the Optical Society of Korea
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• v.14 no.2
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• pp.97-103
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• 2010

We propose a new technique for the optical encryption of gray-level optical images digitized into 8-bits binary data by ASCII encoding followed by QPSK modulation. We made an encrypted digital hologram with a security key by using 2-step phase-shifting digital holography, and the encrypted digital hologram is recorded on a CCD camera with 256 gray-level quantized intensities. With these encrypted digital holograms, the phase values are reconstructed by the same security key and are decrypted into the original gray-level optical image by demodulation and decoding. Simulation results show that the proposed method can be used for cryptosystems and security systems.

• Proceedings of the KAIS Fall Conference
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• 2003.11a
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• pp.211-215
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• 2003

Network security should be first considered in a distributed computing environment with frequent information interchange through internet. Clear classification is needed for information users should protect and for information open outside. Basically proper encrypted database system should be constructed for information security, and security policy should be planned for each site. This paper describes access control, user authentication, and User Security and Encryption technology for the construction of database security system from network users. We propose model of network encrypted database security system for combining these elements through the analysis of operational and technological elements. Systematic combination of operational and technological elements with proposed model can construct encrypted database security system secured from unauthorized users in distributed computing environment.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.62-63
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• 2003

We propose an improved image encryption and the shift-tolerance method in the Fourier space using a virtual phase image. The encrypted image is obtained by the Fourier transform of the product of a phase-encoded virtual image, not an original image, and a random phase image. We demonstrate the robustness to noise, to data loss and shift of the encrypted image or the Fourier decryption key in the proposed technique.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1510-1532
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• 2017

In smart grid, privacy implications to individuals and their families are an important issue because of the fine-grained usage data collection. Wireless communications are utilized by many utility companies to obtain information. Network coding is exploited in smart grids, to enhance network performance in terms of throughput, delay, robustness, and energy consumption. However, random linear network coding introduces a new challenge for privacy preserving due to the encoding of data and updating of coefficients in forwarder nodes. We propose a distributed privacy preserving scheme for random linear network coding in smart grid that considers the converged flows character of the smart grid and exploits a homomorphic encryption function to decrease the complexities in the forwarder node. It offers a data confidentiality privacy preserving feature, which can efficiently thwart traffic analysis. The data of the packet is encrypted and the tag of the packet is encrypted by a homomorphic encryption function. The forwarder node random linearly codes the encrypted data and directly processes the cryptotext tags based on the homomorphism feature. Extensive security analysis and performance evaluations demonstrate the validity and efficiency of the proposed scheme.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.6
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• pp.1401-1414
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• 2018

The k-means clustering algorithm groups input data with the number of groups represented by variable k. In fact, this algorithm is particularly useful in market segmentation and medical research, suggesting its wide applicability. In this paper, we propose a privacy-preserving clustering algorithm that is appropriate for outsourced encrypted data, while exposing no information about the input data itself. Notably, our proposed model facilitates encryption of all data, which is a large advantage over existing privacy-preserving clustering algorithms which rely on multi-party computation over plaintext data stored on several servers. Our approach compares homomorphically encrypted ciphertexts to measure the distance between input data. Finally, we theoretically prove that our scheme guarantees the security of input data during computation, and also evaluate our communication and computation complexity in detail.