• Proceedings of the Optical Society of Korea Conference
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• 2002.11a
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• pp.60-61
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• 2002

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.450-453
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• 2002

In this paper a Phase-based virtual image encryption and decryption techniques based on a joint transform correlator (JTC) are proposed. In this method, an encrypted image is obtained by multiplying a phase-encoded virtual image that contains no information from the decrypted image with a random phase. Even if this encryption process converts a virtual image into a white-noise-like image, the unauthorized users can permit a counterfeiting of the encrypted image by analyzing the random phase mask using some phase-contrast technique. However, they cannot reconstruct the required image because the virtual image protects the original image from counterfeiting and unauthorized access. The proposed encryption technique does not suffer from strong auto-correlation terms appearing in the output plane. In addition, the reconstructed data can be directly transmitted to a digital system for real-time processing. Based on computer simulations, the proposed encryption technique and decoding system were demonstrated as adequate for optical security applications.

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.477-484
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• 2014

In this paper, we propose a new optical secret key sharing method based on the Diffie-Hellman key exchange protocol required in cipher system. The proposed method is optically implemented by using a free-space interconnected optical logic gate technique in order to process XOR logic operations in parallel. Also, we present a compact type of optical module which can perform the modified Diffie-Hellman key exchange for a cryptographic system. Schematically, the proposed optical configuration has an advantage of producing an open public key and a shared secret key simultaneously. Another advantage is that our proposed key exchange system uses a similarity to double key encryption techniques to enhance security strength. This can provide a higher security cryptosystem than the conventional Diffie-Hellman key exchange protocol due to the complexity of the shared secret key. Results of numerical simulation are presented to verify the proposed method and show the effectiveness in the modified Diffie-Hellman key exchange system.

• Journal of the Optical Society of Korea
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• v.20 no.2
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• pp.228-233
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• 2016

In this paper, we propose a nonlinear maximum average correlation height (MACH) filter for information authentication of photon counting double random phase encryption (DRPE). To enhance the security of DRPE, photon counting imaging can be applied because of its sparseness. However, under severely photon-starved conditions, information authentication of DRPE may not be implemented successfully. To visualize the photon counting DRPE, a three-dimensional imaging technique such as integral imaging can be used. In addition, a nonlinear MACH filter can be utilized for helping the information authentication. Therefore, in this paper, we use integral imaging and nonlinear MACH filter to implement the information authentication of photon counting DRPE. To verify our method, we implement optical experiments and computer simulation.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.3
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• pp.63-69
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• 2001

Smartcard is highlighted as infrastructure that has an excellent security for executing functions such as user authentication, access control, information storage and control, and its market is expanding rapidly. But possibilities of forgery and alteration by hacking are increasing as well. This paper proposes a method to prevent card forgery and alteration using angular multiplexing and private key multiplexing method on optical encryption, and proposed a Public Key Infrastructure(PKI)-based authentication system combined with One-Time Password (OTP) for verification of forgery and alteration .

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.63-66
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• 2001

In this paper a binary image encryption technique and decryption system based on a joint transform correlator (JTC) are Proposed. In this method, a Fourier transform of the encrypted image is used as the encrypted data and a Fourier transform of the random phase is used as the key code. The original binary image can be reconstructed on a square law device, such as a CCD camera after the joint input is inverse Fourier transformed. The proposed encryption technique does not suffer from strong auto-correlation terms appearing in the output plane. Based on computer simulations, the proposed encryption technique and decoding system were demonstrated as adequate for optical security applications.

• Journal of the Optical Society of Korea
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• v.17 no.5
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• pp.384-391
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• 2013

We propose a split-encryption scheme on converting original images to multiple ciphertexts. This conversion introduces one random phase-only function (POF) to influence phase distribution of the preliminary ciphertexts. In the encryption process, the original image is mathematically split into two POFs. Then, they are modulated on a spatial light modulator one after another. And subsequently two final ciphertexts are generated by utilizing two-step phase-shifting interferometry. In the decryption process, a high-quality reconstructed image with relative error $RE=7.6061{\times}10^{-31}$ can be achieved only when the summation of the two ciphertexts is Fresnel-transformed to the reconstructed plane. During the verification process, any silhouette information was invisible in the two reconstructed images from different single ciphertexts. Both of the two single REs are more than 0.6, which is better than in previous research. Moreover, this proposed scheme works well with gray images.

• Current Optics and Photonics
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• v.6 no.6
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• pp.565-575
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• 2022

In this paper, we propose a non-fungible token (NFT) transaction method that can commercialize the real 3D property and make property sharing possible using the 3D reconstruction technique. In addition, our proposed method enhances the security of NFT copyright and metadata by using optical encryption. In general, a conventional NFT is used for 2D image proprietorial rights. To expand the scope of the use of tokens, many cryptocurrency industries are currently trying to apply tokens to real three-dimensional (3D) property. However, many token markets have an art copyright problem. Many tokens have been minted without considering copyrights. Therefore, tokenizing real property can cause significant social issues. In addition, there are not enough methods to mint 3D real property for NFT commercialization and sharing property tokens. Therefore, we propose a new token management technique to solve these problems using integral imaging and double random phase encryption. To show our system, we conduct a private NFT market using a test blockchain network that can demonstrate the whole NFT transaction process.

• Current Optics and Photonics
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• v.4 no.6
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• pp.483-499
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• 2020

In this paper, a novel analog signature scheme is proposed by modifying an RSA-based digital signature scheme with optical phase-shifting digital holography. The purpose of the proposed method is generating an analog signature to provide data confidentiality and security during the data transfer, compared to the digital signature. The holographic encryption technique applied to a hash value reveals an analog-type of pseudo-random pattern in the analog signature scheme. The public key and secret key needed to verify the analog signature are computed from public key ciphers which are generated by the same holographic encryption. The proposed analog signature scheme contains a kind of double encryption in the process of generating signature and key, which enhances security level more than the digital signature. The results of performance simulations show the feasibility of the highly secure signature scheme, and security analysis shows high robustness against known-message attacks and chosen-message attacks. In addition, the proposed method can apply to one-time signature schemes which can be used to sign only one message and it can also apply to authentication, e-mails, electronic banking and electronic data interchange.

• Journal of Korea Multimedia Society
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• v.25 no.8
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• pp.983-990
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• 2022

In this paper, we implemented a hierarchical encryption system using two-step phase-shifting digital holography(PSDH) technology based on XOR and scramble operations. The proposed encryption system is a system that authenticates access through the issuance of an encryption key for access to individual laboratories, department offices, and universities. In the encryption process, we proposed a double encryption method using XOR and scramble operation with digital technology and two-step phase-shifting digital holography with optical technology. In the two-step PSDH process, an new method of determining the reference wave intensity without measuring it by using random common object image gererated from digital encryption process was also proposed. In the decryption process, the process is performed in the reverse order of encryption process. And only when the various key information used in the encryption process is correct, the encrypted information can be decrypted, so that the user can access the desired place. That is, there is a feature that can hierarchically control the space that can be accessed according to the type of key issued in the proposed encryption system. Through the computer simulation, the feasibility of the proposed hierarchical encryption system was confirmed.