• Journal of Information Processing Systems
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• v.13 no.3
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• pp.573-589
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• 2017

Cloud computing is an attractive solution that can provide low cost storage and powerful processing capabilities for government agencies or enterprises of small and medium size. Yet the confidentiality of information should be considered by any organization migrating to cloud, which makes the research on relational database system based on encryption schemes to preserve the integrity and confidentiality of data in cloud be an interesting subject. So far there have been various solutions for realizing SQL queries on encrypted data in cloud without decryption in advance, where generally homomorphic encryption algorithm is applied to support queries with aggregate functions or numerical computation. But the existing homomorphic encryption algorithms cannot encrypt floating-point numbers. So in this paper, we present a mechanism to enable the trusted party to encrypt the floating-points by homomorphic encryption algorithm and partial trusty server to perform summation on their ciphertexts without revealing the data itself. In the first step, we encode floating-point numbers to hide the decimal points and the positive or negative signs. Then, the codes of floating-point numbers are encrypted by homomorphic encryption algorithm and stored as sequences in cloud. Finally, we use the data structure of DoubleListTree to implement the aggregate function of SUM and later do some extra processes to accomplish the summation.

• Journal of Korea Multimedia Society
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• v.20 no.12
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• pp.1913-1927
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• 2017

Encryption technology is to hide information in a cyberspace built using a computer and to prevent third parties from changing it. If a malicious user accesses unauthorized device or application services on the Internet of objects, it may be exposed to various security threats such as data leakage, denial of service, and privacy violation. One way to deal with these security threats is to encrypt and deliver the data generated by a user. Encrypting data must be referred to a technique of changing data using a complicated algorithm so that no one else knows the content except for those with special knowledge. As computers process computations that can be done at a very high speed, current cryptographic techniques are vulnerable to future computer performance improvements. We designed and implemented a new encryption program that combines ancient and modern cryptography so that the user never knows about data management, and transmission. The significance of this paper is that it is the safest method to combine various kinds of encryption methods to secure the weaknesses of the used cryptographic algorithms.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.12
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• pp.6116-6132
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• 2017

The proxy re-encryption allows an intermediate proxy to convert a ciphertext for Alice into a ciphertext for Bob without seeing the original message and leaking out relevant information. Unlike many prior identity based proxy re-encryption schemes which are based on the number theoretic assumptions such as large integer factorization and discrete logarithm problem. In this paper, we first propose a novel identity based proxy re-encryption scheme which is based on the hardness of standard Learning With Error(LWE) problem and is CPA secure in the standard model. This scheme can be reduced to the worst-case lattice hard problem that is able to resist attacks from quantum algorithm. The key step in our construction is that the challenger how to answer the private query under a known trapdoor matrix. Our scheme enjoys properties of the non-interactivity, unidirectionality, anonymous and so on. In this paper, we utilize primitives include G-trapdoor for lattice and sample algorithms to realize simple and efficient re-encryption.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.2
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• pp.41-49
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• 2016

Lossless encryption methods are more applicable than lossy encryption methods when marginal distortion is not tolerable. In this research, the author propose a novel lossless symmetric key encryption/decryption technique. In the proposed algorithm, the image is transformed into the frequency domain using the lifting wavelet transform, then the image sub-bands are encrypted in a such way that guarantees a secure, reliable, and an unbreakable form. The encryption involves scattering the distinguishable frequency data in the image using a reversible weighting factor amongst the rest of the frequencies. The algorithm is designed to shuffle and reverse the sign of each frequency in the transformed image before the image frequencies are transformed back to the pixel domain. The results show a total deviation in pixel values between the original and encrypted image. The decryption algorithm reverses the encryption process and restores the image to its original form. The proposed algorithm is evaluated using standard security and statistical methods; results show that the proposed work is resistant to most known attacks and more secure than other algorithms in the cryptography domain.

• Smart Media Journal
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• v.4 no.4
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• pp.39-46
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• 2015

This paper describes hardware implementation of the encryption block of the '128 bit block cipher LEA' among various lightweight encryption algorithms for IoT (Internet of Things) security. Round function blocks and key-schedule blocks are designed by parallel circuits for high throughput. The encryption blocks support secret-key of 128 bits, and are designed by FSM method and 24/n stage(n=1, 2, 3, 4, 8, 12) pipeline methods. The LEA-128 encryption blocks are modeled using Verilog-HDL and implemented on FPGA, and according to the synthesis results, minimum area and maximum throughput are provided.

• Journal of the Korean Data and Information Science Society
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• v.25 no.6
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• pp.1419-1429
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• 2014

In this paper, we consider the development of encryption of DES (data encryption standard) based on Microsoft Excel Macro, which was adopted as the FIPS (federal information processing standard) 46 of USA in 1977. Concrete explanation of DES is given. Algorithms for DES encryption are adapted to Excel Macro. By repeating the 16 round which is consisted of diffusion (which hide the relation between plain text and cipher text) and the confusion (which hide the relation between cipher key and cipher text) with Excel Macro, we can easily get the desired DES cipher text.

• Journal of Korea Society of Digital Industry and Information Management
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• v.14 no.2
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• pp.49-59
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• 2018

Encryption of digital images has been requested various fields. In the meantime, many algorithms based on a text - based encryption algorithm have been proposed. In this paper, we propose a method of encryption in wavelet transform domain to utilize the characteristics of digital image. In particular, wavelet transform is used to reduce the association between the encrypted image and the original image. Wavelet packet transformations can be decomposed into more subband images than wavelet transform, and various position permutation, numerical transformation, and visual transformation are performed on the coefficients of this subband image. As a result, this paper proposes a method that satisfies the characteristics of high encryption strength than the conventional wavelet transform and reversibility. This method also satisfies the lossless symmetric key encryption and decryption algorithm. The performance of the proposed method is confirmed by visual and quantitative. Experimental results show that the visually encrypted image is seen as a completely different signal from the original image. We also confirmed that the proposed method shows lower values of cross correlation than conventional wavelet transform. And PSNR has a sufficiently high value in terms of decoding performance of the proposed method. In this paper, we also proposed that the degree of correlation of the encrypted image can be controlled by adjusting the number of wavelet transform steps according to the characteristics of the image.

• Journal of Advanced Navigation Technology
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• v.20 no.1
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• pp.72-78
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• 2016

MD-5 has been the hash algorithm to encrypt the user's password on Linux from the beginning. Recently the more reliable password management was demanded and SHA-512 algorithm became the hash algorithm on the recent Enterprise Linux which is more reliable than MD-5. This paper researching the characteristics of the hashing and encryption algorithms and find out about Linux User information management. Based on this analysis, and analysis of the security of the hashing algorithm is applied to the user password. In addition, analyzes the cases used hash algorithm applied to the validation of Open Source Software file, such as Apache, PHP, MySQL. Finally, by analyzing the security tool John The Ripper this paper suggests the enhanced security with the administrative management of passwords.

• International Journal of Computer Science & Network Security
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• v.22 no.6
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• pp.310-318
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• 2022

Job offers have become more widespread and it has become easier and faster to apply for jobs through electronic recruitment platforms. In order to increase the protection of the data that is attached to the recruitment platforms. In this research, a proposed model was created through the use of hybrid encryption, which is used through the following algorithms: AES,Twofish,. This proposed model proved the effectiveness of using hybrid encryption in protecting personal data.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.940-943
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• 2002

This paper presents hardware implementations of the two representative cryptographic algorithms, Advanced Encryption Standard (Rijndael), and the present American federal standard (Triple DES) using a PCI- based FPGA board named "EBSW-1" This board bases on a FPGA chip (Xilinx Virtex300 XCV300PQ240-4). The implementation results of these two algorithms were tested successfully. AES circuit could proceed an encryption as well as a decryption two times faster than the Triple-DES circuit, while the former circuit used higher rates of CLBs. Besides, if these architectures use pipeline-registers, the processing speed will be increased about 1.5 times than the presented circuits.