• Journal of information and communication convergence engineering
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• v.8 no.4
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• pp.433-436
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• 2010

In this paper, we presented a ciphering method whose target data is any kind of digital bit-stream. It uses a chaotic system as the main encrypting tool, MISR (Multi-Input Signature Register), and shift-and-rotation function, all of which are exclusive-ORed with the plaintext. Also, it incorporates a cipher text feedback mode such that part of the previously ciphered data is fed back to encrypt the current data. The encryption block size and the amount of feedback data are different at each ciphering operation. Experimental results with the image/video date showed that this method has enough speed and encryption effect with negligible latency time. Thus, we are expecting it to have various application areas that need high speed stream ciphering with high security level.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.603-611
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• 2013

In this paper, we propose a new method which estimates and encrypts significant component of digital image such as digital cinema using discrete wavelet packet transform (DWPT). After analyzing the characteristics of images in spatial and frequency domain, the required information for ciphering an image was extracted. Based on this information an ciphering method was proposed with wavelet transform and packetization of subbands. The proposed algorithm can encrypt images in various robust from selecting transform-level and energy threshold. From analyzing the encryption effect numerically and visually, the optimized parameter for encryption is presented. Without additional analyzing process, one can encrypt efficiently digital image using the proposed parameter. Although only 0.18% among total data is encrypted, the reconstructed image dose not identified. The paketization information of subbands and the cipher key can be used for the entire secret key.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1859-1862
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• 2003

Security of digital images attracts much attention recently, and many image encryption methods have been proposed. This paper proposed an image encryption methodology to hide the image information. The target data of it is the result from quantization in the wavelet domain. This method encrypts only part of the image data rather than the whole data of the original image. For ciphering the quantization index we use a novel image encryption Algorithm called BRIE(Bit Recirculation Image Encryption). which was proposed by J. C. Yen and J. I. Guo in 1999. According to a chaotic binary sequence generated by BRIE, the block which is produced by quantization index is cyclically shifted in the right or left direction. Finally, simulation results are included to demonstrate its effectiveness.

• ETRI Journal
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• v.28 no.2
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• pp.250-252
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• 2006

In this letter, a discrete state, discrete time chaotic pseudo random number generator (CPRNG) is presented for stream ciphering of text, audio, or image data. The CPRNG is treated as a finite state machine, and its state is modulated according to the input bit sequence of the signal to be encrypted. The modulated state sequence obtained can be transmitted as a spread spectrum or encrypted data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11C
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• pp.905-916
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• 2008

In this paper, we propose a new method which estimates and encrypts significant component of digital hologram using discrete wavelet packet transform (DWPT). After analyzing the characteristics of digital hologram in spatial and frequency domain, the required information for ciphering digital hologram was extracted. Based on this information an ciphering method was proposed with wavelet transform and packetization of subbands. The proposed algorithm can encrypt digital hologram in various robust from selecting transform-level and energy threshold. From analyzing the encryption effect numerically and visually, the optimized parameter for encryption is presented. Without additional analyzing process, one can encrypt efficiently digital hologram using the proposed parameter. Although only 0.032% among total data is encrypted, the reconstructed object dose not identified. The paketization information of subbands and the cipher key can be used for the entire secret key.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12C
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• pp.1193-1200
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• 2005

In this paper, we proposed an image hiding method which decreases the amount of calculation encrypting partial data rather than the whole image data using a discrete wavelet transform and a linear scalar quantization which have been adopted as the main technique in JPEG2000 standard and then implemented the proposed algorithm to hardware. A chaotic system was used instead of encryption algorithms to reduce further amount of calculation. It uses a method of random changing method using the chaotic system of the data in a selected subband. For ciphering the quantization index it uses a novel image encryption algorithm of cyclical shifting to the right or left direction and encrypts two quantization assignment method (Top-down coding and Reflection coding), made change of data less. The experiments have been performed with the proposed methods implemented in software for about 500 images. The hardware encryption system was synthesized to find the gate-level circuit with the Samsung $0.35{\mu}m$ Phantom-cell library and timing simulation was performed, which resulted in the stable operation in the frequency above 100MHz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2933-2942
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• 2015

This paper proposes a new method which traces significant element of 2-dimensional natural images and encrypts them by using Fresnelet transform (FRNLT). After analyzing property of the subbands obtained by the FRNLT, we estimated the information for ciphering 2D images. Considering FRNLT levels, energy of subbands, and visual effect, we estimated the optimized point for encryption. By selecting various levels and encrypting region, we can encrypt 2D image with various robustness. Encryption effectiveness was showed by analyzing numerical result, executing time for encryption, area of encrypted region, and visual observation. Therefore encryption for various application can be applied by using the suggested parameters without additional analysis. Identifying the experimental result, in the case of $L_{TH}=4$ and $L_{TH}=4$, an image was not recognized through encrypting only 0.42% among the entire data.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.2 s.302
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• pp.27-36
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• 2005

This thesis proposed an effective encryption method for the DCT-based image/video contents and made it possible to operate in a high speed by implementing it as an optimized hardware. By considering the increase in the amount of the calculation in the image/video compression, reconstruction and encryption, an partial encryption was performed, in which only the important information (DC and DPCM coefficients) were selected as the data to be encrypted. As the result, the encryption cost decreased when all the original image was encrypted. As the encryption algorithm one of the multi-mode AES, DES, or SEED can be used. The proposed encryption method was implemented in software to be experimented with TM-5 for about 1,000 test images. From the result, it was verified that to induce the original image from the encrypted one is not possible. At that situation, the decrease in compression ratio was only $1.6\%$. The hardware encryption system implemented in Verilog-HDL was synthesized to find the gate-level circuit in the SynopsysTM design compiler with the Hynix $0.25{\mu}m$ CMOS Phantom-cell library. Timing simulation was performed by Verilog-XL from CadenceTM, which resulted in the stable operation in the frequency above 100MHz. Accordingly, the proposed encryption method and the implemented hardware are expected to be effectively used as a good solution for the end-to-end security which is considered as one of the important problems.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.4
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• pp.9-21
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• 2004

In this paper, we proposed the image hiding method which decreases calculation amount by encrypt partial data using discrete wavelet transform and linear scale quantization which were adopted as the main technique for frequency transform in JPEG2000 standard. Also we used the chaotic system which has smaller calculation amount than other encryption algorithms and then dramatically decreased calculation amount. This method operates encryption process between quantization and entropy coding for preserving compression ratio of images and uses the subband selection method and the random changing method using the chaotic system. For ciphering the quantization index we use a novel image encryption algerian of cyclically shifted in the right or left direction and encrypts two quantization assignment method (Top-down/Reflection code), made change of data less. Also, suggested encryption method to JPEG2000 progressive transmission. The experiments have been performed with the proposed methods implemented in software for about 500 images. consequently, we are sure that the proposed are efficient image encryption methods to acquire the high encryption effect with small amount of encryption. It has been shown that there exits a relation of trade-off between the execution time and the effect of the encryption. It means that the proposed methods can be selectively used according to the application areas. Also, because the proposed methods are performed in the application layer, they are expected to be a good solution for the end-to-end security problem, which is appearing as one of the important problems in the networks with both wired and wireless sections.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6C
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• pp.648-658
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• 2003

As the usage of image/video contents increase, a security problem for the payed image data or the ones requiring confidentiality is raised. This paper proposed an image encryption methodology to hide the image information. The target data of it is the result from quantization in wavelet domain. This method encrypts only part of the image data rather than the whole data of the original image, in which three types of data selection methodologies were involved. First, by using the fact that the wavelet transform decomposes the original image into frequency sub-bands, only some of the frequency sub-bands were included in encryption to make the resulting image unrecognizable. In the data to represent each pixel, only MSBs were taken for encryption. Finally, pixels to be encrypted in a specific sub-band were selected randomly by using LFSR(Linear Feedback Shift Register). Part of the key for encryption was used for the seed value of LFSR and in selecting the parallel output bits of the LFSR for random selection so that the strength of encryption algorithm increased. The experiments have been performed with the proposed methods implemented in software for about 500 images, from which the result showed that only about 1/1000 amount of data to the original image can obtain the encryption effect not to recognize the original image. Consequently, we are sure that the proposed are efficient image encryption methods to acquire the high encryption effect with small amount of encryption. Also, in this paper, several encryption scheme according to the selection of the sub-bands and the number of bits from LFSR outputs for pixel selection have been proposed, and it has been shown that there exits a relation of trade-off between the execution time and the effect of the encryption. It means that the proposed methods can be selectively used according to the application areas. Also, because the proposed methods are performed in the application layer, they are expected to be a good solution for the end-to-end security problem, which is appearing as one of the important problems in the networks with both wired and wireless sections.