• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.5
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• pp.153-164
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• 2004

Under a large-scale client-server service environment, e.g., online games, encrypting data for acquiring information security often causes overload to the server and hence degradation of the service itself. Therefore, for reducing encryption payload, it is necessary to use adequately an efficient encryption scheme with respect to the security requirements of transmission data. In this paper, we propose a packet encryption scheme using multiple cryptosystems to realize such capability, which assigns a different cryptosystem according to the security requirements level. The proposed encryption scheme is applicable to internet services with heavy traffic ratios in which different kinds of data packets are incessantly transmitted between clients and servers. To show its effectiveness and superiority, the performance of the proposed encryption scheme is verified by experiments.

• Review of KIISC
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• v.17 no.2
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• pp.9-23
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• 2007

The air interface supports a security layer which provides the key exchange protocol, authentication protocol, and encryption protocol. The authentication is performed on the encryption protocol packet. The authentication protocol header or trailer may contain the digital signature that is used to authenticate a portion of the authentication protocol packet that is authenticated. The encryption protocol may add a trailer to hide the actual length of the plaintext of padding to be used by the encryption algorithm. The encryption protocol header may contain variables such as the initialization vector (IV) to be used by the encryption protocol. It is our aim to firstly compute the session key created from the D H key exchange algorithm, and thereof the authenticating key and the encryption key being generated from the session key.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.2
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• pp.83-92
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• 2007

In connectionless packet network, if a sender encrypts packets by block chaining mode and send it to receiver, the receiver should decrypt packets in encrypted order that is not received order. Therefore, the performance and efficiency are lowered for crypto communication system. To solve this problem, we propose packet encryption scheme for connectionless packet network that can decrypt the packets independently, even if the received order of packets are changed or packets are missed. The scheme makes new IV(Initial Vector) using IV that created by key exchange process and salt that made by random number. We propose extended Cryptoki API that added packet encryption/decryption functions and mechanism for improving convenience and performance. We implement the scheme and get result that the performance increased about $1.5{\sim}l5.6$ times compare with in case of implementing using Cryptoki API in the test environment.

• 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.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2750-2752
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• 2001

각종 행정 업무나 금융 업무 등 많은 분야의 업무를 Network로 처리할 수 있도록 Internet 환경이 구축된 현실에서 개개인의 신상정보 또는 금융정보 등과 같은 누설되어서는 안 되는 다량의 정보들이 Internet을 통해 전송 되어지고 있다. 거미줄처럼 얽혀있는 Internet망을 통한 통신 중 어디 한곳에서라도 정보가 손실된다면 큰 혼란을 가져 올 것이다. 또한 누군가가 Internet망을 통해 전송되는 정보들을 들여다 볼 수 있다면 Encryption되지 않은 Data는 모두 누설되고 말 것이다. 이러한 위험요소들은 기술적으로 구현이 가능하며 실제적으로도 암암리에 행해지고 있는 것으로 알려져 있다. 현재 Internet Security를 위한 많은 Encryption Protocol이 존재하고 있지만 일관된 Encryption Protocol의 부재, 사용의 어려움, Cryptography Application의 부재로 인하여 Encryption을 사용할 수 없는 경우가 많이 있다. 본 논문에는 Eavesdropping의 원리를 이해하고 이에 대한 대책을 제시하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.841-847
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• 2015

The WAVE(Wireless Access in Vehicular Environments) communication system supports wireless communication environments between vehicles. As the utilization of wireless communication has been increased, attack methods have been varied. There is a high risk on packet manipulations conducted by third party. In this paper, we have designed a secure communication protocol between CA and vehicles. Our designed protocol uses a ECIES(Elliptic Curve Integrated Encryption Scheme) for vehicle authentication and AES(Advanced Encryption Standard) algorithm for protecting packet integrity and confidentiality.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.6
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• pp.931-936
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• 2002

By emphasize and enhance security in encryption of same viewdata in this research, constructed video conference system that apply real time video encryption techniques that confidentiality and integrity aspect are emphasized than video conference system that depend on existent user certification techniques. Sender's image transmits Vernam's encryption process to listener by packet. Listener can display image through image's decipher process and uncompress after unite receiving transmited image. This time, solved transmission speed delay problem by video's real time encryption using Vernam's algorithm that encryption and the decipher speed are fast. Simplification problem of Vernam algorithm wished to solve Session Key that use security Key that is used encipherment and decipher in channel between Client and Server using RSA algorithm.

• International Journal of Internet, Broadcasting and Communication
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• v.11 no.3
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• pp.59-63
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• 2019

VoIP technology is a technology for exchanging voice or video data through IP network. Various protocols are used for this technique, in particular, RTP(Real-time Transport Protocol) protocol is used to exchange voice data. In recent years, with the development of communication technology, there has been an increasing tendency of services such as "Kakao Voice Talk" to exchange voice and video data through IP network. Most of these services provide a service with security guarantee by a user authentication process and an encryption process. However, RTP protocol does not require encryption when transmitting data. Therefore, there is an exposition risk in the voice data using RTP protocol. We will present the risk of the situation where packets are sniffed in VoIP(Voice over IP) communication using RTP protocol. To this end, we configured a VoIP telephone network, applied our own sniffing tool, and analyzed the sniffed packets to show the risk that users' data could be exposed unprotected.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.274-277
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• 2008

Rekeying is the process of changing the encryption key of an ongoing communication. The main objective is to limit the amount of data encrypted with the same key. The IEEE 802.11 standard defines the Wired Equivalent Privacy, or WEP, encapsulation of 802.11 data frames. MAC at sender encrypts the payload (frame body and CRC) of each 802.11 frame before transmission using RC4 stream cipher. MAC at receiver decrypts and passes data to higher level protocol. WEP uses symmetric key stream cipher (RC4) where same key will be used for data encryption and decryption at the sender and the receiver. WEP is not promising with the advancement of the wireless technology existing today. We propose to use the existing information to define the security attributes. This will eliminate the steps that regenerated keys have to be sent to each other over certain period. The rekeying scheme is according to the number of bytes transmitted. Therefore, even the attacker has recorded the packets, it will be insufficient information and time for the attacker to launch the attacks as the key is not deterministic. We develop a packet simulation software for packet transmission and simulate our propose scheme. From the simulation, our propose scheme will overcome the weak WEP key attack and provide an alternative solution to wireless packet transmission. Besides that, our solution appears to be a software approach where only driver updates are needed for the wireless client and server.

• 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.