• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.1
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• pp.3-10
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• 2012

In this paper, we propose a fault injection attack on stream cipher A5/3 used in GSM. The fault assumption of this attack is based on that of fault injection attacks proposed in FDTC'05 and CISC-W'10. This attack is applicable to A5/3 supporting 64/128-bit session key, respectively, and can recover the session key by using a small number of fault injections. These works are the first known key recovery attack results on A5/3.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.6
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• pp.45-54
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• 2011

Corporations use e-mail as their primary method for internal communication and business processes. By their nature, the e-mails are in general used for major business processes that contain large amounts of business information. When there is a critical event, such as Technology leakage, an e-mail message can become important evidence. However, as there is a high likelihood that a suspect will intentionally erase an e-mail message, the ability to recover deleted e-mail is very important. This pater analyzes the deleted e-mail item structure in files of various e-mail clients, and explains the possibility and methods of recovery.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.55-63
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• 2016

SOA(service oriented architecture) based ESB(enterprise service bus) model is widely adopted in many companies for the safe processing of enormous data and the integration of business system. The existing web service technologies for the construction of SOA, however, show unsatisfactory in practical applications though the standardization of web service security technologies is in progress due to their limitations in safe exchange of data. Internal end users using a large business system based on such environment are composed of the variety of organizations and roles. Companies might receive more serious damage from insider threat than that from external one when internal end users get unauthorized information beyond the limits of their authority for private profit and bad purposes. In this paper, we propose a security architecture capable of identifying and coping with the security threats of web service technologies arouse from internal end users.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.2
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• pp.223-230
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• 2013

Recently, a large number of corporations are adopting cloud solution in order to reduce IT-related costs. By the way, Digital Trace should have admissibility to be accepted as digital evidence in court, and integrity is one of the factors for admissibility. In this context, this research implemented integrity verification test to VM Data which was collected by well-known private cloud solutions such as Citrix, VMware, and MS Hyper-V. This paper suggests the effective way to verify integrity of VM data collected in private cloud computing environment based on the experiment and introduces the error that EnCase fails to mount VHD (Virtual Hard Disk) files properly.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.2
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• pp.203-212
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• 2013

Recently, cloud computing is one of the parts showing the biggest growth in the IT market and is expected to continue to grow into. Especially, many companies are adopting virtual desktop infrastructure as private cloud computing to achieve in saving the cost and enhancing the efficiency of the servers. However, current digital forensic investigation methodology of cloud computing is not systematized scientifically and technically. To do this, depending on the type of each cloud computing services, digital evidence collection system for the legal enforcement should be established. In this paper, we focus on virtual desktop infrastructure as private cloud computing and introduce the most widely used around the world desktop virtualization solutions of VMware, Citrix, and Microsoft. And We propose digital forensic investigation methodology for private cloud computing that is constructed by these solutions.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.6
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• pp.1157-1167
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• 2013

The development of electronic devices has recently led to many problems such as personal information rape and leakage of business information. Conventional loud-speakers have been generally used to output devices. It can be, however, operated as a micro-phone which was abused as a means for eavesdropping since the speaker and microphone have basically the equivalent structure. Most importantly, the general peoples are not aware of the approaching danger about using speaker as microphone. And, traditional eavesdropping detection equipment does not check the attack. In this paper, we demonstrate that there is a serious danger and vulnerability in using loud-speakers since they can be used as eavesdropping devices.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.3
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• pp.631-643
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• 2016

Currently, General Number Field Sieve(GNFS) is known as the most efficient way for factoring large numbers. CADO-NFS is an open software based on GNFS, that was used to factor RSA-704. Polynomial selection in CADO-NFS can be divided into two stages - polynomial selection, and optimization of selected polynomial. However, optimization of selected polynomial in CADO-NFS is an immense procedure which takes 90% of time in total polynomial selection. In this paper, we introduce modification of optimization stage in CADO-NFS. We implemented precomputation table and modified optimization algorithm to reduce redundant calculation for faster optimization. As a result, we select same polynomial as CADO-NFS, with approximately 40% decrease in time.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.2
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• pp.345-352
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• 2014

As the utilization rate of smart device increases, various applications for smart device have been developed. Since these applications can contain important data related to user behaviors in digital forensic perspective, the analysis of them should be conducted in advance. However, lots of applications get to have new data format or type when they are updated. Therefore, whether the applications are updated or not should be checked one by one, and if they are, whether their data are changed should be also analyzed. But observing application data repeatedly is a time-consuming task, and that is why the effective method for dealing with this problem is needed. This paper suggests the automatic system which gets updated information and checks changed data by collecting application information.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.1
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• pp.53-62
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• 2009

H. Gilbert et al. proposed a collision attack on 7-round reduced Rijndael[5]. Applying this attack, we propose collision attacks on 8-round reduced Crypton, 8-round reduced mCrypton in this paper. Attacks on Crypton requires $2^{161.6}$ time complexity with $2^{96}$ chosen plaintexts, respectively. The attack on mCrypton requires $2^{81.6}$ time complexity with $2^{48}$ chosen plaintexts. These results are the best attacks on Crypton and mCrypton in published literatures.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.4
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• pp.3-12
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• 2006

RFID (Radio Frequency Identification) system is expected to play a critical role providing widespread services in the ubiquitous period. However, widespread use of RFID tags may create new threats to the privacy of individuals such as information leakage and traceability. It is difficult to solve the privacy problems because a tag has the limited computing power that is not the adequate resource to support the general encryption. Although the scheme of [2] protects the consumer privacy using an external agent, a tag should compute exponential operation needed high cost. We propose Self Re-Encryption Protocol (SREP) which provides song privacy without assisting of any external agent. Our SREP is well suitable to low-cost RFID system since it only needs multiplication and exclusive-or operation.