• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2153-2158
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• 2016

Multimedia such as image, audio, and video is easy to create and distribute with the advance of IT. Since novice uses them for illegal purposes, multimedia forensics are required to protect contents and block illegal usage. This paper presents a multimedia forensic algorithm for video to identify the device used for acquiring unknown video files. First, the way to calculate a sensor pattern noise using Wiener filter (W-SPN) is presented, which comes from the imperfection of photon detectors against light. Then, the way to identify the device is explained after estimating W-SPNs from the reference device and the unknown video. For the experiment, 30 devices including DSLR, compact camera, smartphone, and camcorder are tested and analyzed quantitatively. Based on the results, the presented algorithm can achieve the 96.0% identification accuracy.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.8
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• pp.3943-3957
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• 2016

As digital evidence has a highly influential role in proving the innocence of suspects, methods for integrity verification of such digital evidence have become essential in the digital forensic field. Most surveillance camera systems are not equipped with proper built-in integrity protection functions. Because digital forgery techniques are becoming increasingly sophisticated, manually determining whether digital content has been falsified is becoming extremely difficult for investigators. Hence, systematic approaches to forensic integrity verification are essential for ascertaining truth or falsehood. We propose an integrity determination method that utilizes the structure of the video content in a Video Event Data Recorder (VEDR). The proposed method identifies the difference in frame index fields between a forged file and an original file. Experiments conducted using real VEDRs in the market and video files forged by a video editing tool demonstrate that the proposed integrity verification scheme can detect broken integrity in video content.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.4
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• pp.647-659
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• 2023

As digital evidence becomes more important in criminal investigations, disputes are increasing in court. As media diversifies and the scope of analysis expands, the level of expertise in digital forensics is also increasing. However, no competency model has been developed to define the capabilities of digital evidence examiners or to judge their expertise. There have been some studies that have derived the capabilities necessary for digital evidence examiner, but they are still insufficient. Therefore, in this study, 25 competency evaluation factors in a total of 9 competency groups were defined using methodologies such as expert FGI and Delphi survey. Specifically, it was defined as Digital Forensics Theory, Digital Evidence Collection&Management, Disk Forensics, Mobile Forensics, Video Forensics, infringement forensics, DB Forensics, Embedded(IoT) Forensics, and Cloud Forensics. The digital evidence examiner competency model is expected to be used in various fields such as recruitment, education and training, and performance evaluation in the future.

• Journal of Digital Forensics
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• v.12 no.3
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• pp.71-82
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• 2018

Using small cameras such as smartphones, criminals shoot secretly in public restrooms and women's changing rooms. And Revenge porn is also increasing. As a result social damage is increasing. Tumblr is an overseas service and it is very difficult to work with Tumbler on international legal cooperation and deletions. Thus In order to block the distribution of videos, victims must find and report the video URL themselves. But it's hard for victims who lack IT expertise to proceed those procedure. In this study, we automatically collect the URL of stored information and hash values of the images from API permlink of Tumbler blog. It is then saved as a document file with and presented to the victim. Through these technical methods, we can help victims report violations easily and quickly.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.2
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• pp.323-331
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• 2013

There are three ways how to extract forensic evidence from mobile phone, such as SYN, JTAG, Revolving. However, it should be a different way to extract forensic evidence due to the differences of their usage and technology between them(mobile phone and smart phone). Therefore, in this paper, I will come up with extraction method that forensics evidence by search and seizure of a smart phone. This study aims to analyze specifications and O.S., backup analysis, evidence in smart to analyze for search and seizure of a smart phone commonly used google android and windows mobile smart phone. This study also aim to extract forensics evidence related to google android and phone book, SMS, photos, video of window mobile smart phone to make legal evidence and forensics report. It is expected that this study on smart phone forensics technology will contribute to developing mobile forensics technology.

• Journal of the Korea Society of Computer and Information
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• v.22 no.6
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• pp.41-48
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• 2017

All the personal information controllers or processors collecting, processing and storing personal information through the entry into force of the EU GDPR (General Data Protection Regulation) are required to provide the basic principle of privacy by design at all stages of developing products or services throughout the organization, And to ensure that the basic rights of the subject of personal information are protected and that internal control techniques are provided to prevent any abuse or leakage. We will review the regulations and countermeasures required by the GDPR for video information with serious privacy problems, and propose a solution.

• Journal of Digital Forensics
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• v.12 no.3
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• pp.1-8
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• 2018

A random chat application is a type of social dating application that helps people find a lover or spouse by randomly connecting and providing services such as text, voice and video chat. Recently, there has been globally a rapid increase in its use due to the fact that it provides people to quick and convenient encounters at low cost. However, it is used as one of method to prostitute or to trade drugs and become a cause of violent crimes due to various criminal occurring after actual meeting between app users. For this reason, a random chat application is likely to provide proof of prostitution or drug trade and clues to arrest rape, kidnapping and murder suspects. Thus, it is necessary to analyse random chat applications from the viewpoint of digital forensics investigation, but there is no related research at all. Therefore, in this paper, we analyzed artifacts of 6 Korea random chat application's user behaviors; Ranchat, AngTalk, SsumgThing, DaTalk, EveryTalk and Sail. As a result, we found that it is remain on mobile device that time and contents of message transmission/reception, sender/receiver, friend profile and user account creation time when user is using the applications.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.1
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• pp.15-22
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• 2017

With the advance of Internet Technology, various social network services are created and used by users. Especially, the use of smart devices makes that multimedia contents can be used and distributed on social network services. However, since the crime rate also is increased by users with illegal purposes, there are needs to protect contents and block illegal usage of contents with multimedia forensics. In this paper, we propose a multimedia forensic technique which is identifying the video source. First, the scheme to acquire the sensor pattern noise (SPN) using morphology filtering is presented, which comes from the imperfection of photon detector. Using this scheme, the SPN of reference videos from the reference device is estimated and the SPN of an unknown video is estimated. Then, the similarity between two SPNs is measured to identify whether the unknown video is acquired using the reference device. For the performance analysis of the proposed technique, 30 devices including DSLR camera, compact camera, camcorder, action cam and smart phone are tested and quantitatively analyzed. Based on the results, the proposed technique can achieve the 96% accuracy in identification.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.463-466
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• 2012

Smartphones along with the development of crime evidence has been using smartphones. Phone's internal storage medium can be used as evidence in the case of images, video, phone, GPS information, there are Internet access and other data records. Therefore, these data to collect evidence of a systematic procedure for collecting and analyzing evidence is needed. In this paper, the target mobile phone forensics forensic evidence collection, evidence analysis, and reporting results to the procedures and how to draw. Through this paper, phone forensics and will serve as a basis for the investigation.

• Journal of Broadcast Engineering
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• v.22 no.6
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• pp.734-743
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• 2017

In this paper, we introduce a technique to detect the video forgery using coding pattern analysis. In the proposed method, the recently developed standard HEVC codec, which is expected to be widely used in the future, is used. First, HEVC coding patterns of the forged and the original videos are analyzed to select the discriminative features, and the selected feature vectors are learned through the machine learning technique to model the classification criteria between two groups. Experimental results show that the proposed method is more effective to detect frame deletions for HEVC-coded videos than existing works.