• Journal of Internet of Things and Convergence
• /
• v.9 no.6
• /
• pp.23-28
• /
• 2023

Windows operating system generates various logs with timestamps. Timestamp tampering is an act of anti-forensics in which a suspect manipulates the timestamps of data related to a crime to conceal traces, making it difficult for analysts to reconstruct the situation of the incident. This can delay investigations or lead to the failure of obtaining crucial digital evidence. Therefore, various techniques have been developed to detect timestamp tampering. However, there is a limitation in detection if a suspect is aware of timestamp patterns and manipulates timestamps skillfully or alters system artifacts used in timestamp tampering detection. In this paper, a method is designed to detect changes in timestamps, even if a suspect alters the timestamp of a file on a storage device, it is challenging to do so with precision beyond millisecond order. In the proposed detection method, the first step involves verifying the timestamp of a file suspected of tampering to determine its write time. Subsequently, the confirmed time is compared with the file size recorded within that time, taking into consideration the performance of the storage device. Finally, the total capacity of files written at a specific time is calculated, and this is compared with the maximum input and output performance of the storage device to detect any potential file tampering.

• KIPS Transactions on Computer and Communication Systems
• /
• v.5 no.7
• /
• pp.173-180
• /
• 2016

Since smartphones possess a variety of user information, we can derive useful data related to the case from app data analysis in the digital forensic perspective. However, it requires an appropriate forensic measure as smartphone has the property of high mobility and high possibility of data loss, forgery, and modulation. Especially the forged/modulated time-stamp impairs the credibility of digital proof and results in the perplexity during the timeline analysis. This paper provides traces of usage which could investigate whether the time-stamp has been forged/modulated or not within the range of iOS based devices.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2019.07a
• /
• pp.391-392
• /
• 2019

본 논문에서는 타임스탬프의 위변조를 위한 안티포렌식의 도구로 사용되는 타임스탬프 변경도구들에 기능에 대하여 디지털 포렌식 관점에서 분석을 수행한다. 타임스탬프 변경도구들로써 수행할 수 있는 타임스탬프 변경작업의 범위와 특징을 찾아본다. NTFS파일시스템에서 사용하는 타임스탬프 변경도구들의 기능상의 분류는 그것들이 변경할 수 있는 타임스탬프 종류와 정밀도를 기준으로 정하고 그 도구들을 사용한 후에 기록된 타임스탬프의 특징들을 디지털 포렌식 관점에서 분석을 수행하기로 한다. 이 연구에서의 분류 형태 중 타입 I은 FileTouch.exe, SKTimeStamp, BulkFileChanger류의 도구들과 타입 II는 timestomp, 타입 III은 SetMACE로 분류하고 각 도구들을 사용한 후에 변경된 타임스탬프들의 특징을 살펴보기로 한다.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.8
• /
• pp.2179-2187
• /
• 1999

To privide multimedia mobile communication services for the users in scattered locations, the application ATM cells efficiently in wireless communications, it is effective to the use TDMA method. However, it is necessary to have methods to compensate the CDV(cell delay variation) caused by the difference between TDMA-ATM and cell stream multiplexing of the users. This paper optimizes the cell control time(Tc) when VBR traffic inputs have MMPP by applying CDV characteristics of time stamp method, which has the most advantages among compensation methods of CDV. This paper suggests a cell stream multiplex method employing time stamp techniques to reduce CDV for wireless suggest method shows that CDV distribution and cell stream multiples rangd can be controlled to 1.2${\times}$Tc which reduced over the VBR service in the TDMA-WATM transmission. This paper also presents evaluation of the suggested architecture obtained simulation.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
• /
• 2006.06a
• /
• pp.551-554
• /
• 2006

보안 침해사고시 수집된 디지털 증거를 법적 증거로써 제출하기 위해 신뢰성이 확보되어야한다. 이를 위한 디지털 증거 무결성 보증 기법들중 MDC를 사용한 디지털 증거 무결성 보증 기법은 MDC값을 공격자가 위조 변조 할 수 있다는 단점이 있다. 또 PKI를 이용한 공증 방식은 기존의 증거 수집 시스템을 수정해야 하는 단점과 새로 시스템을 도입하기 위한 비용이 많이 드는 단점이 있다. 따라서 본 논문에서 제안하는 디지털 증거 보호 기법은 Diffie-Hellman(DH) 키 교환 알고리즘을 이용하여 생성된 비밀키와 디지털 증거 수집 대상 시스템(Collecotion System-CS)의 하드웨어 정보($HW_{CS}$)로 디지털 증거(D), 디지털 증거에 대한 해쉬값(H(D))과 타임스탬프(Time)를 암호화해서 디지털 증거에 대한 기밀성, 인증 및 무결성을 보증하는 기법을 제안하였다.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
• /
• 2006.06a
• /
• pp.623-626
• /
• 2006

위치 정보 기반 서비스는 휴대 무선 통신 기기 사용의 확대에 따라 서비스의 범위가 크게 확장될 것으로 예상되고 있다. 그러나 단순한 정보 제공이 아닌 원격 제어, 콘텐츠 서비스 등의 경우에서 위치 정보에 대한 위변조 문제와 사용자의 프라이버시 문제가 발생할 것으로 예상된다. 기존의 위치 정보 보호에 대한 연구는 프라이버시 보호 측면을 위주로 하고 있으며, 인증에 대한 연구는 특정 센싱 기술에 특화되어 있거나, 네트워크상의 DNS를 통한 논리적인 위치 인증에 치우치고 있다. 본 연구에서는 위치 정보 기반 서비스에서의 보안 요구 사항을 분석하여, 기존의 위치 정보 보호 모델을 기반으로 위치 정보를 관리하는 신뢰되는 기관의 필요성을 논하며, 이를 토대로 타임스탬프나 키 갱신을 이용하는 두 가지 프로토콜을 제안한다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.4
• /
• pp.43-51
• /
• 2016

Preventing the forgery and alteration of test reports is important, in order to maintain the reliability of military supplies. Based on a survey of reports on testing institutions and a case study of established electronic document systems in the public sector, we propose a system architecture, which helps prevent the forgery and alteration of test reports with legal force. The proposed architecture takes advantage of both the time stamp that records the time a document is received and a server synchronized with the testing institution. Using the proposed system architecture, the user is able to request a test and receive reports from the testing institution without delay. Also, a defense agency is able to conveniently prove the authenticity of the test reports and utilize the statistical data collected by the architecture. Therefore, we expect that the proposed system architecture will help defense agencies to prevent the forgery and alteration of test reports and ensure their reliability and quality.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.10
• /
• pp.4814-4821
• /
• 2012

An e-passport is equipped with bio information by adding the non-attachable IC chip with a smart function. In order to solve such a problem, the user's privacy is protected by using the BAC, PA, AA and EAC mechanisms. However, the password key used in the BAC mechanism is made of the combination of the MRZ values. As a result, it is possible to decode the password by using the indiscriminate attacking program after finding out the combined rules of MRZ. This thesis suggests the mechanism with an improved level of efficiency through the time-stamp values by using the information of images and fingerprints and checking the forge or falsification of the e-passport when establishing a safe channel between the chip of the e-passport and the decoding system.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.12
• /
• pp.5049-5057
• /
• 2010

As communication technologies are developed and variety of services to mobile devices are provided, mobile users is rapidly increasing every year. However, mobile services running on wireless network environment are exposed to various security threats, such as illegal tampering, eavesdropping, and disguising identity. Accordingly, the secure mobile communications services to 3GPP were established that the standard for 3GPP-AKA specified authentication and key agreement. But in the standard, sequence number synchronization problem using false base station attack and privacy problem were discovered through related researches. In this paper, we propose an efficient authentication mechanism for enhanced privacy protection in the 3G network. We solve the sequence number synchronization existing 3GPP authentication scheme using timestamp and strengthen a privacy problem using secret token. In addition, the proposed scheme can improve the bandwidth consumption between serving network and home network and the problem of authentication data overhead for the serving network because it uses only one authentication vector.

• The Transactions of the Korea Information Processing Society
• /
• v.3 no.3
• /
• pp.512-522
• /
• 1996

To provide broadband ISDN service for the users in scattered locations, the application of satellite communications network is seriously considered. To trans mit ATM cells efficiently in satellite communications, it is effective to use TDM A method. However, it is necessary to have a method to compensate the cell delayvari-ation caused by the difference between TDMA and ATM. This paper optimized the cell control time(Tc) when traffic inputs have poisson or markov modulated poisson process by applying cell delay variation characteristics of time stamp method, which has the most advantages among compensation methods or cell delay variation. This paper also intorduces a method of reducing the cell clumping phenomena by adapting discrete time stamp method, including the analysis and evalutation of the range of required quality of CDV distribution by ATM transmission.The result of the experiment shows that CDV distribution-range can be controlled to 1.2$\times$Tc which reduces overall cell delay variation by discrrete time stamp method.