Color-decoupled photo response non-uniformity for digital image forensics

The last few years have seen the use of photo response non-uniformity noise (PRNU), a unique fingerprint of imaging sensors, in various digital forensic applications such as source device identification, content integrity verification and authentication. However, the use of a colour filter array for capturing only one of the three colour components per pixel introduces colour interpolation noise, while the existing methods for extracting PRNU provide no effective means for addressing this issue. Because the artificial colours obtained through the colour interpolation process is not directly acquired from the scene by physical hardware, we expect that the PRNU extracted from the physical components, which are free from interpolation noise, should be more reliable than that from the artificial channels, which carry interpolation noise. Based on this assumption we propose a Couple-Decoupled PRNU (CD-PRNU) extraction method, which first decomposes each colour channel into 4 sub-images and then extracts the PRNU noise from each sub-image. The PRNU noise patterns of the sub-images are then assembled to get the CD-PRNU. This new method can prevent the interpolation noise from propagating into the physical components, thus improving the accuracy of device identification and image content integrity verification

A Policy Examination of Digital Multimedia Evidence in Police Department Standard Operating Procedures (SOPs)

2020 will be a year forever marked by the Covid-19 pandemic. The year will also be remembered for the death of George Floyd at the hands of police officer Derek Chauvin. The death was recorded by a bystander’s cell phone and broadcast all over the world to see. This video proved pivotal in the prosecution and conviction of Chauvin for Floyd’s death. The video provided powerful evidence highlighting the importance of incorporating video evidence into the investigation and prosecution of crime. Today, police use a variety of video evidence to assist in their investigations. In some cases, it may be a small part of the case whereas in others it may provide vital evidence. There has been an explosion in the number of video sources where police can now gather evidence. Cellphone videos, private security cameras on homes or businesses, social media postings, and police body cameras all provide possible evidence that must be collected, extracted and analyzed. In 2019, there were 40 million professionally installed video recording systems and 224 million smartphones in the U.S. alone. Along with the approximately 400,000 body cameras worldwide, there is a numerous amount of video available to investigators. It is important for police departments to acquire this video evidence according to legal requirements and best practices according to industry leaders to avoid any future legal challenges to the evidence. This study will analyze how police departments around the country are handling video evidence through their Standing Operating Procedures (SOPs) using legal requirements and industry best practices as a guideline. The author chose to concentrate on two of the main legal challenges facing law enforcement today while working with digital evidence: authentication and integrity. Despite sometimes being used interchangeably, authentication and integrity present two different challenges when working with digital evidence. Authentication is when the evidence put forth in a trial is what the party admitting it into evidence claims it to be. Integrity is ensuring the evidence has not been changed or altered since its original form. In this study, the author chose to concentrate on the issues of authentication and integrity specifically in relation to Digital Multimedia Evidence (DME). DME is information of probative value stored in binary form including but not limited to tape, film, magnetic, optical media, and/or the information contained therein. The author created a rubric utilizing best practices identified by industry leaders along with legal guidelines set forth by the Federal Rules of Evidence, court cases, and law reviews. The rubric evaluated the Department’s SOPs on three phases: Training, Process, and Documentation

Rethinking Digital Forensics

© IAER 2019In the modern socially-driven, knowledge-based virtual computing environment in which organisations are operating, the current digital forensics tools and practices can no longer meet the need for scientific rigour. There has been an exponential increase in the complexity of the networks with the rise of the Internet of Things, cloud technologies and fog computing altering business operations and models. Adding to the problem are the increased capacity of storage devices and the increased diversity of devices that are attached to networks, operating autonomously. We argue that the laws and standards that have been written, the processes, procedures and tools that are in common use are increasingly not capable of ensuring the requirement for scientific integrity. This paper looks at a number of issues with current practice and discusses measures that can be taken to improve the potential of achieving scientific rigour for digital forensics in the current and developing landscapePeer reviewe