NCJ Number
222501
Date Published
April 2008
Length
7 pages
Annotation
This paper discusses specific methods and provides examples of these methods in maintaining the integrity of digital media files.
Abstract
When working with digital image and digital video files, the integrity of the files must be maintained and it must also be demonstrated that the steps taken were effective. Maintaining integrity requires security of files during transport and storage. Demonstrating integrity uses methods to show that the file has not changed. Some common methods for maintaining integrity include: written documentation, physical security/environment, redundant physical copies, logical security (WAN/LAN), and third-party escrowing. Some common methods for demonstrating integrity include: hashing function, visual verification, digital signature, written documentation, checksums/cyclical redundancy check (CRC), encryption, watermarks, and proprietary methods. Three specific work-flow examples presented on best practices in maintaining the integrity of digital media include: (1) a series of digital pictures taken at a scene and visually verified on the camera; (2) a series of digital still pictures taken using multiple flash cards at a scene and visually verified in the camera; and (3) in the course of an investigation, a digital video camera is seized. The mini DV tape is removed, and the write-protection tab is engaged. The integrity of a digital image or video file is best demonstrated through a combination of methods. This paper covers these methods and provides examples of best practices utilizing these methods for maintaining and demonstrating integrity of digital media. Figures and a list of suggested readings