Research Project ”Authenticity of Digital Images II”
Outline of the Problem
While in the past, in the presence of the original (mostly a film negative or a slide/reversal film) the evidential value of a photograph had to be doubted only in exceptional cases, in the age of data processing, it is cast into fundamental doubt due to the ease with which digital images can be manipulated. In this situation, the maintenance or reconstruction of the evidential value of photographs requires a maximum joint effort of all interested parties, especially of course, those of the law enforcement authorities.
Commissioned by the BKA, in 1998 the Fraunhofer Institut für Integrierte Schaltungen (Fraunhofer Institute for Integrated Circuits) in Erlangen defined the technical and organisational framework for a digital camera, which was to fulfil the following police requirements:
- increasing the evidential weight of digital images for use in court through the inclusion of additional information onto the image file, clear identification of the photographer and the camera used, recording of other relevant data,
- manipulation-proof storage of image files together with the additional data,
- proof of image integrity for efficient storage of digital image files,
- clear tracing/tracking of necessary and/or helpful image processing actions (format conversion, adjustments to scale, contrast, compression, etc.).
The Institut für Mikroelektronik (Institute for Microelectronics) in Stuttgart was commissioned with building a prototype (digital camera with signature feature based on electronic signatures). As a public-law foundation of the German state of Baden-Württemberg, this institute conducts application-oriented research and receives manufacture commissions in the field of microelectronics.
During the course of developing the prototype, the very rapid changes on the digital photography market proved to be a major challenge. Nowadays just a few months pass between the release of a new camera and its successor model.
A digital camera which is to fulfil the requirements for the "authenticity of digital images" must be modified in its hardware and control software in order to, for example, include a card reader for signature cards. At the same time, the camera's electronics must be protected against unauthorised modifications, and/or manipulation attempts must be detected automatically.
Potential users would not only comprise police authorities but also professional photographers and expert witnesses, for whom proof of origin and traceable integrity checks of the image files are of special importance.
Original or Forgery?
Authenticity check by comparison of hash checksums