Abstract

The results of an experiment that shows that it is very simple to contaminate digital images with information that can later be extracted are presented. This contamination cannot be detected when the image is displayed on a good quality graphics workstation. Based on these results, it is recommended that image downgrading based on visual display of the image to be downgraded not be performed if there is any threat of image contamination by Trojan horse programs. Potential Trojan horse programs may include untrusted image processing software. 1 Introduction For as long as there has been classified information, there has been a need to de-classify or downgrade information that has been classified above its currently appropriate level. On some occasions, wholesale reclassification is permitted, as in the case of automatic downgrading of an entire document after some predetermined time period has elapsed. In other cases, piecemeal downgrading is done, using a combination of cutting and pa...

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