Effects of Motivation and Demography on the Quantitative Plausibility of the Trojan Horse Defence Against Possession of Child Pornography

Richard E Overill¹, Jantje A M Silomon¹, Kam-Pui Chow² , Hayson Tse²

(1. Dept. of Informatics, King’s College London, London WC2R 2LS, United Kingdom; 2. Dept. of Computer Science, University of Hong Kong, Hong Kong, China)



Abstract:

The Enhanced Complexity Model (ECM) developed previously has been further extended to produce a Motivationally Enhanced Complexity Model (MECM) which enables the degree of motivation, capability and opportunity of a hypothetical Trojan Horse author to be included in quantifying the relative plausibility of competing explanations for the existence of uncontested digital evidence. This new model has been applied to the case of the Trojan Horse defence (THD) against the possession of child pornography. Our results demonstrate that the THD in this case cannot be plausibly sustained unless it can be shown that an ‘off-the-shelf’ (OTS) Trojan Horse for this task is available and it is not detectable by the target computer, at the material time.

Key words:  Trojan Horse defence  child pornography  digital forensic evidence  complexity  quantitative plausibility metrics  posterior odds

DOI：10.11916/j.issn.1005-9113.2014.06.003

Clc Number:TP39

Fund: