Alan Woodward

Alan Woodward

Lawful exceptional access (EA) systems hold the cryptographic keys that decrypt protected communications for authorised parties. The debate over their risks has been long and qualitative, complicated by two problems: no public dataset of EA-specific compromise events exists, so assessment must use sparse, indirect evidence; and prior work has treated structurally different designs as equivalent, though transmission-layer EA in carrier infrastructure (T-EA) and over-the-top EA at the platform layer (OTT-EA) differ in how cryptographic keys relate to ciphertext data. This paper builds a structured uncertainty framework for evaluating systemic compromise risk in EA architectures. It does not produce predictive forecasts, which the evidence cannot support; it separates findings robust to assumptions from those that depend on calibration. Four analytical layers are applied to T-EA and OTT-EA: three empirical pillars (historical analogues, a Monte Carlo scenario layer, a channel-independence decomposition) plus a Bayesian Structural Risk Model on a parallel-subgraph attack graph. The central findings are structural. First, EA-equipped architectures of either class carry strictly higher modelled risk than their no-EA counterfactual, an ordering independent of calibration. Second, the classes differ in distribution shape: T-EA risk is dominated by central tendency, OTT-EA by the tail under correlated campaigns. Third, calibration-conditional annual probability ranges span 1.4% to 12.9% for T-EA across the structured-judgement targeting-premium interval. Over multi-decade horizons, cumulative compromise is well above zero; key-material exfiltration is irreversible, weighing heavily on OTT-EA's larger user populations. The framework quantifies compromise probability, not expected harm; consequence modelling and benefit estimation are outside its scope.

K. Cabaj, L. Caviglione, W. Mazurczyk et al.

Compared to cryptography, steganography is a less discussed domain. However, there is a recent trend of exploiting various information hiding techniques to empower malware, for instance to bypass security frameworks of mobile devices or to exfiltrate sensitive data. This is mostly due to the need to counteract increasingly sophisticated security mechanisms, such as code analysis, runtime countermeasures, or real-time traffic inspection tools. In this perspective, this paper presents malware exploiting information hiding in a broad sense, i.e., it does not focus on classical covert channels, but also discusses other camouflage techniques. Differently from other works, this paper solely focuses on real-world threats observed in the 2011 - 2017 timeframe. The observation indicates a growing number of malware equipped with some form of data hiding capabilities and a lack of effective and universal countermeasures.