Alan B. Shaffer

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Covert channels can result in unauthorized information flows when exploited by malicious software. To address this problem, we present a precise, formal definition for covert channels, which relies on control flow dependency tracing through program execution, and extends Dennings' and subsequent classic work in secure information flow [9][40][30]. A formal(More)
Evaluation of high assurance secure computer systems requires that they be designed, developed, verified and tested using rigorous processes and formal methods. The evaluation process must include correspondence between security policy objectives, security specifications, and program implementation. This research presents an approach to the verification of(More)
Unauthorized information flows can result from malicious software exploiting covert channels and overt flaws in access control design. To address this problem, we present a precise, formal definition for information flow that relies on control flow dependency tracing through program execution, and extends Dennings' and follow-on classic work in secure(More)
Within a multilevel secure (MLS) system, trusted subjects are granted privileges to perform operations that are not possible by ordinary subjects controlled by mandatory access control (MAC) policy enforcement mechanisms. These subjects are trusted not to conduct malicious activity or degrade system security. We present a formal definition for trusted(More)
BACKGROUND Standardized training and clinical protocols using biofeedback for the treatment of fecal incontinence (FI) are important for clinical care. Our primary aims were to develop, implement, and evaluate adherence to a standardized protocol for manometric biofeedback to treat FI. METHODS In a Pelvic Floor Disorders Network (PFDN) trial, participants(More)
Approved for public release; distribution is unlimited. Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instruction, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments(More)
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