Differencing between compressed archives is a common task in file management and synchronization. Applications include source code distribution, application updates, and document synchronization. General purpose binary differencing tools can create and apply patches to compressed archives, but don’t consider the internal structure of the compressed archive or the file lifecycle. Therefore, they miss opportunities to save space based on the archive’s internal structure and metadata. To address the gap, we develop a content-aware, format independent theory for differencing on compressed archives and propose a canonical form and digest for compressed archives. Based on them, we present Donag, a content-aware differencing and patching algorithm that produces smaller patches than general purpose binary differencing tools on versioned archives by exploiting the compressed archives’ internal structure. Donag uses the VCDiff and BSDiff engines internally. We compare Donag’s patches to ones produced by bsdiff, xdelta3, and Delta++ on three classes of compressed archives: open-source code repositories, large and small applications, and office productivity documents (DOCX, XLSX, PPTX). Donag’s patches are typically 10% to 89% smaller than those produced by bsdiff, xdelta3, and Delta++, with reasonable memory overhead and throughput on commodity hardware. In the worst case, Donag’s patches are negligibly larger.

Users and Operating Systems (OSs) have vastly different views of files. OSs use files to persist data and structured information. To accomplish this, OSs treat files as named collections of bytes managed in hierarchical file systems. Despite their critical role in computing, little attention is paid to the lifecycle of the file, the evolution of file contents, or the evolution of file metadata. In contrast, users have rich mental models of files: they group files into projects, send data repositories to others, work on documents over time, and stash them aside for future use. Current OSs and Revision Control Systems ignore such mental models, persisting a selective, manually designated history of revisions. Preserving the mental model allows applications to better match how users view their files, making file processing and archiving tools more effective. We propose two mechanisms that OSs can adopt to better preserve the mental model: File Lifecycle Events (FLEs) that record a file’s progression and Complex File Events (CFEs) that combine them into meaningful patterns. We present the Complex File Events Engine (CoFEE), which uses file system monitoring and an extensible rulebase (Drools) to detect FLEs and convert them into complex ones. CFEs are persisted in NoSQL stores for later querying.

There is a growing interest in establishing rules to regulate the privacy of citizens in the treatment of sensitive personal data such as medical and financial records. Such rules must be respected by software used in these sectors. The regulatory statements are somewhat informal and must be interpreted carefully in the software interface to private data. This paper describes techniques to formalize regulatory privacy rules and how to exploit this formalization to analyze the rules automatically. Our formalism, which we call privacy APIs, is an extension of access control matrix operations to include (1) operations for notification and logging and (2) constructs that ease the mapping between legal and formal language. We validate the expressive power of privacy APIs by encoding the 2000 and 2003 HIPAA consent rules in our system. This formalization is then encoded into Promela and we validate the usefulness of the formalism by using the SPIN model checker to verify properties that distinguish the two versions of HIPAA

Web services offer an opportunity to redesign a variety of older systems to exploit the advantages of a flexible, extensible, secure set of standards. In this paper we explore the objective of improving Internet messaging (email) by redesigning it as a family of Web services, an approach we call WSEmail. We illustrate an architecture and describe some applications. Since increased flexibility often mitigates against security and performance, we focus on steps for proving security properties and measuring the performance of our system with its security operations. In particular, we demonstrate an automated proof using TulaFale and ProVerif of a correspondence theorem for an application called on-demand attachments. We also provide performance measures for the basic WSEmail functions in a prototype we have implemented using .NET. Our experiments show a latency of about a quarter of a second per transaction under load.