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Modern websites are powered by JavaScript, a flexible dynamic scripting language that executes in client browsers. A common paradigm in such websites is to include third-party JavaScript code in the form of libraries or advertisements. If this code were malicious, it could read sensitive information from the page or write to the location bar, thus(More)
Proving software free of security bugs is hard. Languages that ensure that programs correctly enforce their security policies would help, but, to date, no security-typed language has the ability to verify the enforcement of the kinds of policies used in practice—dynamic, stateful policies which address a range of concerns including forms of access control(More)
Programs written in dynamic languages make heavy use of features --- run-time type tests, value-indexed dictionaries, polymorphism, and higher-order functions --- that are beyond the reach of type systems that employ either purely syntactic or purely semantic reasoning. We present a core calculus, System D, that merges these two modes of reasoning into a(More)
Dataflow analyses for concurrent programs differ from their single-threaded counterparts in that they must account for shared memory locations being overwritten by concurrent threads. Existing dataflow analysis techniques for concurrent programs typically fall at either end of a spectrum: at one end, the analysis conservatively kills facts about all data(More)
A number of programming languages use rich type systems to verify security properties of code. Some of these languages are meant for source programming, but programs written in these languages are compiled without explicit security proofs, limiting their utility in settings where proofs are necessary, e.g., proof-carrying authorization. Others languages do(More)
Direct manipulation interfaces and programmatic systems have distinct and complementary strengths. The former provide intuitive, immediate visual feedback and enable rapid prototyping, whereas the latter enable complex, reusable abstractions. Unfortunately, existing systems typically force users into just one of these two interaction modes. We present a(More)