Trace Oblivious Program Execution

The big data era has dramatically transformed our lives; however, security incidents such as data breaches can put sensitive data (e.g. photos, identities, genomes) at risk. To protect users' data privacy, there is a growing interest in building secure cloud computing systems, which keep sensitive data inputs hidden, even from computation providers. Conceptually, secure cloud computing systems leverage cryptographic techniques (e.g., secure multiparty computation) and trusted hardware (e.g. secure processors) to instantiate a “secure” abstract machine consisting of a CPU and encrypted memory, so that an adversary cannot learn information through either the computation within the CPU or the data in the memory. Unfortunately, evidence has shown that side channels (e.g. memory accesses, timing, and termination) in such a “secure” abstract machine may potentially leak highly sensitive information, including cryptographic keys that form the root of trust for the secure systems. This thesis broadly expands the investigation of a research direction called trace oblivious computation, where programming language techniques are employed to prevent side channel information leakage. We demonstrate the feasibility of trace oblivious computation, by formalizing and building several systems, including GhostRider, which is a hardware-software co-design to provide a hardware-based trace oblivious computing solution, SCVM, which is an automatic RAM-model secure computation system, and ObliVM, which is a programming framework to facilitate programmers to develop applications. All of these systems enjoy formal security guarantees while demonstrating a better performance than prior systems, by one to several orders of magnitude.

READY FOR KINDERGARTEN: A TRAINING PROGRAM DESIGNED TO ENCOURAGE PARENT-CHILD CONVERSATION DURING THE PRESCHOOL YEARS

Many children in the United States begin kindergarten unprepared to converse in the academic language surrounding instruction, putting them at greater risk for later language and reading difficulties. Importantly, correlational research has shown there are certain experiences prior to kindergarten that foster the oral language skills needed to understand and produce academic language. The focus of this dissertation was on increasing one of these experiences: parent-child conversations about abstract and non-present concepts, known as decontextualized language (DL). Decontextualized language involves talking about non-present concepts such as events that happened in the past or future, or abstract discussions such as providing explanations or defining unknown words. As caregivers’ decontextualized language input to children aged three to five is consistently correlated with kindergarten oral language skills and later reading achievement, it is surprising no experimental research has been done to establish this relation causally. The study described in this dissertation filled this literature gap by designing, implementing, and evaluating a decontextualized language training program for parents of 4-year-old children (N=30). After obtaining an initial measure of decontextualized language, parents were randomly assigned to a control condition or training condition, the latter of which educated parents about decontextualized language and why it is important. All parents then audio-recorded four mealtime conversations over the next month, which were transcribed and reliably coded for decontextualized language. Results indicated that trained parents boosted their DL from roughly 17 percent of their total utterances at baseline to approximately 50 percent by the mid-point of the study, and remained at these boosted levels throughout the duration of the study. Children’s DL was also boosted by similar margins, but no improvement in children’s oral language skills was observed, measured prior to, and one month following training. Further, exploratory analyses pointed to parents’ initial use of DL and their theories of the malleability of intelligence (i.e., growth mindsets) as moderators of training gains. Altogether, these findings are a first step in establishing DL as a viable strategy for giving children the oral language skills needed to begin kindergarten ready to succeed in the classroom.