6 research outputs found

    Authenticated LSM Trees with Minimal Trust

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    In the age of user-generated contents, the workloads imposed on information-security infrastructures become increasingly write-intensive. How- ever, existing security protocols, specifically authenticated data structures (ADSs), are historically designed based on update-in-place data structures and incur overhead when serving write-intensive workloads. In this work, we present LPAD (Log-structured Persistent Authenticated Directory), a new ADS protocol designed uniquely based on the log-structured merge trees (LSM trees) which recently gained popularity in the design of modern storage systems. On the write path, LPAD supports streaming, non-interactive updates with constant proof from trusted data owners. On the read path, LPAD supports point queries over the dynamic dataset with polynomial proof. The key to enable this efficiency is a verifiable reorganization operation, called verifiable merge, in LPAD. Verifiable merge is secured by the execution in an enclave of trusted execution environments (TEE). To minimize the trusted computing base (TCB), LPAD places the code related to verifiable merge in enclave, and nothing else. Our implementation of LPAD on Google LevelDB codebase and on Intel SGX shows that the TCB is reduced by 20 times: The enclave size of LPAD is one thousand code lines out of more than twenty thousands code lines of a vanilla LevelDB. Under the YCSB workloads, LPAD improves the performance by an order of magnitude compared with that of existing update-in-place ADSs

    The economic fate of urban settlements in Rhomanian Boeotia, Thessaly, and Western Macedonia (783-1204)

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    Although there are enough studies on the economic history of late 8th-early 13th century Rhomanian Greece (for my use of the term ‘Rhomanian’ rather than ‘Byzantine’, see the end of section I) to warrant years of intensive reading, few of them are regional or multi-regional in their scope. Largescale interpretations have been correspondingly few. The most noteworthy one – with regard to the regions that I am studying – is that Boeotia was home to one of the finest silk industries in the Empire in the late 11th-12th centuries. Using all available sources of information (ecclesiastical, hagiographical, geographic monographs, court chronicles, weather station statistics, archaeological monuments and artifacts, and so on), I examined urban settlements based on five main criteria: the quality and pervasiveness of ceramic material, the distribution of currency, the presence of a Jewish population, the incidence of sigillographic data, the magnitude, quality, and frequency of architectural projects, and the size and number of settlements. I found that there is ample evidence for growth in the domains of demography, silk production (whose quantitative element still hangs in the balance, however), exports to Constantinople, religious construction projects, coin use, and high-quality production imports/production.These trends are then probed for natural and human explanations, and used to discuss the relationship between my regions of study and Rhomania as a whole
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