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    Prefix Siphoning: Exploiting LSM-Tree Range Filters For Information Disclosure (Full Version)

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    Key-value stores typically leave access control to the systems for which they act as storage engines. Unfortunately, attackers may circumvent such read access controls via timing attacks on the key-value store, which use differences in query response times to glean information about stored data. To date, key-value store timing attacks have aimed to disclose stored values and have exploited external mechanisms that can be disabled for protection. In this paper, we point out that key disclosure is also a security threat -- and demonstrate key disclosure timing attacks that exploit mechanisms of the key-value store itself. We target LSM-tree based key-value stores utilizing range filters, which have been recently proposed to optimize LSM-tree range queries. We analyze the impact of the range filters SuRF and prefix Bloom filter on LSM-trees through a security lens, and show that they enable a key disclosure timing attack, which we call prefix siphoning. Prefix siphoning successfully leverages benign queries for non-present keys to identify prefixes of actual keys -- and in some cases, full keys -- in scenarios where brute force searching for keys (via exhaustive enumeration or random guesses) is infeasible.Comment: Full version of USENIX ATC'23 pape

    Biofuel as an alternative shipping fuel : technological, environmental and economic assessment

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    © Royal Society of Chemistry 2019Fossil derived fuels available for application within the maritime sector have been dominated by heavy fuel oil (HFO), which is conventionally used in low speed (main) engines, and more refined fuels such as marine diesel oil (MDO), which is consumed in fast or medium speed engines. However, increasing fuel costs and regulatory pressure such as the restrictions placed on sulphur content have increased interest in the use of alternative fuels. A number of alternative fuels have been identified and may be viable for use within the maritime sector including straight vegetable oil (SVO) as an alternative to HFO in low speed engines, biodiesel to replace MDO/MGO in low to medium speed engines and bio-liquefied natural gas (bio-LNG) in gas engines using LNG. The potential sources of biomass feedstocks, conversion pathways and technologies are identified. The key parameters limiting their potential application are examined, in particular, availability, technological development, technical integration, and operational consequences. A proposed solution to overcome these limitations is recommended. The effective implementation of these strategies will enable the more widespread use of biofuels in marine applications, significantly reducing emissions from ships and improving global air quality and also protecting the ecological environment.Peer reviewe
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