Commercial trusted third parties (TTPs) may increase their bottom line by watering down their validation procedures because they assume no liability for lapses of judgement. Consumers bear the risk of misplaced trust. Reputation loss is a weak deterrent for TTPs because consumers do not choose them - web shops and browser vendors do. At the same time, consumers are the source of income of these parties. Hence, risks and rewards are not well-aligned. Towards a better alignment, we explore the brokering of connection insurances and transaction insurances, where consumers get to choose their insurer. We lay out the principal idea how such a brokerage might work at a technical level with minimal interference with existing protocols and mechanisms, we analyze the security requirements and we propose techniques to meet these requirements.
{"title":"POSTER: Re-Thinking Risks and Rewards for Trusted Third Parties","authors":"J. Malchow, Benjamin Güldenring, Volker Roth","doi":"10.1145/2976749.2989060","DOIUrl":"https://doi.org/10.1145/2976749.2989060","url":null,"abstract":"Commercial trusted third parties (TTPs) may increase their bottom line by watering down their validation procedures because they assume no liability for lapses of judgement. Consumers bear the risk of misplaced trust. Reputation loss is a weak deterrent for TTPs because consumers do not choose them - web shops and browser vendors do. At the same time, consumers are the source of income of these parties. Hence, risks and rewards are not well-aligned. Towards a better alignment, we explore the brokering of connection insurances and transaction insurances, where consumers get to choose their insurer. We lay out the principal idea how such a brokerage might work at a technical level with minimal interference with existing protocols and mechanisms, we analyze the security requirements and we propose techniques to meet these requirements.","PeriodicalId":432261,"journal":{"name":"Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133851821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Tian, Adam Bates, Kevin R. B. Butler, R. Rangaswami
Defenders of enterprise networks have a critical need to quickly identify the root causes of malware and data leakage. Increasingly, USB storage devices are the media of choice for data exfiltration, malware propagation, and even cyber-warfare. We observe that a critical aspect of explaining and preventing such attacks is understanding the provenance of data (i.e., the lineage of data from its creation to current state) on USB devices as a means of ensuring their safe usage. Unfortunately, provenance tracking is not offered by even sophisticated modern devices. This work presents ProvUSB, an architecture for fine-grained provenance collection and tracking on smart USB devices. ProvUSB maintains data provenance by recording reads and writes at the block layer and reliably identifying hosts editing those blocks through attestation over the USB channel. Our evaluation finds that ProvUSB imposes a one-time 850 ms overhead during USB enumeration, but approaches nearly-bare-metal runtime performance (90% of throughput) on larger files during normal execution, and less than 0.1% storage overhead for provenance in real-world workloads. ProvUSB thus provides essential new techniques in the defense of computer systems and USB storage devices.
{"title":"ProvUSB: Block-level Provenance-Based Data Protection for USB Storage Devices","authors":"D. Tian, Adam Bates, Kevin R. B. Butler, R. Rangaswami","doi":"10.1145/2976749.2978398","DOIUrl":"https://doi.org/10.1145/2976749.2978398","url":null,"abstract":"Defenders of enterprise networks have a critical need to quickly identify the root causes of malware and data leakage. Increasingly, USB storage devices are the media of choice for data exfiltration, malware propagation, and even cyber-warfare. We observe that a critical aspect of explaining and preventing such attacks is understanding the provenance of data (i.e., the lineage of data from its creation to current state) on USB devices as a means of ensuring their safe usage. Unfortunately, provenance tracking is not offered by even sophisticated modern devices. This work presents ProvUSB, an architecture for fine-grained provenance collection and tracking on smart USB devices. ProvUSB maintains data provenance by recording reads and writes at the block layer and reliably identifying hosts editing those blocks through attestation over the USB channel. Our evaluation finds that ProvUSB imposes a one-time 850 ms overhead during USB enumeration, but approaches nearly-bare-metal runtime performance (90% of throughput) on larger files during normal execution, and less than 0.1% storage overhead for provenance in real-world workloads. ProvUSB thus provides essential new techniques in the defense of computer systems and USB storage devices.","PeriodicalId":432261,"journal":{"name":"Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133326230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
When a group of individuals and organizations wish to compute a stable matching---for example, when medical students are matched to medical residency programs---they often outsource the computation to a trusted arbiter in order to preserve the privacy of participants' preferences. Secure multi-party computation offers the possibility of private matching processes that do not rely on any common trusted third party. However, stable matching algorithms have previously been considered infeasible for execution in a secure multi-party context on non-trivial inputs because they are computationally intensive and involve complex data-dependent memory access patterns. We adapt the classic Gale-Shapley algorithm for use in such a context, and show experimentally that our modifications yield a lower asymptotic complexity and more than an order of magnitude in practical cost improvement over previous techniques. Our main improvements stem from designing new oblivious data structures that exploit the properties of the matching algorithms. We apply a similar strategy to scale the Roth-Peranson instability chaining algorithm, currently in use by the National Resident Matching Program. The resulting protocol is efficient enough to be useful at the scale required for matching medical residents nationwide, taking just over 18 hours to complete an execution simulating the 2016 national resident match with more than 35,000 participants and 30,000 residency slots.
{"title":"Secure Stable Matching at Scale","authors":"Jack Doerner, David Evans, Abhi Shelat","doi":"10.1145/2976749.2978373","DOIUrl":"https://doi.org/10.1145/2976749.2978373","url":null,"abstract":"When a group of individuals and organizations wish to compute a stable matching---for example, when medical students are matched to medical residency programs---they often outsource the computation to a trusted arbiter in order to preserve the privacy of participants' preferences. Secure multi-party computation offers the possibility of private matching processes that do not rely on any common trusted third party. However, stable matching algorithms have previously been considered infeasible for execution in a secure multi-party context on non-trivial inputs because they are computationally intensive and involve complex data-dependent memory access patterns. We adapt the classic Gale-Shapley algorithm for use in such a context, and show experimentally that our modifications yield a lower asymptotic complexity and more than an order of magnitude in practical cost improvement over previous techniques. Our main improvements stem from designing new oblivious data structures that exploit the properties of the matching algorithms. We apply a similar strategy to scale the Roth-Peranson instability chaining algorithm, currently in use by the National Resident Matching Program. The resulting protocol is efficient enough to be useful at the scale required for matching medical residents nationwide, taking just over 18 hours to complete an execution simulating the 2016 national resident match with more than 35,000 participants and 30,000 residency slots.","PeriodicalId":432261,"journal":{"name":"Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security","volume":"240 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133432621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhenfeng Zhang, Kang Yang, Xuexian Hu, Yuchen Wang
Anonymous authentication allows one to authenticate herself without revealing her identity, and becomes an important technique for constructing privacy-preserving Internet connections. Anonymous password authentication is highly desirable as it enables a client to authenticate herself by a human-memorable password while preserving her privacy. In this paper, we introduce a novel approach for designing anonymous password-authenticated key exchange (APAKE) protocols using algebraic message authentication codes (MACs), where an algebraic MAC wrapped by a password is used by a client for anonymous authentication, and a server issues algebraic MACs to clients and acts as the verifier of login protocols. Our APAKE construction is secure provided that the algebraic MAC is strongly existentially unforgeable under random message and chosen verification queries attack (suf-rmva), weak pseudorandom and tag-randomization simulatable, and has simulation-sound extractable non-interactive zero-knowledge proofs (SE-NIZKs). To design practical APAKE protocols, we instantiate an algebraic MAC based on the q-SDH assumption which satisfies all the required properties, and construct credential presentation algorithms for the MAC which have optimal efficiency for a randomize-then-prove paradigm. Based on the algebraic MAC, we instantiate a highly practical APAKE protocol and denote it by APAKE, which is much more efficient than the mechanisms specified by ISO/IEC 20009-4. An efficient revocation mechanism for APAKE is also proposed. We integrate APAKE into TLS to present an anonymous client authentication mode where clients holding passwords can authenticate themselves to a server anonymously. Our implementation with 128-bit security shows that the average connection time of APAKE-based ciphersuite is 2.8 ms. With APAKE integrated into the OpenSSL library and using an Apache web server on a 2-core desktop computer, we could serve 953 ECDHE-ECDSA-AES128-GCM-SHA256 HTTPS connections per second for a 10 KB payload. Compared to ECDSA-signed elliptic curve Diffie-Hellman ciphersuite with mutual authentication, this means a 0.27 KB increased handshake size and a 13% reduction in throughput.
{"title":"Practical Anonymous Password Authentication and TLS with Anonymous Client Authentication","authors":"Zhenfeng Zhang, Kang Yang, Xuexian Hu, Yuchen Wang","doi":"10.1145/2976749.2978354","DOIUrl":"https://doi.org/10.1145/2976749.2978354","url":null,"abstract":"Anonymous authentication allows one to authenticate herself without revealing her identity, and becomes an important technique for constructing privacy-preserving Internet connections. Anonymous password authentication is highly desirable as it enables a client to authenticate herself by a human-memorable password while preserving her privacy. In this paper, we introduce a novel approach for designing anonymous password-authenticated key exchange (APAKE) protocols using algebraic message authentication codes (MACs), where an algebraic MAC wrapped by a password is used by a client for anonymous authentication, and a server issues algebraic MACs to clients and acts as the verifier of login protocols. Our APAKE construction is secure provided that the algebraic MAC is strongly existentially unforgeable under random message and chosen verification queries attack (suf-rmva), weak pseudorandom and tag-randomization simulatable, and has simulation-sound extractable non-interactive zero-knowledge proofs (SE-NIZKs). To design practical APAKE protocols, we instantiate an algebraic MAC based on the q-SDH assumption which satisfies all the required properties, and construct credential presentation algorithms for the MAC which have optimal efficiency for a randomize-then-prove paradigm. Based on the algebraic MAC, we instantiate a highly practical APAKE protocol and denote it by APAKE, which is much more efficient than the mechanisms specified by ISO/IEC 20009-4. An efficient revocation mechanism for APAKE is also proposed. We integrate APAKE into TLS to present an anonymous client authentication mode where clients holding passwords can authenticate themselves to a server anonymously. Our implementation with 128-bit security shows that the average connection time of APAKE-based ciphersuite is 2.8 ms. With APAKE integrated into the OpenSSL library and using an Apache web server on a 2-core desktop computer, we could serve 953 ECDHE-ECDSA-AES128-GCM-SHA256 HTTPS connections per second for a 10 KB payload. Compared to ECDSA-signed elliptic curve Diffie-Hellman ciphersuite with mutual authentication, this means a 0.27 KB increased handshake size and a 13% reduction in throughput.","PeriodicalId":432261,"journal":{"name":"Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130216364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cache side-channel attacks have been extensively studied on x86 architectures, but much less so on ARM processors. The technical challenges to conduct side-channel attacks on ARM, presumably, stem from the poorly documented ARM cache implementations, such as cache coherence protocols and cache flush operations, and also the lack of understanding of how different cache implementations will affect side-channel attacks. This paper presents a systematic exploration of vectors for flush-reload attacks on ARM processors. flush-reload attacks are among the most well-known cache side-channel attacks on x86. It has been shown in previous work that they are capable of exfiltrating sensitive information with high fidelity. We demonstrate in this work a novel construction of flush-reload side channels on last-level caches of ARM processors, which, particularly, exploits return-oriented programming techniques to reload instructions. We also demonstrate several attacks on Android OS (e.g., detecting hardware events and tracing software execution paths) to highlight the implications of such attacks for Android devices.
{"title":"Return-Oriented Flush-Reload Side Channels on ARM and Their Implications for Android Devices","authors":"Xiaokuan Zhang, Yuan Xiao, Yinqian Zhang","doi":"10.1145/2976749.2978360","DOIUrl":"https://doi.org/10.1145/2976749.2978360","url":null,"abstract":"Cache side-channel attacks have been extensively studied on x86 architectures, but much less so on ARM processors. The technical challenges to conduct side-channel attacks on ARM, presumably, stem from the poorly documented ARM cache implementations, such as cache coherence protocols and cache flush operations, and also the lack of understanding of how different cache implementations will affect side-channel attacks. This paper presents a systematic exploration of vectors for flush-reload attacks on ARM processors. flush-reload attacks are among the most well-known cache side-channel attacks on x86. It has been shown in previous work that they are capable of exfiltrating sensitive information with high fidelity. We demonstrate in this work a novel construction of flush-reload side channels on last-level caches of ARM processors, which, particularly, exploits return-oriented programming techniques to reload instructions. We also demonstrate several attacks on Android OS (e.g., detecting hardware events and tracing software execution paths) to highlight the implications of such attacks for Android devices.","PeriodicalId":432261,"journal":{"name":"Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114977136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vulnerability management, often used as a generic term for any organizational and technical security controls in the context of identifying, assessing, and mitigating security-relevant software and network weaknesses, has specific challenges in decentralized communication networks such as research and education networks operated by higher education institutions. While many large organizations perform professional vulnerability management and related activities, especially risk management, which are supported by commercial and open source software products, universities and other academic environments still often struggle with ad-hoc and scope-limited approaches due to often unclear responsibilities and a lack of suitable tool support. This poster presents VUDEC, an integrated vulnerability management framework tailored for the requirements of decentrally operated networks; besides organizational aspects of the vulnerability management process, its implementation supports, among other functionality, a highly distributed vulnerability scan architecture and full multi-tenancy capability.
{"title":"POSTER: VUDEC: A Framework for Vulnerability Management in Decentralized Communication Networks","authors":"M. Steinke, Stefan Metzger, Wolfgang Hommel","doi":"10.1145/2976749.2989049","DOIUrl":"https://doi.org/10.1145/2976749.2989049","url":null,"abstract":"Vulnerability management, often used as a generic term for any organizational and technical security controls in the context of identifying, assessing, and mitigating security-relevant software and network weaknesses, has specific challenges in decentralized communication networks such as research and education networks operated by higher education institutions. While many large organizations perform professional vulnerability management and related activities, especially risk management, which are supported by commercial and open source software products, universities and other academic environments still often struggle with ad-hoc and scope-limited approaches due to often unclear responsibilities and a lack of suitable tool support. This poster presents VUDEC, an integrated vulnerability management framework tailored for the requirements of decentrally operated networks; besides organizational aspects of the vulnerability management process, its implementation supports, among other functionality, a highly distributed vulnerability scan architecture and full multi-tenancy capability.","PeriodicalId":432261,"journal":{"name":"Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132367359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jun Xu, Dongliang Mu, Ping Chen, Xinyu Xing, Pei Wang, Peng Liu
After a program has crashed and terminated abnormally, it typically leaves behind a snapshot of its crashing state in the form of a core dump. While a core dump carries a large amount of information, which has long been used for software debugging, it barely serves as informative debugging aids in locating software faults, particularly memory corruption vulnerabilities. A memory corruption vulnerability is a special type of software faults that an attacker can exploit to manipulate the content at a certain memory. As such, a core dump may contain a certain amount of corrupted data, which increases the difficulty in identifying useful debugging information (e.g. , a crash point and stack traces). Without a proper mechanism to deal with this problem, a core dump can be practically useless for software failure diagnosis. In this work, we develop CREDAL, an automatic tool that employs the source code of a crashing program to enhance core dump analysis and turns a core dump to an informative aid in tracking down memory corruption vulnerabilities. Specifically, CREDAL systematically analyzes a core dump potentially corrupted and identifies the crash point and stack frames. For a core dump carrying corrupted data, it goes beyond the crash point and stack trace. In particular, CREDAL further pinpoints the variables holding corrupted data using the source code of the crashing program along with the stack frames. To assist software developers (or security analysts) in tracking down a memory corruption vulnerability, CREDAL also performs analysis and highlights the code fragments corresponding to data corruption. To demonstrate the utility of CREDAL, we use it to analyze 80 crashes corresponding to 73 memory corruption vulnerabilities archived in Offensive Security Exploit Database. We show that, CREDAL can accurately pinpoint the crash point and (fully or partially) restore a stack trace even though a crashing program stack carries corrupted data. In addition, we demonstrate CREDAL can potentially reduce the manual effort of finding the code fragment that is likely to contain memory corruption vulnerabilities.
{"title":"CREDAL","authors":"Jun Xu, Dongliang Mu, Ping Chen, Xinyu Xing, Pei Wang, Peng Liu","doi":"10.1145/2976749.2978340","DOIUrl":"https://doi.org/10.1145/2976749.2978340","url":null,"abstract":"After a program has crashed and terminated abnormally, it typically leaves behind a snapshot of its crashing state in the form of a core dump. While a core dump carries a large amount of information, which has long been used for software debugging, it barely serves as informative debugging aids in locating software faults, particularly memory corruption vulnerabilities. A memory corruption vulnerability is a special type of software faults that an attacker can exploit to manipulate the content at a certain memory. As such, a core dump may contain a certain amount of corrupted data, which increases the difficulty in identifying useful debugging information (e.g. , a crash point and stack traces). Without a proper mechanism to deal with this problem, a core dump can be practically useless for software failure diagnosis. In this work, we develop CREDAL, an automatic tool that employs the source code of a crashing program to enhance core dump analysis and turns a core dump to an informative aid in tracking down memory corruption vulnerabilities. Specifically, CREDAL systematically analyzes a core dump potentially corrupted and identifies the crash point and stack frames. For a core dump carrying corrupted data, it goes beyond the crash point and stack trace. In particular, CREDAL further pinpoints the variables holding corrupted data using the source code of the crashing program along with the stack frames. To assist software developers (or security analysts) in tracking down a memory corruption vulnerability, CREDAL also performs analysis and highlights the code fragments corresponding to data corruption. To demonstrate the utility of CREDAL, we use it to analyze 80 crashes corresponding to 73 memory corruption vulnerabilities archived in Offensive Security Exploit Database. We show that, CREDAL can accurately pinpoint the crash point and (fully or partially) restore a stack trace even though a crashing program stack carries corrupted data. In addition, we demonstrate CREDAL can potentially reduce the manual effort of finding the code fragment that is likely to contain memory corruption vulnerabilities.","PeriodicalId":432261,"journal":{"name":"Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128607797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaocong Jin, Rui Zhang, Yimin Chen, Tao Li, Yanchao Zhang
Dynamic spectrum access (DSA) has great potential to address worldwide spectrum shortage by enhancing spectrum efficiency. It allows unlicensed secondary users to access the underutilized licensed spectrum when the licensed primary users are not transmitting. As a key enabler for DSA systems, crowdsourced spectrum sensing (CSS) allows a spectrum sensing provider (SSP) to outsource the sensing of spectrum occupancy to distributed mobile users. In this paper, we propose DPSense, a novel framework that allows the SSP to select mobile users for executing spatiotemporal spectrum-sensing tasks without violating the location privacy of mobile users. Detailed evaluations on real location traces confirm that DPSense can provide differential location privacy to mobile users while ensuring that the SSP can accomplish spectrum-sensing tasks with overwhelming probability and also the minimal cost.
{"title":"DPSense: Differentially Private Crowdsourced Spectrum Sensing","authors":"Xiaocong Jin, Rui Zhang, Yimin Chen, Tao Li, Yanchao Zhang","doi":"10.1145/2976749.2978426","DOIUrl":"https://doi.org/10.1145/2976749.2978426","url":null,"abstract":"Dynamic spectrum access (DSA) has great potential to address worldwide spectrum shortage by enhancing spectrum efficiency. It allows unlicensed secondary users to access the underutilized licensed spectrum when the licensed primary users are not transmitting. As a key enabler for DSA systems, crowdsourced spectrum sensing (CSS) allows a spectrum sensing provider (SSP) to outsource the sensing of spectrum occupancy to distributed mobile users. In this paper, we propose DPSense, a novel framework that allows the SSP to select mobile users for executing spatiotemporal spectrum-sensing tasks without violating the location privacy of mobile users. Detailed evaluations on real location traces confirm that DPSense can provide differential location privacy to mobile users while ensuring that the SSP can accomplish spectrum-sensing tasks with overwhelming probability and also the minimal cost.","PeriodicalId":432261,"journal":{"name":"Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security","volume":"221 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133617650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Oblivious RAM (ORAM) mechanisms have improved rapidly in recent years as increasing amounts of data are outsourced. Although several tree-based ORAMs such as PathORAM [8] and RingORAM [6] have achieved near-optimal bandwidth for single client scenarios, their low overall throughput due to high latency of access -- as clients need to wait for or know about and coordinate with each other, lest privacy is lost -- reduces their applicability for multi-client scenarios. In this paper, we propose ConcurORAM, a multi-client concurrent ORAM that eliminates waiting for concurrent clients and significantly increases overall throughput. ConcurORAM works by securely allowing multiple clients to asynchronously access the data set in between eviction rounds by judiciously storing ORAM position map data in a smaller parallel de-amortized pyramid ORAM [10] of higher complexity. In effect ConcurORAM reaps the benefits of parallelism at a lower O(log(N)) overall complexity by identifying and securely accessing the absolute critical data structures that require parallel access with privacy (position map) and designing everything else using append-only data structures that can be then merged securely in a separate eviction step.
{"title":"POSTER: ConcurORAM: High-Throughput Parallel Multi-Client ORAM","authors":"Anrin Chakraborti, R. Sion","doi":"10.1145/2976749.2989062","DOIUrl":"https://doi.org/10.1145/2976749.2989062","url":null,"abstract":"Oblivious RAM (ORAM) mechanisms have improved rapidly in recent years as increasing amounts of data are outsourced. Although several tree-based ORAMs such as PathORAM [8] and RingORAM [6] have achieved near-optimal bandwidth for single client scenarios, their low overall throughput due to high latency of access -- as clients need to wait for or know about and coordinate with each other, lest privacy is lost -- reduces their applicability for multi-client scenarios. In this paper, we propose ConcurORAM, a multi-client concurrent ORAM that eliminates waiting for concurrent clients and significantly increases overall throughput. ConcurORAM works by securely allowing multiple clients to asynchronously access the data set in between eviction rounds by judiciously storing ORAM position map data in a smaller parallel de-amortized pyramid ORAM [10] of higher complexity. In effect ConcurORAM reaps the benefits of parallelism at a lower O(log(N)) overall complexity by identifying and securely accessing the absolute critical data structures that require parallel access with privacy (position map) and designing everything else using append-only data structures that can be then merged securely in a separate eviction step.","PeriodicalId":432261,"journal":{"name":"Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security","volume":"228 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133772083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Arthur Gervais, Ghassan O. Karame, K. Wüst, Vasileios Glykantzis, H. Ritzdorf, Srdjan Capkun
Proof of Work (PoW) powered blockchains currently account for more than 90% of the total market capitalization of existing digital cryptocurrencies. Although the security provisions of Bitcoin have been thoroughly analysed, the security guarantees of variant (forked) PoW blockchains (which were instantiated with different parameters) have not received much attention in the literature. This opens the question whether existing security analysis of Bitcoin's PoW applies to other implementations which have been instantiated with different consensus and/or network parameters. In this paper, we introduce a novel quantitative framework to analyse the security and performance implications of various consensus and network parameters of PoW blockchains. Based on our framework, we devise optimal adversarial strategies for double-spending and selfish mining while taking into account real world constraints such as network propagation, different block sizes, block generation intervals, information propagation mechanism, and the impact of eclipse attacks. Our framework therefore allows us to capture existing PoW-based deployments as well as PoW blockchain variants that are instantiated with different parameters, and to objectively compare the tradeoffs between their performance and security provisions.
{"title":"On the Security and Performance of Proof of Work Blockchains","authors":"Arthur Gervais, Ghassan O. Karame, K. Wüst, Vasileios Glykantzis, H. Ritzdorf, Srdjan Capkun","doi":"10.1145/2976749.2978341","DOIUrl":"https://doi.org/10.1145/2976749.2978341","url":null,"abstract":"Proof of Work (PoW) powered blockchains currently account for more than 90% of the total market capitalization of existing digital cryptocurrencies. Although the security provisions of Bitcoin have been thoroughly analysed, the security guarantees of variant (forked) PoW blockchains (which were instantiated with different parameters) have not received much attention in the literature. This opens the question whether existing security analysis of Bitcoin's PoW applies to other implementations which have been instantiated with different consensus and/or network parameters. In this paper, we introduce a novel quantitative framework to analyse the security and performance implications of various consensus and network parameters of PoW blockchains. Based on our framework, we devise optimal adversarial strategies for double-spending and selfish mining while taking into account real world constraints such as network propagation, different block sizes, block generation intervals, information propagation mechanism, and the impact of eclipse attacks. Our framework therefore allows us to capture existing PoW-based deployments as well as PoW blockchain variants that are instantiated with different parameters, and to objectively compare the tradeoffs between their performance and security provisions.","PeriodicalId":432261,"journal":{"name":"Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133642673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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