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Hardening Stratum, the Bitcoin Pool Mining Protocol [article]

Ruben Recabarren, Bogdan Carbunar
2017 arXiv   pre-print
Stratum, the de-facto mining communication protocol used by blockchain based cryptocurrency systems, enables miners to reliably and efficiently fetch jobs from mining pool servers. In this paper we exploit Stratum's lack of encryption to develop passive and active attacks on Bitcoin's mining protocol, with important implications on the privacy, security and even safety of mining equipment owners. We introduce StraTap and ISP Log attacks, that infer miner earnings if given access to miner
more » ... cations, or even their logs. We develop BiteCoin, an active attack that hijacks shares submitted by miners, and their associated payouts. We build BiteCoin on WireGhost, a tool we developed to hijack and surreptitiously maintain Stratum connections. Our attacks reveal that securing Stratum through pervasive encryption is not only undesirable (due to large overheads), but also ineffective: an adversary can predict miner earnings even when given access to only packet timestamps. Instead, we devise Bedrock, a minimalistic Stratum extension that protects the privacy and security of mining participants. We introduce and leverage the mining cookie concept, a secret that each miner shares with the pool and includes in its puzzle computations, and that prevents attackers from reconstructing or hijacking the puzzles. We have implemented our attacks and collected 138MB of Stratum protocol traffic from mining equipment in the US and Venezuela. We show that Bedrock is resilient to active attacks even when an adversary breaks the crypto constructs it uses. Bedrock imposes a daily overhead of 12.03s on a single pool server that handles mining traffic from 16,000 miners.
arXiv:1703.06545v1 fatcat:3paoaxfzt5csvcmboawut4lzmi

Tithonus: A Bitcoin Based Censorship Resilient System [article]

Ruben Recabarren, Bogdan Carbunar
2018 arXiv   pre-print
Providing reliable and surreptitious communications is difficult in the presence of adaptive and resourceful state level censors. In this paper we introduce Tithonus, a framework that builds on the Bitcoin blockchain and network to provide censorship-resistant communication mechanisms. In contrast to previous approaches, we do not rely solely on the slow and expensive blockchain consensus mechanism but instead fully exploit Bitcoin's peer-to-peer gossip protocol. We develop adaptive, fast and
more » ... st effective data communication solutions that camouflage client requests into inconspicuous Bitcoin transactions. We propose solutions to securely request and transfer content, with unobservability and censorship resistance, and free, pay-per-access and subscription based payment options. When compared to state-of-the-art Bitcoin writing solutions, Tithonus reduces the cost of transferring data to censored clients by 2 orders of magnitude and increases the goodput by 3 to 5 orders of magnitude. We show that Tithonus client initiated transactions are hard to detect, while server initiated transactions cannot be censored without creating split world problems to the Bitcoin blockchain.
arXiv:1810.00279v1 fatcat:47eagj5sj5cfpgmjo6fx4kpof4

Toward Uncensorable, Anonymous and Private Access Over Satoshi Blockchains [article]

Ruben Recabarren, Bogdan Carbunar
2021 arXiv   pre-print
Introduction Basic human rights continue to be eroded around the world through fine-grained monitoring of Internet ac-*Corresponding Author: Ruben Recabarren: Florida International University, Miami, FL  ... 
arXiv:2110.08422v1 fatcat:3tqa2l7xljbwfdne247ofzqviy

Tithonus: A Bitcoin Based Censorship Resilient System

Ruben Recabarren, Bogdan Carbunar
2019 Proceedings on Privacy Enhancing Technologies  
Providing reliable and surreptitious communications is difficult in the presence of adaptive and resourceful state level censors. In this paper we introduce Tithonus, a framework that builds on the Bitcoin blockchain and network to provide censorship-resistant communication mechanisms. In contrast to previous approaches, we do not rely solely on the slow and expensive blockchain consensus mechanism but instead fully exploit Bitcoin's peer-to-peer gossip protocol. We develop adaptive, fast and
more » ... st effective data communication solutions that camouflage client requests into inconspicuous Bitcoin transactions. We propose solutions to securely request and transfer content, with unobservability and censorship resistance, and free, pay-per-access and subscription based payment options. When compared to state-of-the-art Bitcoin writing solutions, Tithonus reduces the cost of transferring data to censored clients by 2 orders of magnitude and increases the goodput by 3 to 5 orders of magnitude. We show that Tithonus client initiated transactions are hard to detect, while server initiated transactions cannot be censored without creating split world problems to the Bit-coin blockchain.
doi:10.2478/popets-2019-0005 dblp:journals/popets/RecabarrenC19 fatcat:2pjsytmi7faphmcykdq2wo5zau

Hardening Stratum, the Bitcoin Pool Mining Protocol

Ruben Recabarren, Bogdan Carbunar
2017 Proceedings on Privacy Enhancing Technologies  
Stratum, the de-facto mining communication protocol used by blockchain based cryptocurrency systems, enables miners to reliably and efficiently fetch jobs from mining pool servers. In this paper we exploit Stratum's lack of encryption to develop passive and active attacks on Bitcoin's mining protocol, with important implications on the privacy, security and even safety of mining equipment owners. We introduce StraTap and ISP Log attacks, that infer miner earnings if given access to miner
more » ... cations, or even their logs. We develop BiteCoin, an active attack that hijacks shares submitted by miners, and their associated payouts. We build BiteCoin on WireGhost, a tool we developed to hijack and surreptitiously maintain Stratum connections. Our attacks reveal that securing Stratum through pervasive encryption is not only undesirable (due to large overheads), but also ineffective: an adversary can predict miner earnings even when given access to only packet timestamps. Instead, we devise Bedrock, a minimalistic Stratum extension that protects the privacy and security of mining participants. We introduce and leverage the mining cookie concept, a secret that each miner shares with the pool and includes in its puzzle computations, and that prevents attackers from reconstructing or hijacking the puzzles. We have implemented our attacks and collected 138MB of Stratum protocol traffic from mining equipment in the US and Venezuela. We show that Bedrock is resilient to active attacks even when an adversary breaks the crypto constructs it uses. Bedrock imposes a daily overhead of 12.03s on a single pool server that handles mining traffic from 16,000 miners.
doi:10.1515/popets-2017-0028 dblp:journals/popets/RecabarrenC17 fatcat:t3zo2fcv5ncyzbr7jz64ulv7i4

Estimating the total number of protein folds

Sridhar Govindarajan, Ruben Recabarren, Richard A. Goldstein
1999 Proteins: Structure, Function, and Bioinformatics  
Many seemingly unrelated protein families share common folds. Theoretical models based on structure designability have suggested that a few folds should be very common while many others have low probability. In agreement with the predictions of these models, we show that the distribution of observed protein families over different folds can be modeled with a highly-stretched exponential. Our results suggest that there are approximately 4,000 possible folds, some so unlikely that only
more » ... ly 2,000 folds existing among naturallyoccurring proteins. Due to the large number of extremely rare folds, constructing a comprehensive database of all existent folds would be difficult. Constructing a database of the most-likely folds representing the vast majority of protein families would be considerably easier. Proteins 1999;35:408-414.
doi:10.1002/(sici)1097-0134(19990601)35:4<408::aid-prot4>3.3.co;2-1 pmid:10382668 fatcat:524sgodftbg4vik3j2g5pq6z3a

Estimating the total number of protein folds

Sridhar Govindarajan, Ruben Recabarren, Richard A. Goldstein
1999 Proteins: Structure, Function, and Bioinformatics  
Many seemingly unrelated protein families share common folds. Theoretical models based on structure designability have suggested that a few folds should be very common while many others have low probability. In agreement with the predictions of these models, we show that the distribution of observed protein families over different folds can be modeled with a highly-stretched exponential. Our results suggest that there are approximately 4,000 possible folds, some so unlikely that only
more » ... ly 2,000 folds existing among naturallyoccurring proteins. Due to the large number of extremely rare folds, constructing a comprehensive database of all existent folds would be difficult. Constructing a database of the most-likely folds representing the vast majority of protein families would be considerably easier. Proteins 1999;35:408-414.
doi:10.1002/(sici)1097-0134(19990601)35:4<408::aid-prot4>3.0.co;2-a pmid:10382668 fatcat:chslysq66fbz7dm37as7uw5ip4

Toward Uncensorable, Anonymous and Private Access Over Satoshi Blockchains

Ruben Recabarren, Bogdan Carbunar
2021 Proceedings on Privacy Enhancing Technologies  
Providing unrestricted access to sensitive content such as news and software is difficult in the presence of adaptive and resourceful surveillance and censoring adversaries. In this paper we leverage the distributed and resilient nature of commercial Satoshi blockchains to develop the first provably secure, censorship resistant, cost-efficient storage system with anonymous and private access, built on top of commercial cryptocurrency transactions. We introduce max-rate transactions, a practical
more » ... construct to persist data of arbitrary size entirely in a Satoshi blockchain. We leverage max-rate transactions to develop UWeb, a blockchain-based storage system that charges publishers to self-sustain its decentralized infrastructure. UWeb organizes blockchain-stored content for easy retrieval, and enables clients to store and access content with provable anonymity, privacy and censorship resistance properties. We present results from UWeb experiments with writing 268.21 MB of data into the live Litecoin blockchain, including 4.5 months of live-feed BBC articles, and 41 censorship resistant tools. The max-rate writing throughput (183 KB/s) and blockchain utilization (88%) exceed those of state-of-the-art solutions by 2-3 orders of magnitude and broke Litecoin's record of the daily average block size. Our simulations with up to 3,000 concurrent UWeb writers confirm that UWeb does not impact the confirmation delays of financial transactions.
doi:10.2478/popets-2022-0011 fatcat:d5bkmjp7xbevrnlcdtyy2aynne

RacketStore: Measurements of ASO Deception in Google Play via Mobile and App Usage [article]

Nestor Hernandez, Ruben Recabarren, Bogdan Carbunar, Syed Ishtiaque Ahmed
2021 arXiv   pre-print
Online app search optimization (ASO) platforms that provide bulk installs and fake reviews for paying app developers in order to fraudulently boost their search rank in app stores, were shown to employ diverse and complex strategies that successfully evade state-of-the-art detection methods. In this paper we introduce RacketStore, a platform to collect data from Android devices of participating ASO providers and regular users, on their interactions with apps which they install from the Google
more » ... ay Store. We present measurements from a study of 943 installs of RacketStore on 803 unique devices controlled by ASO providers and regular users, that consists of 58,362,249 data snapshots collected from these devices, the 12,341 apps installed on them and their 110,511,637 Google Play reviews. We reveal significant differences between ASO providers and regular users in terms of the number and types of user accounts registered on their devices, the number of apps they review, and the intervals between the installation times of apps and their review times. We leverage these insights to introduce features that model the usage of apps and devices, and show that they can train supervised learning algorithms to detect paid app installs and fake reviews with an F1-measure of 99.72% (AUC above 0.99), and detect devices controlled by ASO providers with an F1-measure of 95.29% (AUC = 0.95). We discuss the costs associated with evading detection by our classifiers and also the potential for app stores to use our approach to detect ASO work with privacy.
arXiv:2111.10400v1 fatcat:bq3uijeizjdbpfrukdao67mgla

Stateless Puzzles for Real Time Online Fraud Preemption

Mizanur Rahman, Ruben Recabarren, Bogdan Carbunar, Dongwon Lee
2017 Proceedings of the 2017 ACM on Web Science Conference - WebSci '17  
The profitability of fraud in online systems such as app markets and social networks marks the failure of existing defense mechanisms. In this paper, we propose FraudSys, a real-time fraud preemption approach that imposes Bitcoin-inspired computational puzzles on the devices that post online system activities, such as reviews and likes. We introduce and leverage several novel concepts that include (i) stateless, verifiable computational puzzles, that impose minimal performance overhead, but
more » ... le the efficient verification of their authenticity, (ii) a real-time, graph-based solution to assign fraud scores to user activities, and (iii) mechanisms to dynamically adjust puzzle difficulty levels based on fraud scores and the computational capabilities of devices. FraudSys does not alter the experience of users in online systems, but delays fraudulent actions and consumes significant computational resources of the fraudsters. Using real datasets from Google Play and Facebook, we demonstrate the feasibility of FraudSys by showing that the devices of honest users are minimally impacted, while fraudster controlled devices receive daily computational penalties of up to 3,079 hours. In addition, we show that with FraudSys, fraud does not pay off, as a user equipped with mining hardware (e.g., AntMiner S7) will earn less than half through fraud than from honest Bitcoin mining.
doi:10.1145/3091478.3091507 dblp:conf/websci/RahmanRCL17 fatcat:jeftvwglqfd4vbqa7cnph3egvq

ESTUDIO DE LA CONCENTRACIÓN DE ARSÉNICO, MERCURIO, PLOMO Y FENANTRENO EN LA MACHA (Mesodesma donacium): IMPLICANCIAS ALIMENTARIAS Y TOXICOLOGICAS

Oscar Díaz S, Francisco Encina M, Estela Recabarren G, Sergia Del Valle C, Rubén Pastene O, Sergio Montes S, Angélica Figueroa Q
2008 Revista Chilena de Nutricíon  
Este trabajo fue recibido el 26 de Diciembre de 2007 y aceptado para ser publicado el 18 de Marzo de 2008. ABSTRACT The coastal environment around the Maipo river outlet in the proximity of San Antonio bay (Vth Region, Chile) it is one of the most contaminated zone of the country due to discharges of industrial wastes on the river that affect the marine environment. The surf clam (Mesodesma donacium, Lamarck 1818) a benthic organism that provides an important source of seafood for human
more » ... ion is caught in this area. The total arsenic and mercury, lead and phenanthrene concentrations in the soft body of the surf clam were measured. The concentration of the elements in the marine organism fluctuated between 1,23-1,33 µg/g As, 0,26-0,39 µg/g Hg, and 0,23-0,33 µg/g Pb (dry basis). Phenanthrene was not detected in the samples. In spite of the high concentration of the elements detected in the surf clam, only in the case of Hg their intake could imply a certain grade of risk for human health, especially for young humans. Chronic effects, such as personality changes, neurological damage and others, could exhibit in the medium term. Therefore, it is important to carry out regular food surveillance studies, especially oriented to the specie specific aspect of toxic elements and monitoring of polyaromatic hydrocarbons (PAH) in several marine food.
doi:10.4067/s0717-75182008000100007 fatcat:xnupitonqjeabnx6djlj3aacau

European Extremely Large Telescope Site Characterization I: Overview

Jean Vernin, Casiana Muñoz-Tuñón, Marc Sarazin, Héctor Vazquez Ramió, Antonia M. Varela, Hervé Trinquet, José Miguel Delgado, Jesús Jiménez Fuensalida, Marcos Reyes, Abdelmajid Benhida, Zouhair Benkhaldoun, Diego García Lambas (+8 others)
2011 Publications of the Astronomical Society of the Pacific  
The site for the future European Extremely Large Telescope (E-ELT) is already known to be Armazones, near Paranal (Chile). The selection was based on a variety of considerations, with an important one being the quality of the atmosphere for the astronomy planned for the ELT. We present an overview of the characterization of the atmospheric parameters of candidate sites, making use of standard procedures and instruments as carried out within the Framework Programme VI (FP6) of the European
more » ... We have achieved full characterization of the selected sites for the parameters considered. Further details on adaptive optics results and climatology will be the subject of two forthcoming articles. A summary of the results of the FP6 site-testing campaigns at the different sites is provided.
doi:10.1086/662995 fatcat:zjlhvqmzzvhmviq4mmupc6ssiq

European Extremely Large Telescope Site Characterization. II. High Angular Resolution Parameters

Héctor Vázquez Ramió, Jean Vernin, Casiana Muñoz-Tuñón, Marc Sarazin, Antonia M. Varela, Hervé Trinquet, José Miguel Delgado, Jesús J. Fuensalida, Marcos Reyes, Abdelmajid Benhida, Zouhair Benkhaldoun, Diego García Lambas (+8 others)
2012 Publications of the Astronomical Society of the Pacific  
This is the second article of a series devoted to European Extremely Large Telescope (E-ELT) site characterization. In this article we present the main properties of the parameters involved in high angular resolution observations from the data collected in the site testing campaign of the E-ELT during the Design Study (DS) phase. Observations were made in 2008 and 2009, in the four sites selected to shelter the future E-ELT (characterized under the ELT-DS contract): Aklim mountain in Morocco,
more » ... servatorio del Roque de los Muchachos (ORM) in Spain, Mac\'on range in Argentina, and Cerro Ventarrones in Chile. The same techniques, instruments and acquisition procedures were taken on each site. A Multiple Aperture Scintillation Sensor (MASS) and a Differential Image Motion Monitor (DIMM) were installed at each site. Global statistics of the integrated seeing, the free atmosphere seeing, the boundary layer seeing and the isoplanatic angle were studied for each site, and the results are presented here. In order to estimate other important parameters such as the coherence time of the wavefront and the overall parameter "coherence \'etendue" additional information of vertical profiles of the wind speed was needed. Data were retrieved from the National Oceanic and Atmospheric Administration (NOAA) archive. Ground wind speed was measured by Automatic Weather Stations (AWS). More aspects of the turbulence parameters such as their seasonal trend, their nightly evolution and their temporal stability were also obtained and analyzed.
doi:10.1086/667599 fatcat:trk7cpsegzb4zmxf4i7cmwyig4

Page 435 of Hispanic American Report Vol. 16, Issue 5 [page]

1963 Hispanic American Report  
Non-Guatemalans caught in the wave of arrests were Oscar Recabarren, a Chilean and the local representative of the hemispheric labor Organizacién Regional Interamericana de Trabajadores (ORIT), which had  ...  Also exiled were a number of prom- inent student and union leaders, including Terencio Guillén Corleto, Edmundo Guerra Teilheimer, Rubén Barrera Avila, Marco Antonio Franco, Tomas Sierra Roldan, Max Armando  ... 

Robotics projects and learning concepts in science, technology and problem solving

Moshe Barak, Yair Zadok
2007 International Journal of Technology and Design Education  
., & Recabarren, M. (2009). Developing Cognition with Collaborative Robotic Activities. Educational Technology & Society, 12(4), 317-330. Mitnik, Ruben, Nussbaum, M., & Soto, A. (2008).  ... 
doi:10.1007/s10798-007-9043-3 fatcat:iztsdxn4qbgpfjwmxlqp674sza
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