The increasing popularity of cloud storage services has lead companies that handle critical data to think about using these for their needs. Medical record databases, power system historical information and financial are some examples could be moved the cloud. However, reliability security stored in still remain major concerns. In this paper we present DEPSKY, a improves availability, integrity confidentiality through encryption, encoding replication on diverse clouds form cloud-of-clouds....

The increasing popularity of cloud storage services has lead companies that handle critical data to think about using these for their needs. Medical record databases, large biomedical datasets, historical information power systems and financial are some examples could be moved the cloud. However, reliability security stored in still remain major concerns. In this work we present DepSky, a system improves availability, integrity, confidentiality through encryption, encoding, replication on...

We present two asynchronous Byzantine fault-tolerant state machine replication (BFT) algorithms, which improve previous algorithms in terms of several metrics. First, they require only 2f+1 replicas, instead the usual 3f+1. Second, trusted service this reduction replicas is based quite simple, making a verified implementation straightforward (and even feasible using commercial hardware). Third, nice executions run minimum number communication steps for nonspeculative and speculative...

Cloud Computing is a recent paradigm that creating high expectations about benefits such as the pay-per-use model and elasticity of resources. However, with this optimism come also concerns security. In public cloud, user's data storage processing no longer done inside its premises, but in centers owned administrated by cloud provider. This may be concern for organizations deal critical data, medical records. We show malicious insider can steal confidential user, so user mostly left trusting...

Most Byzantine fault-tolerant state machine replication (BFT) algorithms have a primary replica that is in charge of ordering the clients requests. Recently it was shown this dependence allows faulty to degrade performance system small fraction what environment allows. In paper we present Spinning, novel BFT algorithm mitigates such attacks by changing after every batch pending requests accepted for execution. This mode operation deals with those at much lower cost than previous solutions,...

In the past, some research has been done on how to use proactive recovery build intrusion-tolerant replicated systems that are resilient any number of faults, as long recoveries faster than an upper bound fault production assumed at system deployment time. this paper, we propose a complementary approach enhances with additional reactive mechanisms giving correct replicas capability recovering other detected or suspected being compromised. One key feature our proactive-reactive is that,...

Although a large research effort on web application security has been going for more than decade, the of applications continues to be challenging problem. An important part that problem derives from vulnerable source code, often written in unsafe languages like PHP. Source code static analysis tools are solution find vulnerabilities, but they tend generate false positives, and require considerable programmers manually fix code. We explore use combination methods discover vulnerabilities with...

A blockchain is a distributed ledger in which participants that do not fully trust each other agree on the ledger's content by running consensus algorithm. This technology raising lot of interest both academia and industry, but lack tools to evaluate design implementation decisions may hamper fast progress. To address this issue, paper presents discrete-event simulator flexible enough different implementations. These blockchains can be rapidly modeled simulated extending existing models....

Ineffective data management practices pose serious issues to individuals and companies, e.g., risk of identity theft online exposure. Self-sovereign (SSI) is a new approach that ensures users have full control their personal data. In this work, we alleviate breach user privacy problems by showing how SSI can fit within the context established enterprise access technologies. light recent endeavors, explore use decentralized identifiers, verifiable credentials, blockchains support SSI. We...

Entrepreneurs, enterprises, and governments are using distributed ledger technology (DLT) as a component of complex information systems, therefore interoperability capabilities required. Interoperating DLTs enable network effects synergies, similarly to the rise Internet, it unlocks full potential technology. However, due novelty area, mechanisms (IMs) still not well understood, is studied in silos. Consequently, choosing proper IM for use case challenging. Our article has three...

The application of dependability concepts and techniques to the design secure distributed systems is raising a considerable amount interest in both communities under designation intrusion tolerance. However, practical intrusion-tolerant replicated based on state machine approach (SMA) can handle at most f Byzantine components out total n = 3f + 1, which maximum resilience asynchronous systems. This paper extends normal system with special oracle called TTCB. Using this extended we manage...

Journal Article From Consensus to Atomic Broadcast: Time-Free Byzantine-Resistant Protocols without Signatures Get access Miguel Correia, Correia Faculdade de Ciências da Universidade Lisboa, Campo Grande, 1749-016 Portugal *Corresponding author: mpc@di.fc.ul.pt Search for other works by this author on: Oxford Academic Google Scholar Nuno Ferreira Neves, Neves Paulo Veríssimo The Computer Journal, Volume 49, Issue 1, January 2006, Pages 82–96, https://doi.org/10.1093/comjnl/bxh145 Published:...

Web application security is an important problem in today's internet. A major cause of this status that many programmers do not have adequate knowledge about secure coding, so they leave applications with vulnerabilities. An approach to solve use source code static analysis find these bugs, but tools are known report false positives make hard the task correcting application. This paper explores a hybrid methods detect vulnerabilities less positives. After initial step uses taint flag...

Consensus is a classical distributed systems problem with both theoretical and practical interest. Asynchronous Byzantine consensus currently at the core of some solutions for implementation highly-resilient computing services. This paper surveys in message-passing systems, by presenting main results area, classes algorithms discussing important issues like performance resilience these algorithms.

The state of web security remains troubling as applications continue to be favorite targets hackers. Static analysis tools are important mechanisms for programmers deal with this problem they search vulnerabilities automatically in the application source code, allowing remove them. However, developing these requires explicitly coding knowledge about how discover each kind vulnerability. This paper presents a new approach which static learn detect using machine learning. uses sequence model...

The tuple space coordination model is one of the most interesting models for open distributed systems due to its and time decoupling synchronization power. Several works have tried improve dependability spaces through use replication fault tolerance access control security. However, many practical applications in Internet require both This paper describes design implementation DepSpace, a Byzantine fault-tolerant service that provides abstraction. offered by DepSpace secure, reliable...

Critical infrastructures such as the power grid are essentially physical processes controlled by computers connected networks. They're usually vulnerable any other interconnected computer system, but their failure has a high socioeconomic impact. The Utility Infrastructural Resilience (Crutial) project designed an information switch (CIS) to protect these infrastructures. These devices help ensure that incoming and outgoing traffic satisfies security policy of infrastructure in face...

The popularity of wide-area computer services has generated a compelling need for efficient algorithms that provide high reliability. Byzantine fault-tolerant (BFT) can be used with this purpose because they allow replicated systems to continue correct service even when some their replicas fail arbitrarily, either accidentally or due malicious faults. Current BFT perform well on LANs but the are distributed geographically performance is affected by lower bandwidth and higher more...