Abstract STARK is a widely used transparent proof system that uses low-degree tests for proving the correctness of a computer program. STARK consumes an intermediate representation known as AIR that is more appropriate for programs with a relatively short and structured description. However, an AIR is not able to succinctly express non-equality constraints, leading to the incorporation of unwanted polynomials. We present the eSTARK protocol, a new probabilistic proof that generalizes the STARK family through the introduction of a more generic intermediate representation called eAIR. We describe eSTARK in the polynomial IOP model, which combines the optimized version of the STARK protocol with the incorporation of three arguments into the protocol. We also explain various techniques that enhance the vanilla STARK complexity, including optimizations applied to polynomial computations, and analyze the tradeoffs between controlling the constraint degree either at the representation of the AIR or inside the eSTARK itself.

Like most modern blockchain networks, Ethereum has relied on economic incentives to promote honest participation in the chain's consensus. The distributed character of the platform, together with the “randomness” or “luck” factor that both proof of work (PoW) and proof of stake (PoS) provide when electing the next block proposer, pushed the industry to model and improve the reward system of the system. With several improvements to predict PoW block proposal rewards and to maximize the extractable rewards of the same ones, the ultimate Ethereum's transition to PoS applied in the Paris Hard-Fork, more generally known as “The Merge”, has meant a significant modification on the reward system in the platform. In this paper, we aim to break down both theoretically and empirically the new reward system in this post-merge era. We present a highly detailed description of the different rewards and their share among validators' rewards. Ultimately, we offer a study that uses the presented reward model to analyze the performance of the network during this transition.

A zero-knowledge (ZK) proof guarantees that the result of a computation is correct while keeping part of the computation details private. Some ZK proofs are tiny and can be verified in short time, which makes them one of the most promising technologies for solving two key aspects: the challenge of enabling privacy to public and transparent distributed ledgers and enhancing their scalability limitations. Most practical ZK systems require the computation to be expressed as an arithmetic circuit that is encoded as a set of equations called rank-1 constraint system (R1CS). In this paper, we presentCircom, a programming language and a compiler for designing arithmetic circuits that are compiled to R1CS. More precisely, withCircom, programmers can design arithmetic circuits at a constraint level, and the compiler outputs a file with the R1CS description, and WebAssembly andC++programs to efficiently compute all values of the circuit. We also provide an open-source library calledcircomlibwith multiple circuit templates.Circomcan be complemented withsnarkjs, a library for generating and validating ZK proofs from R1CS. Altogether, our software tools abstract the complexity of ZK proving mechanisms and provide a unique and friendly interface to model low-level descriptions of arithmetic circuits.

Many peer-to-peer (p2p) overlays require certain security services which could be provided through a Public Key Infrastructure. However, these infrastructures are bound up with a revocation system, such as Certificate Revocation Lists (CRLs). A system with a client/server structure, where a Certificate Authority plays a role of a central server, is prone to suffer from common problems of a single point of failure. If only one Authority has to distribute the whole CRL to all users, perhaps several millions in a structured p2p overlay, a bottleneck problem appears. Moreover, in these networks, users often have a set of pseudonyms that are bound to a certificate, which gives rise to two additional issues: issuing the CRL and assuring its freshness. On the one hand, the list size grows exponentially with the number of network users. On the other hand, these lists must be updated more frequently; otherwise the revocation data will not be fresh enough. To solve these problems, we propose a new distributed revocation system for the Kademlia network. Our system distributes CRLs using the overlay itself and, to not compromise the storage of nodes, lists are divided into segments. This mechanism improves the accessibility, increases the availability and guarantees the freshness of the revocation data.

ABSTRACT Peer‐to‐peer (P2P) overlay networks have been proposed to solve routing problems of big distributed infrastructures, even for Internet scale. But the research community has been questioning the security of these networks for years. Most prior work in security services was focused on trust and reputation systems, anonymity, and secure routing. However, the proper management of identities in overlays is an important prerequisite to provide most of these security services. In this paper, we propose a protocol to control the access to a P2P overlay and to assign identities in a secure way; all this preserving the anonymity of users. This protocol involves two trusted third parties (TTPs), thanks to which it is possible to preserve the users’ anonymity within the network without losing traceability. Users are authenticated by a TTP using real‐world digital certificates, they select their network identifier jointly with the other TTP, and finally, the two TTPs issue the internal certificate to them. The protocol also provides revocability and protection against Sybil attacks, Eclipse attacks, whitewashers, and so on. A detailed protocol description is presented, and a performance and security analysis of the protocol is also provided. Copyright © 2014 John Wiley & Sons, Ltd.

Vehicular Ad Hoc Networks (VANETs) require some mechanism to authenticate messages, identify valid vehicles, and remove misbehaving ones. A Public Key Infrastructure (PKI) can provide this functionality using digital certificates. In PKI, key management and corresponding issuance and revocation of digital certificates is one of the key issues that have to be solved. The IEEE 1609.2 standard states that VANETs will rely on the use of certificate revocation lists (CRLs) to achieve revocation. In this paper, we analyze the problems of using CRLs in these type of networks. Moreover, we describe the Risk Aware Revocation (RAR) mechanism that improves the traditional use of CRLs. RAR takes advantage of the two distinct channel types in VANETs to increase the freshness of the revocation information. Moreover, RAR allows users to gauge the risk of operating in a VANET when using CRLs.

One of the hardest tasks of a public key infrastructure (PKI) is to manage revocation. New communication paradigms push the revocation system to the limit and an accurate resource assessment is necessary before implementing a particular revocation distribution system. In this context, a precise modeling of certificate revocation is necessary. In this paper, we analyze empirical data from real certification authorities (CAs) to develop an accurate and rigorous model for certificate revocation. One of the key findings of our analysis is that the certificate revocation process is statistically self-similar. The proposed model is based on an autoregressive fractionally integrated moving average (ARFIMA) process. Then, using this model, we show how to build a synthetic revocation generator that can be used in simulations for resource assessment. Finally, we also show that our model produces synthetic revocation traces that are indistinguishable for practical purposes from those corresponding to actual revocations.

Abstract Mobile agents are software entities consisting of code, data, and state that can migrate autonomously from host to host executing their code. In such scenario there are some security issues that must be considered. In particular, this paper deals with the protection of mobile agents against manipulation attacks performed by the host, which is one of the main security issues to solve in mobile agent systems. This paper introduces an infrastructure for mobile agent watermarking (MAW). MAW is a lightweight approach that can efficiently detect manipulation attacks performed by potentially malicious hosts that might seek to subvert the normal agent operation. MAW is the first proposal in the literature that adapts software watermarks to verify the execution integrity of an agent. The second contribution of this paper is a technique to punish a malicious host that performed a manipulation attack by using a trusted third party (TTP) called host revocation authority (HoRA). A proof‐of‐concept has also been developed and we present some performance evaluation results that demonstrate the usability of the proposed mechanisms. Copyright © 2010 John Wiley & Sons, Ltd.

Peer-to-peer systems consist of groups of nodes acting as clients and servers. These groups of nodes communicate directly among themselves through wide-area networks. Some of the benefits of fully distributed peer-to-peer systems are scalability, resource aggregation and interoperability without any administration cost or centralized infrastructure support. In this context, reputation schemes aid the service requesters to choose the proper resource provider and to prevent malicious behaviors. This paper analyzes reputation management in fully distributed peer-to-peer systems. This paper discusses the main issues that a reputation framework must address and analyzes the most representative distributed reputation systems. This paper also discusses the main advantages and drawbacks of each proposal in relation to peer-to-peer reputation system requirements

Mobile agents are software entities consisting of code, data and state that can migrate autonomously from host to host performing some actions on behalf of a user. Unfortunately, security issues restrict the use of mobile agents, despite the benefits. The protection of mobile agents against the attacks of malicious hosts is considered the most difficult security problem to solve in mobile agent systems. Previously, the mobile agent watermarking approach (MAW) was presented as a new attack detection technique to aid solving the problem of malicious hosts. That approach was based on embedding a fixed watermark into the mobile agent. Some improvements are now introduced to MAW. Instead of a fixed watermark, the origin host embeds a watermark that can change dynamically during execution. In each host, the marked code creates a data container where the watermark is transferred and the results are hidden. When the agent returns home, the origin host verifies the execution integrity by applying a set of integrity rules to the containers. The paper also explains how MAW can be used to punish malicious hosts by using a trusted third party, the host revocation authority.

Motivation for DARPA's ACS program will be presented along with original goals and objectives of the program. A brief description of some of the efforts that were initiated and why. A report card of what I think the program did well, and where I feel additional work is still required.

In the past, government agencies played pivotal roles in the development of new technologies. For example, Internet is an outgrowth of the ARPAnet project sponsored by the Defense Advanced Research Projects Agency (DARPA) of the United States government. Recently, consortia of private industries, often in cooperation with government agencies, have entered into this picture. As a consequence, researchers in academia have shifted their attentions much more towards real-world applications. In the panel discussion, we first compare the traditional roles of funding agencies in the USA, EU, and Asia. We then focus on the new trends in this funding business in each of the three regions. We will examine why and how such shifts have been made and discuss the roles of funding agencies to be played in the coming years. In particular, we will attempt to search for future roles and new forms/ways of the funding agencies from the viewpoint of economic development driven by technology advancement.

The Adaptive Computing Systems (ACS) program was initiated by Defense Advanced Research Projects Agency (DARPA) of the United States in 1996. With the advent of FPGAs, has emerged a new class of computing systems that contain configurable hardware. This session begins by a presentation by the first ACS program manager of its motivation, original goals, and objectives. It is then followed by presentations of four specific projects under the ACS program. Future activities surrounding the ACS community will be discussed at the end.

Mobile agents are software entities consisting of code and data that can migrate autonomously from host to host executing their code. Despite its benefits, security issues strongly restrict the use of code mobility. The protection of mobile agents against the attacks of malicious hosts is considered the most difficult security problem to solve in mobile agent systems. In O. Esparza et al. [2003] the authors introduced the idea of limiting the execution time in the hosts. Malicious hosts need time to analyze and modify an agent in order to take some profit. Controlling the execution time in the hosts permits detecting manipulation attacks performed by malicious hosts during the agents' execution. This paper presents a protocol for detecting malicious hosts based on the idea of execution time limiting.

Public key cryptography is widely used to provide the security services necessary to develop WEB applications. The PKI is the infrastructure that supports the public key cryptography and the revocation of certificate implies one of its major costs. The authors have developed a revocation system based on the data structures proposed by Naor and Nissim in their authenticated dictionary (AD). Our implementation is called ADMHT and in this paper we address some open issues that are necessary to implement such a system.