U ovom radu su istražene osnove tehnologije distribuirane glavne knjige i najpoznatiji algoritmi konsenzusa koji mijenjaju centralni autoritet. Uspored̄ene su njihove prednosti i mane. U nastavku je uvod u Ethereum protokol i njegovu arhitekturu. Objašnjen je način provod̄enja transakcija i izvršavanja programskog koda na Ethereum virtualnom stroju. Najveći dio rada je usmjeren postavljanju privatne Ethereum mreže izmed̄u čvorova raznorodnog sklopovlja. Detaljno je opisan postupak izrade novčanika, provod̄enja transakcija, postavljanja i izvršavanja programskog koda pametnog ugovora na blockchain. Ispitani su zahtjevi procesa zaduženog za sudjelovanje u mreži na svakom čvoru.
Yuichiro Chinen, Naoto Yanai, Jason Paul Cruz, Shingo Okamura
Ethereum smart contracts are programs that are deployed and executed in a consensus-based blockchain managed by a peer-to-peer network. Several re-entrancy attacks that aim to steal Ether, the cryptocurrency used in Ethereum, stored in deployed smart contracts have been found in the recent years. A countermeasure to such attacks is based on dynamic analysis that executes the smart contracts themselves, but it requires the spending of Ether and knowledge of attack patterns for analysis in advance. In this paper, we present a static analysis tool named \textit{RA (Re-entrancy Analyzer)}, a combination of symbolic execution and equivalence checking by a satisfiability modulo theories solver to analyze smart contract vulnerabilities to re-entrancy attacks. In contrast to existing tools, RA supports analysis of inter-contract behaviors by using only the Etherum Virtual Machine bytecodes of target smart contracts, i.e., even without prior knowledge of attack patterns and without spending Ether. Furthermore, RA can verify existence of vulnerabilities to re-entrancy attacks without execution of smart contracts and it does not provide false positives and false negatives. We also present an implementation of RA to evaluate its performance in analyzing the vulnerability of deployed smart contracts to re-entrancy attacks and show that RA can precisely determine which smart contracts are vulnerable.
Durbadal Chattaraj, Sourav Saha, Basudeb Bera, Ashok Kumar Das
Software Defined Networking (SDN) becomes a de facto standard for the future Internet. SDN decouples the control plane from the data plane of a proprietary network asset to ensure better programmability and security for designing more innovative future network applications. Presently, the SDN framework does not have proper access control mechanism among different entities, namely SDN applications, SDN controllers and switches. To achieve this goal, this paper proposes a blockchain-based access control scheme for the SDN framework. The proposed scheme has the capability to resist various well-known attacks and alleviate the existing single point of controller failure issue in SDN.
Stefano Angieri, Marcelo Bagnulo, Alberto García-Martínez, Bingyang Liu · 5 authors
In this paper, we present InBlock4, a blockchain-based alternative to RPKI for the provision of Route Origin validation for BGP. InBlock4 embeds an alternative trust model to protect entities obtaining a resource allocations from errors and abuses from other entities in the allocation hierarchy. InBlock4 is compatible with BGPsec. Moreover, InBlock4 can be bootstrapped using the information in the RPKI and it can coexists with RPKI-based route origin validation. In the paper, we also present a working implementation of InBlock4 for Ethereum and we quantify its performance.
The contemporary IC supply chain depends heavily on third-party intellectual property (3PIP) that is integrated to in-house designs. As the correctness of such 3PIPs should be verified before integration, one important challenge for 3PIP vendors is proving the functionality of their designs while protecting the privacy of circuit implementations. In this work, we present Pythia that employs zero-knowledge proofs to enable vendors convince integrators about the functionality of a circuit without disclosing its netlist. Pythia automatically encodes netlists into zero knowledge-friendly format, evaluates them on different inputs, and proves correctness of outputs. We evaluate Pythia using the ISCAS'85 benchmark suite.
Physical Unclonable Functions (PUFs) and Hardware Security
Integrated Circuits and Semiconductor Failure Analysis
Sajjad Rezaei, Ehsan Khamespanah, Marjan Sirjani, Ali Sedaghatbaf · 5 authors
Blockchain is a shared, distributed ledger on which transactions are digitally recorded and linked together. Smart Contracts are programs running on Blockchain and are used to perform transactions in a distributed environment without need for any trusted third party. Since smart contracts are used to transfer assets between contractual parties, their safety and security are crucial and badly written and insecure contracts may result in catastrophe. Actor-based programming is known to solve several problems in building distributed software systems. Moreover, formal verification is a solid technique for developing dependable systems. In this paper, we show how the actor model can be used for modeling, analysis and synthesis of smart contracts. We propose Smart Rebeca as an extension of the actor-based language Rebeca, and use the model checking toolset Afra for verification of smart contracts. We implement a synthesizer to synthesize Solidity programs that run on the Ethereum platform from Smart Rebeca models. We examine the challenges and opportunities of our approach in modeling, formal verification, and synthesis of smart contracts using actors.
Tyler Thomas, Mathew Piscitelli, Ilya Shavrov, Ibrahim Baggili
We present Memory FORESHADOW: Memory FOREnSics of HArDware cryptOcurrency Wallets. To the best of our knowledge, this is the primary account of cryptocurrency hardware wallet client memory forensics. Our exploratory analysis revealed forensically relevant data in memory including transaction history, extended public keys, passphrases, and unique device identifiers. Data extracted with FORESHADOW can be used to associate a hardware wallet with a computer and allow an observer to deanonymize all past and future transactions due to hierarchical deterministic wallet address derivation. Additionally, our novel visualization framework enabled us to measure both the persistence and integrity of artifacts produced by the Ledger and Trezor hardware wallet clients. The framework can be generalized for use in future memory forensics work.
As blockchain becomes increasingly popular across various industries in recent years, many companies started designing and developing their own smart contract platforms to enable better services on blockchain. While smart contracts are notoriously known to be vulnerable to external attacks, such platform diversity further amplified the security challenge. To mitigate this problem, we designed the very first cross-platform security analyzer called Seraph for smart contracts. Specifically, Seraph enables automated security analysis for different platforms built on two mainstream virtual machine architectures, i.e., EVM and WASM. To this end, Seraph introduces a set of general connector API to abstract interactions between the virtual machine and blockchain, e.g., load and update storage data on blockchain. Moreover, we proposed the symbolic semantic graph to model critical dependencies and decoupled security analysis from contract code as well. Our preliminary evaluation on four existing smart contract platforms demonstrated the potential of Seraph in finding security threats both flexibly and accurately. A video of Seraph is available at https://youtu.be/wxixZkVqUsc.
Tai D. Nguyen, Long Hoang Pham, Jun Sun, Yun Lin · 5 authors
Smart contracts are Turing-complete programs that execute on the infrastructure of the blockchain, which often manage valuable digital assets. Solidity is one of the most popular programming languages for writing smart contracts on the Ethereum platform. Like traditional programs, smart contracts may contain vulnerabilities. Unlike traditional programs, smart contracts cannot be easily patched once they are deployed. It is thus important that smart contracts are tested thoroughly before deployment. In this work, we present an adaptive fuzzer for smart contracts on the Ethereum platform called sFuzz. Compared to existing Solidity fuzzers, sFuzz combines the strategy in the AFL fuzzer and an efficient lightweight multi-objective adaptive strategy targeting those hard-to-cover branches. sFuzz has been applied to more than 4 thousand smart contracts and the experimental results show that (1) sFuzz is efficient, e.g., two orders of magnitude faster than state-of-the-art tools; (2) sFuzz is effective in achieving high code coverage and discovering vulnerabilities; and (3) the different fuzzing strategies in sFuzz complement each other.
Qingze Hum, Wei Jin Tan, Shi Ying Tey, Latasha Lenus · 7 authors
Cryptocurrencies have become very popular in recent years. Thousands of new cryptocurrencies have emerged, proposing new and novel techniques that improve on Bitcoin's core innovation of the blockchain data structure and consensus mechanism. However, cryptocurrencies are a major target for cyber-attacks, as they can be sold on exchanges anonymously and most cryptocurrencies have their codebases publicly available. One particular issue is the prevalence of code clones in cryptocurrencies, which may amplify security threats. If a vulnerability is found in one cryptocurrency, it might be propagated into other cloned cryptocurrencies. In this work, we propose a systematic remedy to this problem, and we propose CoinWatch (CW). Given a reported vulnerability at the input, CW uses the code evolution analysis and a clone detection technique for indication of cryptocurrencies that might be vulnerable. We applied CW on 1094 cryptocurrencies using 4 CVEs and obtained 786 true vulnerabilities present in 384 projects, which were confirmed with developers and successfully reported as CVE extensions.
How someone can get health insurance without sharing his health information? How you can get a loan without disclosing your credit score? There is a method to certify certain attributes of various data, either this is health metrics or finance information, without revealing the data itself or any other kind of personal data. This method is known as zero-knowledge proofs. Zero-Knowledge techniques are mathematical methods used to verify things without sharing or revealing underlying data. Zero-Knowledge protocols have vast applications from simple identity schemes and blockchains to defense research programs and nuclear arms control
Huashan Chen, Marcus Pendleton, Laurent Njilla, Shouhuai Xu
Blockchain technology is believed by many to be a game changer in many application domains. While the first generation of blockchain technology (i.e., Blockchain 1.0) is almost exclusively used for cryptocurrency, the second generation (i.e., Blockchain 2.0), as represented by Ethereum, is an open and decentralized platform enabling a new paradigm of computing—Decentralized Applications (DApps) running on top of blockchains. The rich applications and semantics of DApps inevitably introduce many security vulnerabilities, which have no counterparts in pure cryptocurrency systems like Bitcoin. Since Ethereum is a new, yet complex, system, it is imperative to have a systematic and comprehensive understanding on its security from a holistic perspective, which was previously unavailable in the literature. To the best of our knowledge, the present survey, which can also be used as a tutorial, fills this void. We systematize three aspects of Ethereum systems security: vulnerabilities, attacks, and defenses. We draw insights into vulnerability root causes, attack consequences, and defense capabilities, which shed light on future research directions.
Sidi Mohamed Beillahi, Gabriela Ciocarlie, Michael Emmi, Constantin Enea
While smart contracts have the potential to revolutionize many important applications like banking, trade, and supply-chain, their reliable deployment begs for rigorous formal verification. Since most smart contracts are not annotated with formal specifications, general verification of functional properties is impeded.
Smart contracts on permissionless blockchains are exposed to inherent security risks due to interactions with untrusted entities. Static analyzers are essential for identifying security risks and avoiding millions of dollars worth of damage.
In recent years, many decentralized applications based on blockchain (DApp) have been developed. Some development tools provide testing functions, but only for developers to write unit tests for smart contracts rather than test DApp as a whole. Moreover, due to the difficulty for testers to understand the implementation details of smart contracts, insufficient functional testing causes some DApps not to meet functional design expectations. The inherent complexity of DApp, inconvenient pre-state setting, and not-so-readable logs make DApp testing challenging. In this paper, we propose Kaya, a testing framework for DApps to bridge these gaps. Firstly, Kaya formulate automatically executed test cases that cover both front-end behaviors and back-end logics with simple setting. Secondly, Kaya provides a flexible and convenient way for test engineers to set the blockchain pre-states. Thirdly, Kaya transforms incomprehensible addresses into readable variables for easier comprehension. Besides, to fit the various application environments, we provide both GUI and CLI for test engineers to use Kaya. Our case study and preliminary human study demonstrates the potential of Kaya in helping test engineers to test DApps more easily. A demo video is at https://youtu.be/7DyI_EpVZFw.
Samson Kahsay Gebresilassie, Joseph Rafferty, Philip Morrow, Liming Chen · 6 authors
The growth of Internet use due to the emergence of new paradigms including social media and the Internet of Things (IoT) has presented several challenges. Within the IoT paradigm, there are several domain-specific challenges, among which security is crucial. Billions of devices in the IoT ecosystem have the responsibility of generating, processing, and analyzing large volumes of data. This data may connect with organizations, services, billions of people and other devices. This high level of interconnectivity creates a complex and heterogeneous network which is challenging to adequately secure the IoT system. IoT devices are smart, diverse, portable, interoperable, often autonomous and deployed in distributed topology. Properly managing the identities of these IoT devices plays a critical role in achieving the security of the overall IoT ecosystem. Notably, existing identity management systems fail to satisfy the requirements of identity management for IoT devices. We present a novel solution for IoT devices identity management based on self-sovereign identity and underpinned by proven security offered by distributed ledger technology. This novel approach provides a secure, portable, decentralized, persistent, unique, interoperable, self-owned and self-controlled identity for IoT devices. A Device's identity with all its relationships in the IoT system are securely managed throughout its entire lifecycle.
In public distributed ledger technologies (DLTs), such as Blockchains, nodes can join and leave the network at any time. A major challenge occurs when a new node joining the network wants to retrieve the current state of the ledger. Indeed, that node may receive conflicting information from honest and Byzantine nodes, making it difficult to identify the current state. In this paper, we are interested in protocols that are stateless, i.e., a new joining node should be able to retrieve the current state of the ledger just using a fixed amount of data that characterizes the ledger (such as the genesis block in Bitcoin). We define three variants of stateless DLTs: weak, strong, and probabilistic. Then, we analyze this property for DLTs using different types of consensus.
Confidentiality is an indispensable requirement in financial applications of blockchain technology, and supporting it along with high performance and friendly programmability is technically challenging. In this paper, we present a system design called CONFIDE to support on-chain confidentiality by leveraging Trust Execution Environment (TEE). CONFIDE's secure data transmission protocol and data encryption protocol, together with a highly efficient virtual machine run in TEE, guarantee the confidentiality in the life cycle of a transaction from end to end. CONFIDE proposes a secure data model along with an application-driven secure protocol to guarantee data confidentiality and integrity. Its smart contract language extension offers users the flexibility to define complex confidentiality models. CONFIDE is implemented as a plugin module to Antfin Blockchain's proprietary platform, and can be plugged into other blockchain platforms as well with its universal interface design. Nowadays, CONFIDE is supporting millions of commercial transactions daily on consortium blockchain running financial applications including supply chain finance, ABS, commodity provenance, and cold-chain logistics.
Proof-of-Work~(PoW) based blockchains typically allocate only a tiny fraction (e.g., less than 1% for Ethereum) of the average interarrival time~($\mathbb{I}$) between blocks for validating transactions. A trivial increase in validation time~($τ$) introduces the popularly known Verifier's Dilemma, and as we demonstrate, causes more forking and increases unfairness. Large $τ$ also reduces the tolerance for safety against a Byzantine adversary. Solutions that offload validation to a set of non-chain nodes (a.k.a. off-chain approaches) suffer from trust issues that are non-trivial to resolve. In this paper, we present Tuxedo, the first on-chain protocol to theoretically scale $τ/\mathbb{I} \approx 1$ in PoW blockchains. The key innovation in Tuxedo is to separate the consensus on the ordering of transactions from their execution. We achieve this by allowing miners to delay validation of transactions in a block by up to $ζ$ blocks, where $ζ$ is a system parameter. We perform security analysis of Tuxedo considering all possible adversarial strategies in a synchronous network with end-to-end delay $Δ$ and demonstrate that Tuxedo achieves security equivalent to known results for longest chain PoW Nakamoto consensus. Additionally, we also suggest a principled approach for practical choices of parameter $ζ$ as per the application requirement. Our prototype implementation of Tuxedo atop Ethereum demonstrates that it can scale $τ$ without suffering the harmful effects of naive scaling in existing blockchains.
Security attacks targeting smart contracts have been on the rise, which have led to financial loss and erosion of trust. Therefore, it is important to enable developers to discover security vulnerabilities in smart contracts before deployment. A number of static analysis tools have been developed for finding security bugs in smart contracts. However, despite the numerous bug-finding tools, there is no systematic approach to evaluate the proposed tools and gauge their effectiveness. This paper proposes SolidiFI, an automated and systematic approach for evaluating smart contracts’ static analysis tools. SolidiFI is based on injecting bugs (i.e., code defects) into all potential locations in a smart contract to introduce targeted security vulnerabilities. SolidiFI then checks the generated buggy contract using the static analysis tools, and identifies the bugs that the tools are unable to detect (false-negatives) along with identifying the bugs reported as false-positives. SolidiFI is used to evaluate six widely-used static analysis tools, namely, Oyente, Securify, Mythril, SmartCheck, Manticore and Slither, using a set of 50 contracts injected by 9369 distinct bugs. It finds several instances of bugs that are not detected by the evaluated tools despite their claims of being able to detect such bugs, and all the tools report many false positives.
Degree verification is the process of verifying the academic credentials of successfully graduated students. It is a time-consuming and costly process as universities annually spend millions of dollars on handling the degree verification requests. Hence, there is a dire need to improve the degree verification process, and the Massachusetts Institute of Technology, Cambridge, MA, USA, has introduced the blockcerts, a blockchain-based solution for freely handling the degree verification requests. Although blockcerts eliminates the cost of the degree verification process, it also alters the existing workflow of degree issuance. This is because blockcerts are primarily focused on facilitating the students, and there is room for improvement from the perspective of educational institutes. In this article, we have introduced the docschain to tackle the three mentioned limitations of the blockcerts. Docschain seamlessly incorporates within the existing workflow of degree issuance by operating over the hard copies of the degree documents. This is achieved through optical character recognition (OCR), and the record of each degree document is stored along with the details of the corresponding OCR template to understand the semantics of the data stored at different sections of the degree document. In contrast to blockcerts, docschain also supports the bulk submission of degree details for both the previously and newly graduated students.
Recently emerging Decentralized Finance (DeFi) takes the promise of cryptocurrencies a step further, leveraging their decentralized networks to transform traditional financial products into trustless and transparent protocols that run without intermediaries. However, these protocols often require critical external information, like currency or commodity exchange rates, and in this respect they rely on special oracle nodes. In this paper, we present a comprehensive measurement study of DeFi price oracles deployed in practice. First, we investigate designs of mainstream DeFi platforms that rely on data from oracles. We find that these designs, surprisingly, position oracles as trusted parties with no or low accountability. Then, we present results of large-scale measurements of deployed oracles. We find and report that prices reported by oracles regularly deviate from current exchange rates, oracles are not free from operational issues, and their reports include anomalies. Finally, we compare the oracle designs and propose potential improvements.