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Cryptocurrencies have received a lot of research attention in recent years following the release of the first cryptocurrency Bitcoin. With the rise in cryptocurrency transactions, the need for smart contracts has also increased. Smart contracts, in a nutshell, are digitally executed contracts wherein some parties execute a common goal. The main problem with most of the current smart contracts is that there is no privacy for a party's input to the contract from either the blockchain or the other parties. Our research builds on the Hawk project that provides transaction privacy along with support for smart contracts. However, Hawk relies on a special trusted party known as a manager, which must be trusted not to leak each party's input to the smart contract. In this paper, we present a practical private smart contract protocol that replaces the manager with an MPC protocol such that the function to be executed by the MPC protocol is relatively lightweight, involving little overhead added to the smart contract function, and uses practical sigma protocols and homomorphic commitments to prove to the blockchain that the sum of the incoming balances to the smart contract matches the sum of the outgoing balances., 9 pages, 6 figures, published in IEEE BRAINS'21 Conference Proceedings

In the era of social media and messaging applications, people are becoming increasingly aware of data privacy issues associated with such apps. Major messaging applications are moving towards end-to-end encryption (E2EE) to give their users the privacy they are demanding. However the current security mechanisms employed by different service providers are not unfeigned E2EE implementations, and are blended with many vulnerabilities. In the present scenario, the major part of the E2EE mechanism is controlled by the service provider's servers, and the decryption keys are stored by them in case of backup restoration. These shortcomings diminish the user's confidence in the privacy of their data while using these apps. A public Key infrastructure (PKI) mechanism can be used to circumvent some of these issues, but it comes with high monetary costs, which makes it impossible to roll out for millions of users. The paper proposes a blockchain-based E2EE framework that can mitigate the contemporary vulnerabilities in messaging applications. The user's device generates the public/private key pair during application installation, and asks its mobile network operator (MNO) to issue a digital certificate and store it on the blockchain. A user can fetch a certificate for another user from the chat server and communicate securely with them using a ratchet forward encryption mechanism.

Uniquely identifying individuals across the various networks they interact with on a daily basis remains a challenge for the digital world that we live in, and therefore the development of secure and efficient privacy preserving identity mechanisms has become an important field of research. In addition, the popularity of decentralised decision making networks such as Bitcoin has seen a huge interest in making use of distributed ledger technology to store and securely disseminate end user identity credentials. In this paper we describe a mechanism that allows one to store the COVID-19 vaccination details of individuals on a publicly readable, decentralised, immutable blockchain, and makes use of a two-factor authentication system that employs biometric cryptographic hashing techniques to generate a unique identifier for each user. Our main contribution is the employment of a provably secure input-hiding, locality-sensitive hashing algorithm over an iris extraction technique, that can be used to authenticate users and anonymously locate vaccination records on the blockchain, without leaking any personally identifiable information to the blockchain.

Zero-knowledge proofs have always provided a clear solution when it comes to conveying information from a prover to a verifier or vice versa without revealing essential information about the process. Advancements in zero-knowledge have helped develop proofs which are succinct and provide non-interactive arguments of knowledge along with maintaining the zero-knowledge criteria. zk-SNARKs (Zero knowledge Succinct Non-Interactive Argument of Knowledge) are one such method that outshines itself when it comes to advancement of zero-knowledge proofs. The underlying principle of the Zcash algorithm is such that it delivers a full-fledged ledger-based digital currency with strong privacy guarantees and the root of ensuring privacy lies fully on the construction of a proper zk-SNARK. In this paper we elaborate and construct a concrete zk-SNARK proof from scratch and explain its role in the Zcash algorithm., Comment: 8 pages, 5 figures

Over the past decade, we have witnessed the Internet becoming increasingly centralized in the hands of a small number of giant technology firms, that control many of the most popular applications and the content they host on their platforms. In addition, in the majority of instances today, access to the Internet is usually provided through local internet service providers (ISPs) in each country. Governments in different jurisdictions can exert pressure on these technology firms and ISPs to enforce restrictions on Internet usage by their citizens, such as the blocking access to certain sites and/or content. In this paper, we present a promising new approach to circumventing some of these issues. Our decentralized web (DWeb) proposal makes use of a mesh network to connect community based routers. In addition, objects on the DWeb are indexed using Bblockchain technology, which allows for secure storage of immutable object references, and integrity checking of the data being served to users. Our DWeb design is also capable of operating during network partitions, and is able to quickly re-synchronize with the larger network once connectivity has been restored., 7 pages

5G technology is expected to enable many innovative applications in different verticals. These applications have heterogeneous performance requirements (e.g., high data rate, low latency, high reliability, and high availability). In order to meet these requirements, 5G networks endorse network flexibility through the deployment of new emerging technologies, mainly network slicing and mobile edge computing. This article introduces a distributed blockchain-enabled network slicing (DBNS) framework that enables service and resource providers to dynamically lease resources to ensure high performance for their end-to-end services. The key component of our framework is global service provisioning, which provides admission control for incoming service requests along with dynamic resource assignment by means of a blockchain-based bidding system. The goal is to improve users’ experience with diverse services and reduce providers’ capital and operational expenditure.

The traditional Domain Name System (DNS) does not include any security details, making it vulnerable to a variety of attacks which were discovered in 1990. The Domain Name System Security Extensions (DNSSEC) attempted to address these concerns and extended the DNS protocol to add origin authentication and message integrity whilst remaining backwards compatible. Yet despite the fact that issues with DNS have been well known since the late 90s, there has been very little adoption of DNSSEC. This paper proposes a new system using blockchain technology. Our system aims to provide the same security benefits as DNSSEC whilst addressing the concerns that led to its slow adoption.

The widespread adoption of fax machines in the 1980s revolutionised everyday communications. It was quickly adopted as the standard form of communication across the globe. Since then, the internet has replaced fax as a truly global form of instant communication. However, the fax machine still reigns as the primary form of communication in a number of industries, healthcare being one of them. This paper presents a system that uses a blockchain and an off-chain centralised data storage to give patients and medical professionals instant access to their medical records from anywhere. By assigning each medical record a pseudo anonymous identifier, a second layer "blockchain" for each user can be created allowing for the rapid collection and querying of data. The off-chain pseudo anonymous data storage allows for the data to remain unencrypted enabling the rapid generation of anonymous medical datasets which can be used for machine learning and data mining on the data, potentially bringing many benefits to the healthcare industry.

The SSL protocol has been widely used for verifying digital identities and to secure Internet traffic since the early days of the web. Although X.509 certificates have been in existence for more than two decades, individual user uptake has been low due to the high cost of issuance and maintenance of such certs. This has led to a situation whereby users are able to verify the identity of an organization or e-commerce retailer via their digital certificate, but organizations have to rely on weak username and password combinations to verify the identity of customers registered with their service. We propose the X509Cloud framework which enables organizations to issue certificates to their users at zero cost, and allows them to securely store and disseminate client certificates using the Bitcoin inspired blockchain protocol. This in turn will enable organizations and individuals to authenticate and to securely communicate with other users on the Internet.

This paper introduces a new P2P Electronic Cash system called Net coin. The purpose of Net coin is to facilitate inexpensive peer-to-peer monetary transactions on the Web. Its salient features are that it is a traceable system with an efficient mechanism for verifying transactions. Net coins are reusable and can be easily passed from one user to another. The issuing of virtual currency and verification of transactions are performed by trusted mints, which act as the gateway between the fiat and virtual currency worlds. There is no need to maintain a public ledger, which would inhibit use on a global scale because of rapidly increasing memory and bandwidth requirements. The system is neither inflationary nor deflationary in nature and does not purport a new economic model. As a fiat-backed currency it should not suffer the volatility issues associated with Bit coin. In this paper the two most prominent electronic payment systems of the last forty years, namely Ecash and Bit coin, are examined. Net coin is then introduced in detail and is designed to address the shortcomings of these payment systems.

PUBLISHED, The Mobile IP protocol has evolved from providing mobility support for portable computers to support for wireless handheld devices with high mobility patterns. A new category of micromobility protocols has been proposed to deal with the increased signaling loads that will be generated with large populations of such devices on a network. We argue that the authentication schemes presently employed in these networks do not scale well for large numbers of nodes, and that the lack of accounting procedures prevents the mass deployment of these networks. We envisage that future access networks will he operated by independent service providers, who will charge users for access to services in the fixed network but may not have long-term contractual relationships with them. These access networks may also employ a variety of micromobility protocols for fast handover support. We present a scheme based on hash chains, which allows for fast authentication of datagrams for secure updating of router entries within the access network, and real-time accounting of network usage by mobile nodes. Such a system will alleviate problems of fraud in mobile networks and eliminate the need for interoperator billing agreements.

Identity Based Encryption (IBE) has been constructed from bilinear pairings, lattices and quadratic residuosity. The latter is an attractive basis for an IBE owing to the fact that it is a well-understood hard problem from number theory. Cocks constructed the first such scheme, and subsequent improvements have been made to achieve anonymity and improve space efficiency. However, the anonymous variants of Cocks’ scheme thus far are all less efficient than the original. In this paper, we present a new universally-anonymous IBE scheme based on the quadratic residuosity problem. Our scheme has better performance than the universally anonymous scheme from Ateniese and Gasti (CT-RSA 2009) at the expense of more ciphertext expansion.

We present a flexible approach for achieving user-controlled privacy and integrity of documents that are collaboratively authored within web-based document-editing applications. In this setting, the goal is to provide security without modifying the web application's client-side or server-side components. Instead, communication between both components is transparently intercepted and processed (if necessary) by means of a local proxy or browser plugin. We improve upon existing solutions by securely preserving real-time collaboration for encrypted documents and facilitating self-containment of the metadata (an overhead of encryption) within the same document. An architectural generalization is also presented that permits generic transformations and fine-grained access control. Security is assessed with respect to several threat models, and performance is evaluated alongside other approaches.

PUBLISHED, A mobile ad hoc network is a collection of nodes that are connected through a wireless medium and form rapidly changing topologies. The widely accepted existing routing protocols designed to accommodate the needs of such self-organised networks do not address possible threats aimed at the disruption of the protocol itself. The assumption of a trusted environment is not one that can be realistically expected; hence several efforts have been made towards the design of a secure routing protocol for ad hoc networks. The main problems with this approach are that it requires changes to the underlying routing protocol and that manual configuration of the initial security associations cannot be completely avoided. We propose RIDAN, a novel architecture that uses knowledge-based intrusion detection techniques to detect, in real-time, attacks that an adversary can perform against the routing fabric of a mobile ad hoc network. Our system is designed to take countermeasures minimising the effectiveness of an attack and maintaining the performance of the network within acceptable limits. RIDAN does not introduce any changes to the underlying routing protocol since it operates as an intermediate component between the network traffic and the utilised protocol with minimum processing overhead. We have developed a prototype that was evaluated in AODV-enabled networks using the ns-2 network simulator.

The past few years have witnessed an explosive growth in the use of wireless mobile handheld devices as the enabling technology for accessing Internet-based services, as well as for personal communication needs in ad hoc networking environments. Most studies indicate that it is impossible to utilize strong cryptographic functions for implementing security protocols on handheld devices. Our work refutes this. Specifically, we present a performance analysis focused on three of the most commonly used security protocols for networking applications, namely SSL, S/MIME and IPsec. Our results show that the time taken to perform cryptographic functions is small enough not to significantly impact real-time mobile transactions and that there is no obstacle to the use of quite sophisticated cryptographic protocols on handheld mobile devices.