Multi-organizational geospatial cloud infrastructures often require data sharing across different hierarchies to support geospatial development, decision-making, and collaborative initiatives. Existing Geospatial data exchange techniques rely on point-to-point communications between siloed GeoServers. As a result, selective data exchange within a large pool of participants is not possible where there may exist untrustworthy parties that can cause harm by illegitimately obtaining or sharing sensitive data. To address such challenges, we propose a reliable open-source permission-based blockchain platform, called GeoBlocks, designed explicitly for geospatial data, which stores and enforces Access Control Lists (ACLs), while an application layer facilitates inbound requests from one GeoServer to another based on the ACL. Access control rights are established through individual agreements between organizations and recorded on the blockchain ledger using smart contract transactions. In addition, GeoBlocks supports a dynamic programmable dispute resolution mechanism based on the ACL rights. We develop and evaluate GeoBlocks with a proof of concept implementation and show that GeoBlocks has minimal latency overhead for query processing under different scenarios.

Multi-cloud environments such as OnApp and Cloudflare have turned the cloud marketplace towards a new horizon where end-users can host applications transparently over different cloud service providers (CSPs) simultaneously by taking the best from each. Existing cloud federations are typically driven by a broker service which provides a trusted interface allowing the participant CSPs and end-users to coordinate. However, such a broker has the limitations of any centralized trusted authority like risk of manipulation, bias, censorship, single point of failure, etc. In this paper, we propose a decentralized trustless cloud federation architecture called CollabCloud which eliminates any central mediator while addressing the challenges introduced by byzantine participants. CollabCloud utilizes blockchain, and introduces a novel interoperability protocol bridging a permissionless blockchain as an open interface for the end-users, and a permissioned blockchain as a coordination platform for the CSPs. We have implemented CollabCloud with Ethereum, Hyperledger Fabric and Burrow platforms. Experiments with a proof-of-concept testbed emulating 3 CSPs show that CollabCloud can operate within an acceptable response latency for resource allocation, while scaling upto 64 parallel requests per second. Scalability analysis over Mininet emulation platform indicates that the platform can scale well with minimal impact on the response latency as the number of participating CSPs increases.

As cryptocurrencies have gained widespread popularity, the security and handling of crypto-assets have become increasingly crucial. Numerous attacks targeting both users and blockchain platforms have led to substantial financial losses. This paper proposes a system for 2 -factor authentication (2FA) for smart contract wallets, providing users with a flexible, secure, and customizable way of managing their crypto assets. The proposed methodology utilizes cryptographic hash functions and hash chains to generate One Time Passwords (OTPs) for authentication, ensuring protection against unauthorized access. The 2FA setup involves a client interacting with a smart contract along with an authenticator and software wallet While using the pblic-private key pair of wallet as the first factor, and OTPs as the second factor. This is done through a two -stage protocol for bootstrapping arid operation execution, and offers a level of security similar to traditional authentication schemes like HOTP. Using a novel pre -commitment scheme we also defend the users from front -running attacks. The implementation of the system is done in the context of public blockchain evaluating the practicality and effectiveness of the 2FA model. We open source our implementation for the Ethereum platform and make it available for the conununity. Furthermore, we analyse the cost incured based on gas consumption, space requirements and payload. In addition we suggest future enhancements for shorter OTP lengths and time based OTPs.

Applications hosted in commercial clouds are typically multi-tier and comprise multiple tightly coupled virtual machines (VMs). Service providers (SPs) cater to the users using VM instances with different configurations and pricing depending on the location of the data center (DC) hosting the VMs. However, selecting VMs to host multi-tier applications is challenging due to the trade-off between cost and quality of service (QoS) depending on the placement of VMs. This paper proposes a multi-cloud broker model called CoMCLOUD to select a sub-optimal VM coalition for multi-tier applications from an SP with minimum coalition pricing and maximum QoS. To strike a trade-off between the cost and QoS, we use an ant-colony-based optimization technique. The overall service selection game is modeled as a first-price sealed-bid auction aimed at maximizing the overall revenue of SPs. Further, as the hosted VMs often face demand spikes, we present a parallel migration strategy to migrate VMs with minimum disruption time. Detailed experiments show that our approach can improve the federation profit up to 23% at the expense of increased latency of approximately 15%, compared to the baselines.

We initiate the study of Private Certifier Intersection (PCI), which allows mutually distrusting parties to establish a trust basis for cross-validation of claims if they have one or more trust authorities (certifiers) in common.This is one of the essential requirements for verifiable presentations in Web 3.0, since it provides additional privacy without compromising on decentralization.A PCI protocol allows two or more parties holding certificates to identify a common set of certifiers while additionally validating the certificates issued by such certifiers, without leaking any information about the certifiers not in the output intersection.In this paper, we formally define the notion of multi-party PCI in the Simplified-UC framework for two different settings depending on whether certificates are required for any of the claims (called PCI-Any) or all of the claims (called PCI-All).We then design and implement two provably secure and practically efficient PCI protocols supporting validation of digital signature-based certificates: a PCI-Any protocol for ECDSAbased certificates and a PCI-All protocol for BLS-based certificates.The technical centerpiece of our proposals is the first secretsharing-based MPC framework supporting efficient computation of elliptic curve-based arithmetic operations, including elliptic curve pairings, in a black-box way.We implement this framework by building on top of the well-known MP-SPDZ library using OpenSSL and RELIC for elliptic curve operations, and use this implementation to benchmark our proposed PCI protocols in the LAN and WAN settings.In an intercontinental WAN setup with parties located in different continents, our protocols execute in less than a minute on input sets of size 40, which demonstrates the practicality of our proposed solutions.

Virtual machine (VM) migration enables cloud service providers (CSPs) to balance workload, perform zero-downtime maintenance, and reduce applications’ power consumption and response time. Migrating a VM consumes energy at the source, destination, and backbone networks, i.e., intermediate routers and switches, especially in a Geo-distributed setting. In this context, we propose a VM migration model called Low Energy Application Workload Migration ( LEAWM ) aimed at reducing the per-bit migration cost in migrating VMs over Geo-distributed clouds. With a Geo-distributed cloud connected through multiple Internet Service Providers (ISPs), we develop an approach to find out the migration path across ISPs leading to the most feasible destination. For this, we use the variation in the electricity price at the ISPs to decide the migration paths. However, reduced power consumption at the expense of higher migration time is intolerable for real-time applications. As finding an optimal relocation is $\mathcal {NP}$ -Hard, we propose an Ant Colony Optimization (ACO) based bi-objective optimization technique to strike a balance between migration delay and migration power. A thorough simulation analysis of the proposed approach shows that the proposed model can reduce the migration time by 25%–30% and electricity cost by approximately 25% compared to the baseline.

The admission process in academic institutions (universities, colleges, etc.) is more digitized than ever. Starting from standardized tests to application processing, to shortlisting on the basis of merit, to even document verification, everything is carried out through online processes now. However, in spite of having huge benefits in terms of convenience, existing admission processes severely lack transparency. The entire process is dependent on certain central authoritative entities such as the testing authorities followed by the institutes themselves. Moreover, critical tasks such as verifying educational and identity-related documents of students is a tedious affair and the effort is duplicated across all institutions. In this work, we attempt to overcome these limitations of the existing workflow of academic institutes' admission process by designing a distributed ledger based framework that involves the academic institutes, testing authorities, document and credential validators, as well as the students. Our framework DeSAT uses verifiable credentials together with a permissioned ledger to remove the duplicate efforts in verification of test scores as well as validation of students' documents. In addition, it makes the entire process transparent and auditable while enforcing fair merit-based seat allotment through smart contracts. Through a prototype implementation using Hyperledger Fabric, Indy, and Aries, we demonstrate the practicality of DeSAT and show that our system offers acceptable performance while scaling with the number of participating institutions.

Interoperation between permissioned consortium blockchain networks relies on their abilities to discover and validate the identities of each others' participant organizations. These organizations may possess self-sovereign decentralized identities and verifiable credentials issued by well-known certification authorities. Two mutually untrusting networks of organizations can establish a basis for interoperation if they have one or more certification authorities in common. Yet, for privacy reasons, neither of them may want to expose a priori their entire lists of authorities, necessitating a negotiation process through which common authorities can be identified. In this paper, we analyze this negotiation problem, and propose and analyze two solution approaches, one involving active participation of the trust anchors and the other without involving them.

Online seat allocation processes such as Joint Seat Allocation Authority in India have streamlined the university seat allocation process and reduced the risk of seats being vacant. Similar centralized online counseling processes are used for many universities in different countries. In-spite of being a collaborative process involving different stakeholders, such systems are centralized having their inherent limitations including lack of transparency, risk of censorship, manipulation, and single point of failure. In this demonstration, we showcase a decentralized ledger technology based system and application for democratizing the university seat allocation process. We demonstrate that the user experience of the proposed system is almost identical to the traditional centralized one, in spite of having the additional benefits of transparency, auditability, and non-repudiability of the decentralized architecture.

With the increasing adoption of private blockchain platforms, consortia operating in various sectors such as trade, finance, logistics, etc., are becoming common. Despite having the benefits of a completely decentralized architecture which supports transparency and distributed control, existing private blockchains limit the data, assets, and processes within its closed boundary, which restricts secure and verifiable service provisioning to the end-consumers. Thus, platforms such as e-commerce with multiple sellers or cloud federation with a collection of cloud service providers cannot be decentralized with the existing blockchain platforms. This paper proposes a decentralized gateway architecture interfacing private blockchain with end-users by leveraging the unique combination of public and private blockchain platforms through interoperation. Through the use case of decentralized cloud federations, we have demonstrated the viability of the solution. Our testbed implementation with Ethereum and Hyperledger Fabric, with three service providers, shows that such consortium can operate within an acceptable response latency while scaling up to 64 parallel requests per second for cloud infrastructure provisioning. Further analysis over the Mininet emulation platform indicates that the platform can scale well with minimal impact over the latency as the number of participating service providers increases.

Interoperation for data sharing between permissioned blockchain networks relies on networks' abilities to independently authenticate requests and validate proofs accompanying the data; these typically contain digital signatures. This requires counterparty networks to know the identities and certification chains of each other's members, establishing a common trust basis rooted in identity. But permissioned networks are ad hoc consortia of existing organizations, whose network affiliations may not be well-known or well-established even though their individual identities are. In this paper, we describe an architecture and set of protocols for distributed identity management across permissioned blockchain networks to establish a trust basis for data sharing. Networks wishing to interoperate can associate with one or more distributed identity registries that maintain credentials on shared ledgers managed by groups of reputed identity providers. A network's participants possess self-sovereign decentralized identities (DIDs) on these registries and can obtain privacy-preserving verifiable membership credentials. During interoperation, networks can securely and dynamically discover each others' latest membership lists and members' credentials. We implement a solution based on Hyperledger Indy and Aries, and demonstrate its viability and usefulness by linking a trade finance network with a trade logistics network, both built on Hyperledger Fabric. We also analyze the extensibility, security, and trustworthiness of our system.

Super cyclone Amphan in May 2020, left the city of Kolkata without cellphone connectivity for hours, and without Internet connectivity for days. Rural areas were much worse affected. After any large-scale natural disaster, this disruption of conventional communication mediums is one of the most significant obstructions for rescue and relief operations. Smartphone messaging apps and social media-based tools depend on the Internet, making them unusable in the golden hour after large scale disasters like cyclones, earthquakes, etc. In such dire situations, to establish an alternate communication mechanism, we propose Aco-Wi, a Messaging application that uses opportunistic acoustic initiated Wi-Fi communication system that can work seamlessly through consumer smartphones. We are designing Aco-Wi keeping in mind the user experience, energy efficiency, and performance. The initial results and user feedback show that the above-mentioned technology is indeed promising.

Serverless computing has gained a significant traction in recent times because of its simplicity of development, deployment and fine-grained billing. However, while implementing complex services comprising databases, file stores, or more than one serverless function, the performance in terms of latency of serving requests often degrades severely. In this work, we analyze different serverless architectures with AWS Lambda services and compare their performance in terms of latency with a traditional virtual machine (VM) based approach. We observe that database access latency in serverless architecture is almost 14 times than that in VM based setup. Further, we introduce some caching strategies which can improve the response time significantly, and compare their performance.

Serverless functions [6, 9, 13, 14], like AWS Lambda [3] or Google Cloud Functions [7], are new techniques for running short-lived workloads over a cloud, which are particularly preferred by users for their easy deployment, fine-grained billing and automatic scaling. Unlike traditional cloud offerings such as VMs and containers, these functions are stateless , where each function execution starts with a fresh state of memory, disk, and other resources. A multi-tenant serverless cloud platform has two primary components, a gateway controlled by the cloud service provider (CSP) and the user functions which are users' programs. A typical serverless function execution is stateless and involves broadly the following steps: (1) User request is received by the gateway, (2) Gateway executes the function and passes the request arguments, (3) The function performs necessary computation, (4) Optionally, it can call other functions through the gateway or access external Database, and (5) It returns the result to the user.

Facebook’s “Mark Yourself Safe” or Google Person Finder are quite popular nowadays. Such applications generate crisis maps based on crowdsourced information during or after disasters. Crisis maps are inevitably an extremely effective digital dashboard application for rescue and reliefs. But what if there is even a partial Internet blackout after the disaster strikes? This is indeed a common scenario, but today’s crisis mapping solutions heavily depend on the Internet. In this paper, we discuss a thorough background study and design details of Soteria, an end-to-end solution for smartphone-based opportunistic crisis mapping in the fate of Internet blackouts. Soteria uses intelligent and energy-efficient mechanisms for opportunistic ad-hoc information collection and filtering along with data summarization and dashboard application for crisis mapping over end-users’ smartphones. The smartphone application intelligently incorporates and tunes the existing network systems and services at the backend to make the system work even when the conventional network infrastructure fails. We evaluate the performance of Soteria from multiple field-trials for over five years, and the observed quantitative and qualitative performance is extremely promising for its mass-scale adoption at the disaster-prone areas.

Modeling the demand and supply during an absolute catastrophe is a major challenge for any disaster manager. This paper demonstrates implementation of an easily deployable end-to-end system, by which, various situational data can be collected by the stakeholders during any post-disaster circumstances, and a general summarized view can be plotted on crisis map. The proposed Four Tier Hybrid Ad hoc Network Architecture does not require an Internet backbone but can conduct the complete process in 'offline' mode. Periodic Merging of GIS data enriches the quality of the summarized view. Here we have tried to evaluate the system based on some initial results on a dummy challenged network scenario.

This paper proposes a virtual machine (VM) migration model to reduce the power consumption while migrating a set of VMs over geo-distributed clouds. We develop an approach to find out the migration path across different Internet Service Providers (ISPs) leading to the most feasible destination. For this, we make use of the variation in the electricity price at the ISPs for deciding the migration paths. However, reduced power consumption at the expense of higher migration time is intolerable for real-time applications. Hence, we propose an Ant Colony Optimization (ACO) based bi-objective optimization technique to strike a balance between the power consumption and the migration time to make the implementation realistic. Thorough simulation analysis of the proposed approach shows that it can achieve low power consumption cost with acceptable migration time.

Online Crisis Mapping Systems (CMS) are de facto tools to facilitate disaster response, although they may fail to work during the initial days of large-scale (Level 3) natural disasters, because of the unavailability of Internet due to the breakdown of existing communication infrastructures and the power-grids. In this paper, we present a novel end-to-end application system, called CRIMP, which can run both as an Android App in users' smartphones as well as an application in custom portable units, referred as Information Storage Boxes (ISB) which are designed as networking building-blocks to combat network-outage after large-scale disasters. In the absence of Internet, it leverages (a) the presence of active smartphone users as crisis mappers, (b) inherent mobility of rescue vehicles as data mules, and (c) presence of few pre-deployed ISBs in a disaster-hit locality. CRIMP creates a Wi-Fi ad-hoc network to opportunistically aggregate captured information, processes it, and finally embeds it on maps to generate semi-real-time ‘Local Crisis Map’ (LCM) in a decentralized way. It considers issues unique to an offline crisis mapping system and implements a channel-sensed, hands-free, scalable, ad-hoc connectivity among devices in proximity for ‘role-based’ seamless syncing of situational messages, addressing the ‘consistency-coverage-quality trade-off’. Extensive lab-scale testing and analysis from some field-level mock drills reveal that CRIMP can speed-up the need assessment and emergency response in time-sensitive situations.

The current implementations of federated clouds depend on a central broker that takes care of the resource allocation as well as scheduling and pricing for the shared resources under the federation. In this paper, we propose an alternate architecture for federated Infrastructure-as-a-service (IaaS) provisioning with the help of a completely decentralized marketplace designed using the blockchain technology. The proposed architecture is free from any central broker and supports decentralization, transparency of resource exchanges, autonomy of service providers, immutability in information exchange for dispute-free billing and fairness for service provisioning. An in-house implementation of the proposed architecture with three cloud service providers shows that CloudChain indeed supports resource allocation fairness while achieving almost similar service provisioning performance compared to a central broker based federation architecture.

Decision making after an emergency like those after a large-scale disaster (natural/man-made) is often impaired due the non-availability of crisis information from field. The key reason behind such hindrance in getting information off the field is due to disruption/breaking of conventional communication channel (manual or automatic) as an outcome of the crisis event. The post-crisis operations like evacuation, rescue-relief are affected at large due to poor decision making and lack of coordination among the field workers and officials in charge of the emergency management and mitigation. This leads to added suffering to the victims, increased death-toll, and mass agitation, anger and mistrust among all the stake-holders. Humanitarian organizations present crisis mapping services for shaping the rescue-relief activities. The crisis mapping systems collects crisis data from online social media, news feeds, etc., and portrays them through an online map server. However, in a situation when network is disrupted, such services become useless. In this work of ours, we would like to present an application that may run on Android-based mobile devices and could prepare 'localized' crisis map through 'offline' crowd-sourcing of situational data and a distributed processing of the collected data in seamless manner. To ensure that the generated localized crisis map hold the most important information, and that it contains information from almost every corner of the affected area, a novel data dissemination strategy is proposed. For better serving the affected community, the resulting crisis data is portrayed on a nice map interface generated locally, whenever possible. In addition to crisis data, mobility trails of other users, whenever available, are embedded on the same interface for the purpose of travel route suggestion for the users in a changing environment after the crisis.