BTC Exam 1 Questions

What are the 2 main design goals that the Spass system Model tackles?

1) System should be implemented without the need of a trusted third party 2) System should be resilient against malicious helpers.

What are three advantages of applying blockchain to RPMs?

1) They provide robustness against failure and data exposure. 2) They provide data security and privacy. 3) They provide a way of proving that information sent/received has not been modified.

What is FairShare? Explain its uses/advantages?

FairShare is a fair, accountable, and secure data sharing scheme. Some of its uses are mentioned below: 1) It applies proxy re-encryption to ensure security and privacy of data exchanged. 2) Prevents fraudulent activities and resolves disputes amongst parties 3) Establishes provable security guarantees even when participatying parties collide with one another.

List and define the three main characteristics of embedded systems that distinguish such systems from other computing systems.

Single Functioned, Tightly-Constrained, and Reactive/Real-Time

List a pair of design metrics that may compete with one another, providing an intuitive explanation of the reason behind the competition.

Size vs Performance. A larger size allows more performance, but if a size gets too large it may be too big for an embedded system.

What is the 'Trinity' and how does it help mobile device blockchain operations?

The 'Trinity' concept couples together Proof-of-Work, Proof-of-Stake, and Proof-of-Activity blockchain strategies to involve mobile devices in the new block generation process.

What is the purpose of auditing? Doesn't blockchain already have a "ledger"?

The audit system adds traceability (forwards and backwards) of server suppliers, as well as validation of off-chain data/processes.

What is the major challenge of the traditional IoT access control models?

The fact that validation and accessing rights pass through a centralized entity, which is prone to a single point of failure.

1What three functions do smart contracts contribute towards in the proposed scheme?

The implement three key chains: the Identity chain, reputation chain, and verify chain. The Identity chain stores hash values, reputation chain records the number of transactions lists and calculates the sum reputation value of participants, and the verify chain records voting results and participant's nodes.

Provide 2 reasons why the blockchain technology is considered for addressing some of the security and privacy issues in IoT devices.

1) As a decentralized and immutable technology, it's good in addressing security and privacy issues. 2) It works as a ledger to keep all transactions known to all users. This is great for security.

List and briefly describe three features/characteristics of Smart Contracts.

1) Autonomy: After they are launched and executed, no further contact is needed. 2) Self-Sufficiency: They are self-sufficient in their ability to gather resources 3) Decentralization: They do not subsist on a single centralized server, they are distributed and self-executed across network nodes.

Discuss three challenges for implementing blockchain on smartphones?

1) Blockchain Scalability: a possible bottleneck as blockchains get larger. 2) Interoperability Aspects: enabling the interoperability between different device vendors. 3) Power and Resource limitations: Even though devices are already capable of executing blockchain-related computations, they still may be developed in a very inefficient way.

Briefly discuss the two attacks mentioned in the paper?

1) Capture Sensitive Information from Screen Display: it extracts sensitive information displayed on screen by creating accessibility services. 2) Capture User Input via USB Debugging: The attack application steals information by determining user input of touchscreen events. It's a real time keylogger of sorts.

Discuss three key challenges in the embedded system design process that are unique to embedded systems design as compared to desktop computing.

1) Design limitations: Limited design to the small form factor, low energy needs, and long-term stable performance without maintenance. 2) Launch Phase: Time-to-Market and Time-to-Revenue 3) Security: very prone to malware and ransomware. Can only fit so much security on a small device

List and define the three main processor technologies. What are the benefits of using each of the three different processor technologies?

1) General-purpose: Low time-to-market and NRE costs, high flexiblity 2) Application specific: Some flexibility, good performance, size, and power. 3) Single purpose: Fast, Low Power, Small Size.

What are the limitations of the FairShare Adversarial Model?

1) Overheads are high for larger file sizes beyond 1MB 2) FairShare allows accessing only non-real-time data, it's not good for time-critical IoT applications.

Describe the four transaction types.

1) Store transactions that store data from devices. 2) Access transactions that access cloud storage. 3) Monitor transactions that monitor device information. 4) Genesis transactions that add devices to the network. 5) Remove transactions that remove devices from the network.

What are three reasons that Electronic Medical Records (EMRs) data are not stored directly on Blockchain?

1) To reduce communication overhead, resulting in faster EMR transmission. 2) To prevent illegal and unauthorized use of private medical records. 3) To reduce the load on the block chain, using hash values instead.

What is a Hyperledger Fabric?

A platform for distributed ledger solutions, delivering high degrees of confidentiality, resiliency, flexibility and scalability.

Define deep learning and how the authors leverage it's mechanisms for video streaming.

A server extracts feedback regions from the DNN and sends them back to the camera as feedback. The camera then re-encodes and sends it to the server for more accurate images.

Briefly describe the main threats for mobile Iot devices

Because mobile IoT devices usually join more networks, main threats involve malicious code that attackers have injected into an IoT device to accelerate its spread. It's a large information risk.

Why is it impossible to obtain new privileges through derivations?

Because the capabilities in a frame can only be reduced, and constrains only increased.

How does Distream attribute the workload between cameras and edge?

It uses a video analytics pipeline that partitions based on the workload ratio of the two sides.

What are the main security goals of the cryptocurrency wallets?

Confidentiality to prevent unauthorized access, and Integrity to prevent information from being modified by unauthorized entities.

Discuss three reasons why hardware/software co-design is so challenging?

For testing there's no standard tool that fits all; you need to design custom testing environments. Hardware execution is much slower than software; hardware can takes days to simulate a few cycles. Co-optimization is very difficult even without HW/SW partitioning.

Stateless blockchains today are made mainly for cryptocurrencies, applying this to general applications would introduce several new challenges. In the presentation on SlimChain a few of these challenges involving smart contracts and cryptocurrency exchange were discussed. Describe two of these fundamental challenges.

In general applications, transactions supported by smart contracts may contain arbitrary logic. This demands novel proof techniques to attest to the integrity of off-chain executions. A smart contract transaction would introduce read and write sets of arbitrary size. This is significantly more complex than simple cryptocurrency transactions and requires an extra design to support on-chain commitment updates.

The limitations in blockchain itself are important factors hindering the development of smart contracts. What are the limitations in blockchain?

Irreversible Bugs, Performance Issues, Lack of Trusted Data Feeds (Oracles), and Lack of Standards and Regulations.

What is Two threshold Based Voting Mechanism used for in the Spass Design? What happens to the malicious helpers?

It is an approach for identifying malicious helpers based on data collected at the smart contract in Ethereum. Malicious helpers are classified as such once detected, and unable to participate in smart contracts anymore. Uses hamming distance and vector algebra.

What is the main goal of the Cryptographic Microblock Verification Protocol and what are its requirements?

It is to verify any microblock at any time, and it should be executable at any node.

What does the interdependence of IoT devices refer to?

It refers to the fact that as devices become more and more complex, human involvement becomes less needed, and can implicitly be controlled by other devices.

What are the non-organizational benefits of this system?

It requires a great deal of storage for transactions. This affects performance and scalability of systems. Each supplier in the supply chain has a user interface API, and a set of microservices that can handle some of these tasks off-chain and lower these costs.

How does this healthcare blockchain system enable secure automated remote patient monitoring using smart contracts？

It uses the smart contracts to facilitate secure analysis and management of medical sensors. It records and writes records of all sensor events on the blockchain.

Define Distream and briefly describe how the video analytic system operates.

It's a distributed live video analytics system based on the smart camera-edge cluster architecture. It adaptively balances the workloads across smart cameras and partitions the workloads between cameras and the edge cluster.

What is the use of symmetric keys in the proposed scheme?

It's a pair of keys shared between two parties that can be used to maintain a private information link

1. What is hardware/software co-design?

It's a tradeoff among various design metrics like performance, size, NRE cost, and flexibility.

What are the four main requirements set to the protocol for PoS miner key generation?

Keys can only be used once, Keys should be distributed securely, any user could not generate keys, and keys do not contain any information related to PoS miner secret keys.

What challenges does deploying blockchain applications to mobile devices that act as actual miners face? What has been introduced to address this challenge?

Mainly due to mining process habits i.e, solving the PoW that requires not only computer power but also energy from interacting mobile devices. To address this challenge, the edge of computing paradigm was introduced by the research community for cases of mobile blockchain networks.

What does the ''miner'' do in smart home? What are the benefits of the miner marks the distributed key as invalid by sending a control message to devices to deny the grant permission?

Miners in smart homes are high resource devices that handle all communication within and external to the home. Benefits: Communications between devices are secured with a shared key, and the miner has a list of devices that share data.

How does the system leverage the distributed ledger properties of the blockchain to achieve authenticity and verifiability?

Only authorized entities can access the blockchain for inspection and block verification; each authorized user will also have their own anonymous account that can only be traced by their own discretion.

List one pro and one con for public blockchains. List one pro and one con for private blockchains.

Public: Pro: Any user can join a public network to add and verify data. Con: Tends to be more resource intensive than a private blockchain. Private: Pro: Implement faster mining and validation rates. Con: Is considered less secure then a public blockchain.

Discuss a security challenge in IoT devices and give the method/approach used to address the issue.

Replay attacks allow attackers to intercept a message from the communication medium. They can be avoided by tagging each message with a session ID and component number.

Existing blockchain systems do not scale well. SlimChain attempts to scale blockchains through off-chain storage and parallel processing. What two main methods did SlimChain use to achieve off-chain storage and parallel processing? Briefly describe each.

Sharding for parallel processing, and stateless blockchains for off-chain storage.

1. Describe the basic Operational Mechanism of Smart Contracts?

They generally have a value and a state, and their triggering conditions and corresponding response actions are preset using triggering condition statements such "if-then" statements.

How do the authors of this paper ensure anonymity among the users of blockchain-based IoT health devices in their proposed model?

They use a lightweight privacy-preserving ring signature scheme that is suitable for anonymous transactions by authentic users.

Why is Bitcoin-NG protocol selected to handle macroblocks?

To reduce the latency between the creation of blocks so that each microblock inside each macroblock is created in real time and adds transactions to the blockchain immediately. Upon arrival.

List 5 common design metrics for embedded systems

Unit Cost, NRE Cost, Size, Performance, Power, Flexibility.

Define video streaming, and list the four performance metrics for evaluating the video streaming protocol. Why are these important?

Video streaming is the process of delivering or transmitting audio and video content over the internet in real-time. Accuracy, Bandwidth usage, Average response delay (freshness) (Paper only listed 3!)