Blockchain Technology Study Guide

Blockchain Technology Study Guide

Quiz

What is the role of a Blockchain Service Provider (BSP) in the context of Volt?

A Blockchain Service Provider (BSP) in Volt is responsible for creating and updating an append-only, tamper-proof ledger. It acts as the centralized entity for the Volt blockchain network, with which member nodes interact to submit transactions and synchronize the ledger.

Describe the structure of the Verifiable Outsourced Ledger (VOL) in Volt.

VOL is an append-only blockchain where each block consists of a metadata block and a data block. The metadata block identifies the Volt network, a hash pointing to the previous block, and a hash of the corresponding data block. The data block stores a list of transactions. Each VOL entry is accompanied by a set of signatures from the BSP, called receipts.

How is Volt's programming model similar to Ethereum's smart contracts?

Volt's programming model is similar to Ethereum's smart contracts, allowing developers to define the behavior of a blockchain network using a blockchain state machine (BSM). The BSM consists of code (Ψc) and internal state (Ψs). Ψc processes transactions, while Ψs stores the state of the blockchain network.

Explain the purpose of "Caesar consensus" in Volt.

Caesar consensus is a distributed protocol used in Volt that enables member nodes to agree on the correctness of a BSP ledger, even if the BSP exhibits arbitrary behavior. It ensures that all honest nodes have a common view of the VOL, even in the face of adversarial behavior.

How do heartbeat transactions work in Volt?

Heartbeat transactions are special transactions that member nodes submit to the VOL. They act as a proof of the node's current view of the ledger. The transaction includes the node ID, the verified VOL height, the hash of the metadata block at that height, and the node's digital signature.

How can member nodes configure different consensus policies in Volt?

Member nodes can configure different consensus policies in Volt by defining the conditions under which a prefix of a VOL is considered submitted. This allows for flexible fault tolerance and consistency models (e.g., Byzantine fault tolerance, crash fault tolerance) based on the risk tolerance and performance requirements of a particular transaction or member node.

What is the significance of BSP accountability in Volt?

BSP accountability is critical to Volt's security because the BSP is an untrusted entity. Accountability mechanisms ensure that if a BSP misbehaves or violates security properties, it can be detected and member nodes can take action.

How do BSPs handle security violations in Volt, such as forks in VOL?

If a BSP commits a security violation (e.g., by creating a fork in VOL) ​​and is detected by honest nodes, the BSP's signature serves as evidence. Member nodes can then use this cryptographically verifiable evidence to hold the BSP accountable and potentially switch to a new BSP.

Describe the key components of Volt's modular BSP design and their functions.

Volt's modular BSP generally consists of four components: a verifiable storage service (provides storage with receipts), a link service (maintains a linear history of blocks), a state transition service (executes blockchain code to process transactions), and a coordinator (coordinates BSP components).

How does Volt achieve state outsourcing while maintaining data confidentiality?

Volt achieves state outsourcing while preserving confidentiality by executing blockchain code in a state transition service using a secure execution environment (e.g., Intel SGX). This setup ensures that sensitive data, including transactions and internal state, remains encrypted and invisible to the BSP or even member nodes.

Paper Questions

Discuss the advantages and disadvantages of Volt compared to traditional permissioned blockchain systems such as Hyperledger Fabric.

Explain how the Caesar consensus protocol addresses the challenge of untrusted BSPs in Volt. Compare and contrast the use of heartbeat transactions with traditional consensus mechanisms.

Analyze how Volt’s modular BSP architecture facilitates security, performance, and outsourceability.

How does Volt ensure confidentiality of sensitive data in blockchain networks? Discuss the techniques it uses and their limitations.

Explore the potential use of Volt as a secure multi-party collaboration (SMC) solution in real-world applications such as supply chain management, healthcare, or digital identity. Discuss its implementation challenges and considerations.

Glossary

Term Definitions Blockchain Service Provider (BSP) A centralized entity in Volt that is responsible for creating and updating an append-only, tamper-proof ledger. Verifiable Outsourced Ledger (VOL)An append-only blockchain data structure used in Volt that stores transactions and other related information.Caesar ConsensusA distributed protocol used in Volt that enables member nodes to agree on the correctness of the BSP ledger.Heartbeat TransactionsSpecial transactions that member nodes submit to the VOL to prove their current view of the ledger.Blockchain State Machine (BSM)The code and state that define the behavior of the blockchain network in Volt.Secure Execution Environment (enclave)Hardware capabilities that provide isolated execution environments for enhanced security and confidentiality.Verifiable StorageA storage system that allows clients to verify the integrity of stored data.Link ServicesComponents responsible for creating and maintaining a linear history of blocks in Volt's modular BSP.State Transition ServicesComponents in Volt's modular BSPs responsible for executing blockchain code to process transactions.Coordinator ServicesComponents responsible for coordinating the different components in Volt's modular BSPs.