CBSA Sample Questions Answers

Contracts can call other contracts or send Ether to non-contract accounts by the means of message calls. Message calls are similar to transactions, in that they have a source, a target, data payload, Ether, gas and return data. In fact, every transaction consists of a top-level message call which in turn can create further message calls.

LTC is Litecoin and is a crypto. Check Ethereum tokens here: https://etherscan.io/tokens

Smart contracts generally are not legal contracts. However, its possible that a smart contract could be accepted as a legal contract but not normally.

Stream cipher basically means using a fixed key which replaces the message with a pseudorandom string of characters. It is basically the encryption of each letter one at a time.

Javascript is the language that Solidity is using to build on the Ethereum Virtual Machine

ASICS are generally used in blockchains such as BTC that have a Proof of Work consensus due to competition

2.0 Ethereum came after Bitcoin. Vitalik Buterin, one of the writers for Bitcoin Magazine that tried to popularize the technology in the early 2012. He witnessed first-hand the problems in the Bitcoin implementation like wasteful mining hardware, centralized mining community, and lack of network scalability. In 2013, the then 19 year old Vitalik described his vision for Ethereum by extending the concept of Bitcoin beyond just currency. He proposed a platform where developer community and entrepreneurs to build distributed application (Dapps) for the Blockchain network. He referred to this concept of trust beyond just currency as ‘smart contracts’ or even blockchain-based “decentralized autonomous organizations” (DAOs).

Truffle is a development environment, testing framework and asset pipeline for Ethereum, aiming to make life as an Ethereum developer easier.

Blockchain 1.0, Grandpa Bitcoin

Asymmetric cryptography utilizes two different keys, a public key and a private to encrypt and decrypt a particular data. The use of one key cancels out the use of the other.

Smart contracts generally are not legal contracts. However, its possible that a smart contract could be accepted as a legal contract but not normally. Read more about Smart contracts here

Endorsing Peers (Endorsers) An endorser executes and endorses transactions. The endorsing peers take the role of endorsing transactions before they are ordered and committed as per the policy defined in Chaincode.

Metamask is essentially a bridge.

Ripple is a real-time gross settlement system (RTGS), currency exchange and remittance network by Ripple.

The Scrypt hash function was initially implemented by the Litecoin development team to avoid what are known, ASICs, from being able mine its cryptocurrency. When mining for cryptocurrencies, users typically have an option between: a CPU, GPU or ASIC miner.

Permissionless - anyone can join Anyone can run a node, run mining software/hardware, access a wallet and write data onto and transact within the blockchain (as long as they follow the rules of the bitcoin blockchain). There is no way to censor anyone, ever, on the permissionless bitcoin blockchain.

To write smart contracts there are a few different languages: Solidity, which is like JavaScript and has .sol as a file extension, Serpent, Python-like with extension .se, and a 3rd, LLL, based on Lisp. Serpent was popular a while back but Solidity is the most popular right now and more robust, so just use Solidity. You prefer Python? Use Solidity.

XOR or “Exclusive OR” is a logic gate.

In Hyperledger, all Nodes are NOT equal. There are three distinct types of nodes: 1. Client Node: That initiates the transaction 2. Peer Nodes: Commits Transaction & keeps the data in sync across the ledger 3. Ordered: They are the communication backbones and responsible for the distribution of the transactions

BFT is notably implemented by Ripple (where validators are pre-selected by the Ripple foundation) and Stellar (where anyone can be a validator and trust is established by the community). BFT is advantageous because it presents scalability and low cost transactions, but like DPoS introduces a component of centralization.

Assets in Hyperledger Fabric are represented in JSON or Binary. Assets are represented in Hyperledger Fabric as a collection of key-value pairs, with state changes recorded as transactions on a Channel ledger. Assets can be represented in binary and/or JSON form.

If you send a transaction to the network, then one miner-node will at some point pick it up. The Miner will run the transaction and add the result to the next block. Now, this doesn’t imply consensus yet. By design all nodes don’t trust each other. Each node must verify that the transaction the miner added to the block is really valid. This means, consensus is reached by having every node running the same transactions again and verifying that the result is correct. Plus, the results are verified in a cryptographic manner.

The Ethereum Virtual Machine (EVM) is the runtime environment for smart contracts in Ethereum. It is not only sandboxed, but actually completely isolated, which means that code running inside the EVM has no access to network, filesystem, or other processes. Smart contracts even have limited access to other smart contracts.

At the time of writing these lines, the Ethereum Blockchain still runs on Proof of Work. When a block is mined, the miner node selects some transactions from a pool of pending transactions. Usually they are sorted by how much gas they would bring in. These transactions are executed and incorporated in the new block. But a block also contains two very important parameters: a difficulty and a timestamp. The difficulty regulates how hard it is to find a block by the miner. The mining time is set to be between 10 and 20 seconds. If it’s beyond 20 seconds, the difficulty is too high and will be automatically lowered going forward. If the mining happens below 10 seconds, then the difficulty increases. The timestamp is the time when a miner found the block. It is not automatically derived, rather it is set by the miner itself and can thus be influenced to a certain degree. The timestamp does not depend on the time zone, as it’s the standard Unix timestamp.

Ether Foundation of all ERC tokens “Smart Money”, money which can be programmed to make decisions for itself

Hyperledger Composer is an open-source application development framework which simplifies the creation of Hyperledger Fabric blockchain applications, thus reducing the time and complexity of development. The tool aims at helping users to create blockchain applications based on Hyperledger Fabric without needing to know the low-level (Go Programming) details involved in blockchain networks.

The main disadvantages are huge expenditures, “uselessness” of computations and 51 percent attack.

Composer Modeling Language is an object-oriented modeling language that defines the domain model for a business network definition. The modeling language is saved as a .cto file.

The merkle tree does not contain a list of all the transactions, rather a hash (digital fingerprint) of all transactions as a tree structure.

Chaincode is a decentralized transactional program, running on the validating nodes. As with every chaincode, it implements the Chaincode interface in particular, Init and Invoke functions. Init is called during Instantiate transaction after the chaincode container has been established for the first time, allowing the chaincode to initialize its internal data. Invoke is called to update or query the ledger in a proposal transaction. Updated state variables are not committed to the ledger until the transaction is committed.

To write smart contracts there are a few different languages: Solidity, which is like JavaScript and has .sol as a file extension, Serpent, Python-like with extension .se, and a 3rd, LLL, based on Lisp. Serpent was popular a while back but Solidity is the most popular right now and more robust, so just use Solidity. You prefer Python? Use Solidity.

Docker provides a secured, lightweight method to sandbox chaincode execution that is "locked down" Chaincode Services uses Docker to host (deploy) the chaincode without relying on any virtual machine or computer language. Docker provides a secured, lightweight method to sandbox chaincode execution. The environment is a "locked down" and secured container, along with a set of signed base images containing secure OS and chaincode language, runtime and SDK images for Golang Additional programming languages can be enabled