Certified Blockchain Developer Ethereum Flashcards by Marie Floury

What is a sandbox?

A test environment that isolates untested code changes and experimentation from the production environment.

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Name 4 characteristics of the EVM

1) Sandboxed VM
2) Runs on every node
3) Turing complete
4) Transaction based state machine

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The blockchain is ………………. which means: The same input will always produce the same output.

Deterministic

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What does hashing do with regards to hash size?

Map data of an arbitrary size to data of a fixed size.

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Which hash function does Ethereum use?

Keccak-256 (which is like SHA256, but the two are NOT interchangeable)

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List in order from lowest to highest the Ether denominations (up to one Ether)

Wei
Kwai (Ada, Femtoether)
Mwei (Babbage, picoether)
Gwei (Shannon, nanoether, nano)
Szabo (microether, micro)
Finney (milliether, milli)

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Kwei is also known as ………………. and ………………..

Ada

Femtoether

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Mwei is also known as ……………… and ………………..

Babbage

Picoether

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Gwei is also known as ………………. and ……………….

Shannon
Nanoether
Nano

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What do you call 1000 ETH?

Kether
Grand
Einstein

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What do you call 1 million ETH

Mether

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What do you call a billion ETH?

Gether

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What do you call a trillion ETH?

Tether

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An ethereum address is bound to a ………………….

Private key

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Describe an Ethereum address

64 character
32 bit hex value.

It is bound to the private key.

The public key is derived from the private key
The address is derived from the public key

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What are the defining characteristics of POW?

mathematical riddle.
resource intensive
The input parameters for a hashed value has to be found
brute force, continuously hashing until the solution is found
Anyone can be a miner

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What are the characteristics of POS?

There is no mining
Uses few resources
Stakeholders lock-in some money and are picked in a semi-random way to forge a new block
Anyone can be a forger

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What is “stake” in the crypto world?

The cryptocurrency a user owns and pledges in order to partake in validation (POS)

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How do Proof-of-Stake algorithms achieve consensus?

By requiring users to stake an amount of their tokens so as to have a chance of being selected to validate blocks of transactions, and get rewarded for doing so.

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What is the incentive for good behaviour in a POS?

Payout in the form of transaction fees (as opposed to freshly created currency in PoW systems)

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Name two types of account in the Ethereum network.

1) Externally owned accounts (EOS’s)

2) Smart contracts

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An EOA is controlled by a ………………..

Private key (owned by an individual)

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A Smart Contract has an …………….. of its own

Address

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To send a transaction, which fields have to be set?

Nonce
Gasprice
Startprice 
To
Value
Data
v,r,s

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What is a replay attack?

A form of network attack in which a valid data transmission is maliciously or fraudulently repeated or delayed.

What is a nonce?

Nonce is a randomly-generated, cryptographic token that is used to prevent replay attacks. In Ethereum, every transaction has a nonce. It is the number of transactions sent from a given address. In cryptography is a one-time code selected in a random or pseudo-random manner that is used to securely transmit the main password, preventing a replay attack Each time you send a transaction, the nonce increases by 1.

What is the notation for wei?

10^18

What is the notation for kwei?

10^15

What is the notation for mwei?

10^12

What is the notation for gwei?

10^9

What is the notation for szabo?

10^6

What is the notation for finney?

10^3

What is the notation for kether?

10^-3

What is the notation for mether?

10^-6

What is the notation for gether?

10^-9

What is the notation for tether?

10^-12

What are private keys for?

To sign transactions. | To derive the public key from (and also the address)

Geth is an Ethereum ................

client

What are opcodes?

The low level human readable instructions of the program. All opcodes have their hexadecimal counterparts, eg “MSTORE” is “0x52”, SSTORE” is “0x55"

What is Dagger Hashimoto and what superseded it?

It is an implementation and specification for the mining algorithm. Ethash superseded it.

Name the two popular Ethereum protocols

1) Go-Ethereum (aka Geth) - written in GO | 2) Parity - written in Rust

How do Ethereum nodes communicate with each other?

Using the Ethereum protocol

How can you connect to an Ethereum node from the outside world?

Usually possible though: - HTTP (JSON-RPC) - IPC Sometimes: - Websockets

Every Ethereum node must implement a ............... interface.

JSON-RPC

What does dApp stand for?

Distributed application

What can dApps do? (2)

From simple p2p value transfer | To complicated token structures and more

Why to Smart Contracts make value transfer extremely easy? (2)

Because the economics and the logic are on the same layer. Additionally, you can save hardware and configuration by deploying the logic directly on the blockchain.

What is the nonce-field in a transaction?

To protect against replay attacks

The EVM is sandboxed, what is the implication of this?

It can’t access hardware layers or anything outside a blockchain node.

Name some advantages of dApps (4)

- Cutout the middle man - Run on a trusted platform - Apply logic to the blockchain where already economic assets are running - Allow peer to peer trade.

What does a Hashing Algorithm is deterministic mean?

Given the same input it always produces the same output

What Are Private Keys for?

To Sign Transactions and to derive a public key from which an address is determined

The............ Key signs transactions, the .......... key can verify the signature

Private | Public

.......... is computationally intensive which requires lots of energy. On the other hand, miners earn straightforward a reward for mining a block and incorporating transactions.

PoW

What are Externally Owned Accounts?

Are bound to a private key which is necessary to sign transactions outgoing from that account

Transactions containing the same data to create the ............ smart contract are having a different signature because of the ........... which changes upon every transaction

same | nonce

Sending one Ether is internally translated to ........

Wei, so it will send the equivalent of 10^18 Wei

Mining uses the ............... hashing while internally the EVM uses ............... which is similar to SHA256, but has different padding so it produces different hashes

Dagger-Hashimoto | Keccack256

Externally Owned Accounts keep their ..............., but on the blockchain a .......... is increased every time they send a transaction to avoid replay attacks

address | nonce

What is Ethereum?

A protocol defining how the communication should work. It is neither a proprietary software, nor patent. Instead it is open and there are several different implementations of the Ethereum protocol.

Name two implementations of the Ethereum protocol.

Go-ethereum a.k.a GETH (written in GO) | Parity (written in Rust)

In Ethereum everyone can start their own............ based on the Ethereum protocol. This means that the............ can be replicated in a way so that it works exactly the same way but doesn’t .........................

blockchain Main-Net Cost any real money

What are test networks usually used for?

To test distributed Applications (dApps) | To test new network functionalities, such as Proof of Stake.

What is the Ethereum network ID 0 called, and what is it used for?

Olympic, Ethereum public pre-release testnet

What is the Ethereum network ID 1 called, and what is it used for?

Frontier, Homestead, Metropolis, the Ethereum public main network

What is the Ethereum network ID 1 (chain ID 61) called, and what is it used for?

Classic, the (un)forked public Ethereum Classic main network.

What is the Ethereum network ID 1 (chain ID 2) called, and what is it used for?

Expanse, an alternative Ethereum implementation.

What is the Ethereum network ID 2 called, and what is it used for?

Morden, the public Ethereum testnet, now Ethereum Classic testnet