Secureum Bootcamp Ethereum 101 Quiz

Correct is C.

A stack machine is a computer processor or a virtual machine in which the primary interaction is moving short-lived temporary values to and from a push down stack.

from Stack machine - Wikipedia (opens in a new tab)

The EVM is a simple stack-based architecture consisting of the stack, volatile memory, non-volatile storage with a word size of 256-bit (chosen to facilitate the Keccak256 hash scheme and elliptic-curve computations) and Calldata.

from point 59 of Ethereum 101 - by Secureum (opens in a new tab)

Calldata is a read-only byte-addressable space where the data parameter of a transaction or call is held.

from point 63 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is B & C.

Block gas limit is set by miners and refers to the cap on the total amount of gas expended by all transactions in the block, which ensures that blocks can’t be arbitrarily large. Blocks therefore are not a fixed size in terms of the number of transactions because different transactions consume different amounts of gas.

from point 48 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is A & C.

EVM uses big-endian ordering where the most significant byte of a word is stored at the smallest memory address and the least significant byte at the largest

from point 65 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is D.

Given the aspirational absence of trusted intermediaries, everyone and everything is meant to be untrusted by default. Participants in this model include developers, miners/validators, infrastructure providers and users, all of whom could potentially be adversaries.

from point 95 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is C.

Turing-complete systems face the challenge of the halting problem i.e. given an arbitrary program and its input, it is not solvable to determine whether the program will eventually stop running. So Ethereum cannot predict if a smart contract will terminate, or how long it will run. Therefore, to constrain the resources used by a smart contract, Ethereum introduces a metering mechanism called gas.

from point 10 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is B.

Most EVM instructions operate with the stack (stack-based architecture) and there are also stack-specific operations e.g. PUSH, POP, SWAP, DUP etc.

from point 60 of Ethereum 101 - by Secureum (opens in a new tab)

Storage is a 256-bit to 256-bit key-value store. [...] This is accessed with SLOAD/SSTORE instructions.

from point 62 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is C.

SLOAD is 2100 gas and SSTORE is 20,000 gas to set a storage slot from 0 to non-0 and 5,000 gas otherwise. CREATE is 32000 gas and SELFDESTRUCT is 5000 gas.

from point 78 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is B.

Transaction properties: Atomic: it is all or nothing i.e. cannot be divided or interrupted by other transactions

from point 32 of Ethereum 101 - by Secureum (opens in a new tab)

A transaction reverts for different exceptional conditions such as running out of gas, invalid instructions etc. in which case all state changes made so far are discarded and the original state of the account is restored as it was before this transaction executed.

from point 79 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is A.

Gas price: The price a transaction originator is willing to pay in exchange for gas. The price is measured in wei per gas unit. The higher the gas price, the faster the transaction is likely to be confirmed on the blockchain. The suggested gas price depends on the demand for block space at the time of the transaction.

from point 35 of Ethereum 101 - by Secureum (opens in a new tab)

gasLimit: The maximum amount of gas the originator is willing to pay for this transaction value: The amount of ether (in wei) to send to the destination

from point 33 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is A, B, C.

On-chain vs Off-chain: Smart contracts are “on-chain” Web3 components and they interact with “off-chain” components that are very similar to Web2 software. So the major differences in security perspectives between Web3 and Web2 mostly narrow down to security considerations of smart contracts vis-a-vis Web2 software.

from point 90 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is C.

Ethereum account contains four fields: The nonce, a counter used to make sure each transaction can only be processed once...

from point 23 of Ethereum 101 - by Secureum (opens in a new tab)

A transaction is a serialized binary message that contains the following components: nonce: A sequence number, issued by the originating EOA, used to prevent message replay...

from point 33 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is B.

Gas price: The price a transaction originator is willing to pay in exchange for gas. The price is measured in wei per gas unit. The higher the gas price, the faster the transaction is likely to be confirmed on the blockchain. The suggested gas price depends on the demand for block space at the time of the transaction.

from point 35 of Ethereum 101 - by Secureum (opens in a new tab)

Block gas limit is set by miners and refers to the cap on the total amount of gas expended by all transactions in the block, which ensures that blocks can’t be arbitrarily large.

from point 48 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is B, D.

0x31 BALANCE 1 1 Get balance of the given account
0x40 BLOCKHASH 1 1 Get the hash of one of the 256 most recent complete blocks
0x44 DIFFICULTY 0 1 Get the block’s difficulty

(there's no operation to access transaction logs)

from points 70, 71 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is A, C.

Miners are rewarded for blocks accepted into the blockchain with a block reward in ether (currently 2 ETH). A miner also gets fees which is the ether spent on gas by all the transactions included in the block.

from point 47 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is A, C.

Web3: is a permissionless, trust-minimized and censorship-resistant network for transfer of value and information.

from point 88 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is C.

A hard fork to introduce an exponential difficulty increase, to motivate a transition to PoS when ready....

from "Ethereum’s Four Stages of Development" of Mastering Ethereum (opens in a new tab)

Correct is B, C.

0xf1 CALL 7 1 Message-call into an account
0xf2 CALLCODE 7 1 Message-call into this account with an alternative account’s code
0xf4 DELEGATECALL 6 1 Message-call into this account with an alternative account’s code, but persisting the current values for sender and value
0xfa STATICCALL 6 1 Static message-call into an account

from point 77 of Ethereum 101 - by Secureum (opens in a new tab)

Another variant of call is delegatecall, which replaced the more dangerous callcode. [...] Essentially, delegatecall runs the code of another contract inside the context of the execution of the current contract.

from "Calling Other Contracts (send, call, callcode, delegatecall)" of Mastering Ethereum (opens in a new tab)

Permits non-state-changing calls to itself or other contracts while disallowing any modifications to state during the call (and its subcalls, if present) to increase smart contract security and assure developers that re-entrancy bugs cannot arise from the call.

from "Appendix A: Ethereum Standards" of Mastering Ethereum (opens in a new tab)

Correct is B.

Ethereum state is made up of objects called "accounts", with each account having a 20-byte address and state transitions being direct transfers of value and information between accounts.

from point 22 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is B.

Gas refund and beneficiary: Any unused gas in a transaction (gasLimit minus gas used by the transaction) is refunded to the sender’s account at the same gasPrice. Ether used to purchase gas used for the transaction is credited to the beneficiary address (specified in the block header), the address of an account typically under the control of the miner. This is the transaction “fees” paid to the miner.

from point 56 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is C, D.

Solidity language continues to dominate smart contracts without much real competition (except Vyper perhaps).

from point 94 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is A.

Ethereum node/client: A node is a software application that implements the Ethereum specification and communicates over the peer-to-peer network with other Ethereum nodes.

from point 46 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is B.

EVM does not follow the standard von Neumann architecture. Rather than storing program code in generally accessible memory or storage, it is stored separately in a virtual ROM accessible only through a specialized instruction.

from point 64 of Ethereum 101 - by Secureum (opens in a new tab)

In computer science, a universal Turing machine (UTM) is a Turing machine that simulates an arbitrary Turing machine on arbitrary input. [...] This principle is considered to be the origin of the idea of a stored-program computer used by John von Neumann in 1946 for the "Electronic Computing Instrument" that now bears von Neumann's name: the von Neumann architecture.[1]

from Universal Turing machine - Wikipedia (opens in a new tab)

Correct is D.

Inclusion: Transaction inclusion is not guaranteed and depends on network congestion and gasPrice among other things. Miners determine inclusion. Order: Transaction order is not guaranteed and depends on network congestion and gasPrice among other things. Miners determine order.

from point 32 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is C.

Ethereum has two different types of accounts: Externally Owned Accounts (EOAs) controlled by private keys Contract Accounts controlled by their contract code

from point 24 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is C.

Ethereum’s currency unit is called ether or “ETH.” Ether is subdivided into smaller units and the smallest unit is named wei. [...] and 10**18 wei is 1 Ether.

from point 17 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is A, B, C.

See the Ethereum Whitepaper (opens in a new tab)

Consensus algorithm: Ethereum uses Bitcoin’s consensus model, Nakamoto Consensus

from point 9 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is C.

Audit-as-a-Silver-Bullet: Secure Software Development Lifecycle (SSDLC) processes for Web2 products have evolved over several decades to a point where they are expected to meet some minimum requirements of a combination of internal validation, external assessments (e.g. product/process audits, penetration testing) and certifications depending on the value of managed assets, anticipated risk, threat model and the market domain of products (e.g. financial sector has stricter regulatory compliance requirements).

from point 100 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is C.

Blocks contain block header, transactions and ommers’ block headers. Block header contains [...] stateRoot, transactionsRoot and receiptsRoot are 256-bit hashes of the root nodes of modified Merkle-Patricia trees.

from points 53, 54 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is B, D.

The code in Ethereum contracts is written in a low-level, stack-based bytecode language, referred to as "Ethereum virtual machine code" or "EVM code". The code consists of a series of bytes (hence called bytecode), where each byte represents an operation.

from points 58 of Ethereum 101 - by Secureum (opens in a new tab)

Most EVM instructions operate with the stack (stack-based architecture) and there are also stack-specific operations e.g. PUSH, POP, SWAP, DUP etc.

from points 60 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is B.

Gas costs for different instructions are different depending on their computational/storage load on the client

from points 78 of Ethereum 101 - by Secureum (opens in a new tab)

Tangerine Whistle — A hard fork to change the gas calculation for certain I/O-heavy operations and to clear the accumulated state from a denial-of-service (DoS) attack that exploited the low gas cost of those operations. Spurious Dragon — A hard fork to address more DoS attack vectors, and another state clearing. Also, a replay attack protection mechanism.

from "Ethereum’s Four Stages of Development" of Mastering Ethereum (opens in a new tab)

Correct is B.

The EVM is a simple stack-based architecture consisting of the stack, volatile memory, non-volatile storage with a word size of 256-bit (chosen to facilitate the Keccak256 hash scheme and elliptic-curve computations) and Calldata.

from points 59 of Ethereum 101 - by Secureum (opens in a new tab)

Correct is B, C, D.

0x31 BALANCE 1 1 Get balance of the given account
0x3f EXTCODEHASH 1 1 Get hash of an account’s code
0x40 BLOCKHASH 1 1 Get the hash of one of the 256 most recent complete blocks
0x43 NUMBER 0 1 Get the block’s number

from points 70, 71 of Ethereum 101 - by Secureum (opens in a new tab)