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Contract Cops
  • Mastering Ethereum Book
    • What is ethereum?
    • Tokens
    • Oracles
    • Decenralized Applications(DApps)
    • The Ethereum virtual machine
    • Ethereum basics
    • Ethereum clients
    • Cryptography
    • Wallets
    • Transactions
    • Chapter 7 - Smart Contracts & Solidity
    • Side Notes
      • Tokens
      • Smart Contracts and Solidity
  • Cryptography
    • Ethereum Cryptography - Cheatsheet
    • Assymetric vs symmetric cryptography
    • ECDSA vs RSA
    • Elliptic curves and ECDSA
    • Sha-256 Example
    • Sha-256
    • What are the different steps in SHA-256?
  • Ethereum Blocks
    • Block Headers
  • Learning Solidity
    • Storage vs memory
    • Upgradeable contracts
      • Proxy pattern in smart contracts
  • PoS
    • Proof of stake
  • PoW
    • PoW
  • Tokens
    • ERC-1155
    • ERC20
  • Cryptonomics
    • Automated market makers
    • Collateral Tokens
    • Collateralized Stablecoin
    • Fiat currency
    • Liquidity pool
    • Open Position: Meaning and Risk in Trading
    • Slippage
    • Spot price
  • Common Attack Vectors
    • Checking access control
    • Access control issues on critical functions
    • Account Existence Check for low level calls
    • Account Existence Check
    • Common attacks with contract/EOA addresses
    • Arithmetic under/overflow
    • Assert Attack
    • Assert require revert
    • Assert Violation
    • Bad Interface DOS
    • Bad pragma and compiler
    • Block Timestamp Manipulation
    • Bypassing contract check
    • Code With No Effects
    • Code size check vulnerability
    • Constructors with Care
    • Default Visibilities
    • Delegatecall
    • Delegatecall
    • Denial of Service (DoS)
    • DoS with block gas limit
    • Entropy Illusion
    • External contract referencing
    • Flash Loan Attack
    • Floating Point and Precision
    • Function selector abuse
    • Function selector abuse
    • Smart contract gas griefing
    • Hash collision parameters
    • Hash Collisions With Multiple Variable Length Arguments
    • Imprecise arithmetic
    • Improper Array Deletion
    • Incorrect array deletion
    • Incorrect interface
    • Insufficient Gas Griefing
    • Loop through long arrays
    • Message call with hardcoded gas amount
    • Not enough gas for ether transfer
    • Precision Loss in Calculations
    • Oracle Manipulation
    • Public Burn Function
    • Read-only reentrancy
    • Race Conditions/Front Running
    • Reentrancy Attacks
    • Reentrancy
    • Requirement Violation
    • Right-To-Left-Override control character (U+202E)
    • Shadowing State Variables
    • Short Address / Parameter attack
    • Signature Malleability
    • Signature Replay
    • Transaction Order Dependence
    • Tx.Origin Authentication
    • Unchecked CALL Return Values
    • Unexpected ether
    • Uninitialized Storage Pointers
    • Unsafe Ownership Transfer
  • EIP's
    • EIP155
    • EIP55
  • PoW
    • Ethash
    • Scrypt - RFC 7914
  • Questions for self evaluation
    • Questions 23/04/2023 (Nr: 84)
    • Usability guide for questions
  • Frequently asked questions
    • What is the difference between transaction and message?
    • What is the use of a interface or function without implementation?
  • UsefulResources
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  1. Questions for self evaluation

Questions 23/04/2023 (Nr: 84)

  • What are the different types of tokens, and can you provide an example for each type?

  • What is the difference between fungible and non-fungible tokens?

  • What is the difference between intrinsic and extrinsic tokens?

  • What is the difference between utility and equity tokens?

  • What is ERC223 and ERC721?

  • What is the ERC20 standard, and what are the required and optional functions defined by it?

  • What is the main purpose of oracles in the Ethereum blockchain?

  • What is the Immediate Read Oracle design pattern, and can you provide an example of its use?

  • What is the Request-Response Oracle design pattern, and how does it work?

  • What are the two main ways of data authentication for oracles?

  • What is IPFS, and how does it work?

  • What is Swarm, and how is it similar to IPFS?

  • What are Decentralized Message Communications Protocols, and which one is the most notable for DApps?

  • What is ENS?

  • What is the issue of governance in DApps?

  • Why is the nonce value in a transaction important?

  • How are nonces tracked, and what are the issues that can arise with nonces?

  • What is the Ethereum Virtual Machine (EVM)?

  • What is the Ethereum world state?

  • What is the difference between the code used when creating and deploying a smart contract?

  • What is gas in the context of the EVM, and how does it work?

  • What are smart contracts, and what is their functionality?

  • What are the characteristics of smart contracts?

  • What is the lifecycle of a smart contract, and how is it triggered?

  • What is the difference between declarative and imperative programming languages, and can you provide some examples of each?

  • What is the Solidity ABI, and how is it used?

  • What is Ethereum, and what are its key components?

  • How does Ethereum deal with DoS attacks and overuse of resources?

  • What is gas in Ethereum, and how is it used?

  • What is the incentive for participants in Ethereum's consensus algorithm?

  • What is the structure of a transaction?

  • How does the ECDSA work?

  • Explain the PoS algorithm.

  • Explain the PoW algorithm.

  • What is the difference between HD wallets and deterministic (seeded) wallets and nondeterministic (random) wallets?

  • What is the difference between a transaction and a message?

  • What is the use of an interface or function without implementation?

  • What are automated market makers?

  • What are collateral tokens?

  • What is a collateralized stablecoin?

  • What is fiat currency?

  • What is a liquidity pool?

  • Explain open position, its meaning, and risk in trading.

  • What is slippage?

  • What is spot price?

  • Explain asymmetric vs symmetric cryptography.

  • Explain what SHA-256 is, how it works, and its usage.

  • Explain what you know about storage vs. memory vs. calldata.

  • How can access control vulnerability arise?

  • Explain the account existence check for low-level calls.

  • Explain the arithmetic under/overflow vulnerability.

  • Explain the assert attack.

  • Explain the bad interface DOS vulnerability.

  • Explain the block timestamp manipulation vulnerability.

  • What is the bypassing contract check vulnerability?

  • Can you produce code with no effects in Solidity?

  • Explain the code size check vulnerability.

  • Explain the low-level function Delegatecall and the vulnerability that can occur when using it without caution.

  • Explain Denial of Service (DoS) attacks in Solidity.

  • Explain DoS with block gas limit.

  • Explain the concept of entropy illusion.

  • Explain the flash loan attack.

  • Explain the floating point and precision vulnerabilities.

  • Explain the function selector abuse vulnerability.

  • Explain smart contract gas griefing.

  • Explain hash collision and what parameters can lead to it.

  • What is improper array deletion in Solidity?

  • Explain call/transfer with hardcoded gas amount and how it can lead to a vulnerability

  • Explain the oracle manipulation vulnerability

  • Explain the public burn function vulnerability

  • Explain the read-only reentrancy vulnerability

  • Explain the single function reentrancy vulnerability

  • Explain the cross function reentrancy vulnerability

  • What is Race Conditions/Front Running vulnerability

  • Very briefly explain Right-To-Left-Override control character (U+202E) vulnerability

  • What does it mean to shadow state Variables?

  • Very briefly explain Short Address / Parameter attack

  • Explain Signature Malleability

  • Explain Signature Replay

  • What issues can arise from using Tx.origin ?

  • Explain Unchecked CALL Return Values vulnerability

  • Explain Unexpected ether vulnerability?

  • Explain Uninitialized Storage Pointers vulnerability?

  • How can we prevent unsafe iwnership transfer?

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Last updated 2 years ago