ERC-7201 Storage Namespaces Explained ERC-7201 (formerly EIP-7201) is a standard for grouping storage variables together by a common identifier called a namespace, and also to document the group of variables via NatSpec annotation. The purpose of the standard is to simplify managing storage variables during upgrades. Namespaces Namespaces are a common approach in programming languages […]
ERC-1363 Standard Explained ERC-1363 enables a smart contract to detect and respond to an incoming transfer of tokens. What problem does ERC-1363 Solve? Suppose a user transfers an ERC-20 token to a contract. The smart contract cannot credit the user for the transfer because it has no mechanism to see who made the transfer. Although […]
How ERC721 Enumerable Works An Enumerable ERC721 is an ERC721 with added functionality that enables a smart contract to list all the NFTs an address owns. This article describes how ERC721Enumerable functions and how we can integrate it into an existing ERC721 project. We’ll use Open Zeppelin’s popular implementation of ERC721Enumerable for our explanation. Prerequisites […]
ERC20 Votes: ERC5805 and ERC6372 ERC20 Votes Knowledge of ERC20 Snapshot is assumed, please refer to our article on ERC20 Snapshot for an introduction to the subject. ERC20 Votes does not actually handle conducting the poll, it’s still a regular ERC20 token with snapshot and delegated voting abilities. Voting is usually handled by governance contracts. […]
EIP 1967 Storage Slots for Proxies EIP 1967 is a standard for where to store information that proxy contracts need to execute. Both the UUPS (Universal Upgradeable Proxy Standard) and the Transparent Upgradeable Proxy Pattern use it. Remember: EIP 1967 only states where certain storage variables go and what logs get emitted when they change, […]
A comprehensive guide to the ERC 721 standard and related security issues ERC721 (or ERC-721) is the most widely used Ethereum standard for nonfungible tokens. It associates a unique number with an Ethereum address, thereby denoting that address owns the unique number — the NFT. There is indeed no shortage of tutorials covering this famous […]
Flash Loans and how to hack them: a walk through of ERC 3156 Flash loans are loans between smart contracts that must be repaid in the same transaction. This article describes the ERC 3156 flash loan specification as well as the ways flash lenders and borrowers can be hacked. Suggested security exercises are provided at […]
Solidity Staticcall EIP 214 Staticcall is like a regular Ethereum call except that it reverts if a state change happens. It cannot be used to transfer Ether. Both the EVM opcode, the Yul assembly function, and the built-in solidity function named staticcall. EIP 214 Staticcall was introduced in EIP 214 added to Ethereum in 2017 […]
EIP-2930 – Ethereum access list Introduction An Ethereum access list transaction enables saving gas on cross-contract calls by declaring in advance which contract and storage slots will be accessed. Up to 100 gas can be saved per accessed storage slot. The motivation for introducing this EIP was to mitigate breaking changes in EIP 2929, which […]