Canto Identity Subprotocols contest - ginlee's results

[G1]Setting the constructor to payable cut out 10 opcodes in the creation-time EVM bytecode if you declare a constructor payable. Making the constructor payable eliminates the need for an initial check of msg.value == 0 and saves 13 gas on deployment with no security risks https://github.com/code-423n4/2023-03-canto-identity/blob/main/canto-bio-protocol/src/Bio.sol constructor() ERC721("Biography", "Bio") { if (block.chainid == 7700) { // Register CSR on Canto mainnnet Turnstile turnstile = Turnstile(0xEcf044C5B4b867CFda001101c617eCd347095B44); turnstile.register(tx.origin); } }

https://github.com/code-423n4/2023-03-canto-identity/blob/main/canto-namespace-protocol/src/Namespace.sol constructor( address _tray, address _note, address _revenueAddress ) ERC721("Namespace", "NS") Owned(msg.sender) { tray = Tray(_tray); note = ERC20(_note); revenueAddress = _revenueAddress; if (block.chainid == 7700) { // Register CSR on Canto mainnnet Turnstile turnstile = Turnstile(0xEcf044C5B4b867CFda001101c617eCd347095B44); turnstile.register(tx.origin); } }

https://github.com/code-423n4/2023-03-canto-identity/blob/main/canto-namespace-protocol/src/Tray.sol https://github.com/code-423n4/2023-03-canto-identity/blob/main/canto-pfp-protocol/src/ProfilePicture.sol

[G2]Use nested if and, avoid multiple check combinations https://github.com/code-423n4/2023-03-canto-identity/blob/main/canto-bio-protocol/src/Bio.sol if ((i > 0 && (i + 1) % 40 == 0) || prevByteWasContinuation || i == lengthInBytes - 1) if (nextCharacter & 0xC0 == 0x80) if ( // Note that we do not need to check i < lengthInBytes - 4, because we assume that it's a valid UTF8 string and these prefixes imply that another byte follows (nextCharacter == 0xE2 && bioTextBytes[i + 2] == 0x80 && bioTextBytes[i + 3] == 0x8D) || (nextCharacter == 0xF0 && bioTextBytes[i + 2] == 0x9F && bioTextBytes[i + 3] == 0x8F && uint8(bioTextBytes[i + 4]) >= 187 && uint8(bioTextBytes[i + 4]) <= 191) || (i >= 2 && bioTextBytes[i - 2] == 0xE2 && bioTextBytes[i - 1] == 0x80 && bioTextBytes[i] == 0x8D) )

[G3]Using storage instead of memory for structs/arrays saves gas https://github.com/code-423n4/2023-03-canto-identity/blob/077372297fc419ea7688ab62cc3fd4e8f4e24e66/canto-namespace-protocol/src/Namespace.sol#L133 Tray.TileData memory tileData = tray.getTile(trayID, tileOffset)

use storage instead of memory

[G4]Use constants instead of type(uintx).max https://github.com/code-423n4/2023-03-canto-identity/blob/077372297fc419ea7688ab62cc3fd4e8f4e24e66/canto-namespace-protocol/src/Tray.sol#L73 https://github.com/code-423n4/2023-03-canto-identity/blob/077372297fc419ea7688ab62cc3fd4e8f4e24e66/canto-namespace-protocol/src/Tray.sol#L122 https://github.com/code-423n4/2023-03-canto-identity/blob/077372297fc419ea7688ab62cc3fd4e8f4e24e66/canto-namespace-protocol/src/Tray.sol#L152

type(uintx).max uses more gas in the distribution process and also for each transaction than constant usage, uint256 constant MAX_VALUE = 2**256 -1, use this instead of type(uint256).max