ERC1155Soul

An ERC1155 soulbound token (SBT) impelementation with ultralow gas usage.

While minting 500 tokens, each SBT costs about ~7500 gas only. This is rouhly 4x ~ 5x lower than using the conventional ERC1155 implementations.

In addition, each SBT has its unique token ID. Namely, you will not see the SBTs overlapped with each other on the Opensea, and it is possible to give each SBT its unique metadata.

There are two varialnts, ERC1155Soul and ERC1155SoulContinuous. The token IDs of ERC1155SoulContinuous is always continuous. However, ERC1155Soul uses less gas. See benchmark for a more detailed comparision.

How it works

ERC1155Soul uses two facts to achieve the ultralow gas usage:

• Storing the data within the smart contract is much cheaper (uses less gas) than in the storage.
• A smart contract can create another smart contract.

When ERC1155Soul SBT is minted (airdroped), instead of storing the ownership information to the storage like most of the NFT implementation, it creates another smart contract. The ownership information is hardcoded inside the created smart contract. The smart contract is in general immutable, but its immutablility perfectly fits the application of SBT.

Installaion

npm

npm install erc1155soul

yarn

yarn add erc1155soul

Usage

pragma solidity >=0.8.0;

import "erc1155soul/contracts/ERC1155Soul.sol";

contract MySoulBoundToken is ERC1155Soul {

    /// @param tos are the array of the acconts to receive the SBTs.
    function mint(
        address[] calldata tos
    ) external {
        _mint(tos);
    }

    function uri(uint256 id) public view override returns (string memory) {
        return "https://my-soubound-metadata-uri/{id}";
    }

}

Benchmark

ERC1155Soul

# of token	total gas	gas per token
1	106519	106519
2	113603	56801
4	127765	31941
8	156095	19511
16	212750	13296
32	326059	10189
64	552685	8635
128	1005952	7859
256	1912554	7470
500	3641018	7282

ERC1155SoulContinuous

# of token	total gas	gas per token
1	128524	128524
2	135605	67802
4	149761	37440
8	178079	22259
16	234710	14669
32	347971	10874
64	574501	8976
128	1027576	8027
256	1933794	7553
500	3661526	7323