Create IPFS CID v0 and v1 in Solidity

This repo includes:

• the first complete implementation of Base32 encode/decode in Solidity
• code to calculate IFPS CID v0 and v1 based on SHA256 hash of the content (e.g. metadata json file)

Github: https://github.com/0x00000002/ifps-cid-solidity

CIDv0

CIDv0 looks like QmX9qyMvfYRfho16oYNDZbwHyrGRJPgZWxHX2PcqMkbs9M.

Base58 encoding was implemented by @storyicon, and used here as a library when creating CIDv0.

Implementation:

    function cidv0(bytes32 sha256Hash) public pure returns (string memory) {
        bytes memory hashString = new bytes(34);
        hashString[0] = 0x12;
        hashString[1] = 0x20;
        uint256 hashLength = sha256Hash_.length;
        for (uint256 i = 0; i < hashLength; ++i) {
            hashString[i + 2] = sha256Hash[i];
        }
        return Base58.encodeToString(hashString);
    }

CIDv1

CIDv1 looks like bafkreidon73zkcrwdb5iafqtijxildoonbwnpv7dyd6ef3qdgads2jc4sy and uses Base32 encoding.

The AI-drafted Base32 encoder implementation was used to create CIDv1.

Implementation

    function cidv1(bytes32 sha256Hash) public pure returns (string memory) {
        bytes memory hashString = new bytes(36);
        hashString[0] = 0x01;
        hashString[1] = 0x70;
        hashString[2] = 0x12;
        hashString[3] = 0x20;
        uint256 hashLength = sha256Hash.length;
        for (uint256 i = 0; i < hashLength; ++i) {
            hashString[i + 4] = sha256Hash[i];
        }
        return Base32.encodeToString(hashString);
    }

Usage

Prerequisites

Base32.sol can be imported and used as a library. Using this CIDv0/v1 will require installing some dependencies.

1. Foundry should be installed. https://book.getfoundry.sh/getting-started/installation

2. Install dependencies

   forge install OpenZeppelin/openzeppelin-contracts
   forge install storyicon/base58-solidity
   forge install foundry-rs/forge-std

Usage example

contract NFT {
   ...
   mapping(uint256 tokenId => string) private _tokenURIs;
   ...
   function setURI_CIDv0(uint256 tokenId, bytes32 sha256Hash) external {
      _tokenURIs[tokenId] =
         string(abi.encodePacked(IPFS_URI, cidv0(sha256Hash)));
   }
   ...
   function setURI_CIDv1(uint256 tokenId, bytes32 sha256Hash) external {
      _tokenURIs[tokenId] =
         string(abi.encodePacked(IPFS_URI, cidv1(sha256Hash)));
   }

}

See also tests in NFT.t.sol