Dapper / ERC-1271 wallet signature validation in Ruby

dapper.rb

require 'web3/eth'

ERC_1271_MAGIC_VALUE = '1626ba7e'
ERC_1271_ABI = <<~JSON
  [
    {
      "constant": true,
      "inputs": [
        {
          "name": "hash",
          "type": "bytes32"
        },
        {
          "name": "_signature",
          "type": "bytes"
        }
      ],
      "name": "isValidSignature",
      "outputs": [
        {
          "name": "magicValue",
          "type": "bytes4"
        }
      ],
      "payable": false,
      "stateMutability": "view",
      "type": "function"
    }
  ]
JSON

rpc_host = 'mainnet.infura.io'
rpc_path = '/v3/YOUR_RPC_PATH_HERE'

web3 = Web3::Eth::Rpc.new host: rpc_host,
  port: 443,
  connect_options: {
    use_ssl: true,
    rpc_path: rpc_path
  }

address = '0x77f7111B2b211BC504dE66b13F3A8a04cD182842'
challenge = Web3::Eth::Abi::Utils.keccak256('Follow Niftytown.com!')
signature = ['051912aa60d32687c0e9dc37d335b1bb226c24a31fca40a23cce11e8b417bee11ca668ead2e901ab276eea194e70c4eec71908f10fecc1390f187fb56d7ce2c81bd17faa5de3424c79cfc2dc8b0b074229efedc40cbeac8c835a373589b0b122277bae737503b29ceedf735ab2148523854be4818bb66c13a0b3f28349357678801c'].pack('H*')

contract = web3.eth.contract(ERC_1271_ABI)
wallet = contract.at(address)

result = wallet.isValidSignature(challenge, signature)

if result.unpack('H*').first == ERC_1271_MAGIC_VALUE
  puts 'Authorized'
else
  puts 'Unauthorized'
end