Blockchain interview homework

1/ Simple Signing & Verification api server using secp256k1

REQUIREMENTS

• The server provides 2 endpoints for Signing and Verifying:
• Use curve secp256k1
• Signing:
  • Input privateKey and message
  • Output string signature
  • Example:

    // Input 
    privateKey: b12dbc163d7935fba5ba11aba0691a11b2f6a2235c1ffa51718955e2e1da6249
    message: hello_world
    
    // Output: 
    3045022100e9116623942dbd89f1a37aa3e00ba5efda72ea28b7eb28a09f4739fcdad2c34e02204decb0dc4a5b59da7aa995b34d5e06cf3fe5dc85845719edf11e9e79d5792e59
    

• Verifying:
  • Input message, signature from the signing's output and publicKey
  • Output true | false indicate whether the signature is valid or not
  • Example:

    // Input
    message: hello_world
    signature: 3045022100e9116623942dbd89f1a37aa3e00ba5efda72ea28b7eb28a09f4739fcdad2c34e02204decb0dc4a5b59da7aa995b34d5e06cf3fe5dc85845719edf11e9e79d5792e59
    publicKey: 04b0c4047cd4e6f28593cff46cd99ad1ba9f65388dd7a641c50e34c0d5fbc4c0fdc6a827a966691c0e18dd0347464df79f623d9d86e2e566aeb25abf1da8c6f9a8
    
    // Output
    true
    

2/ Parse an ERC20 (Ethereum's token standard) transaction

REQUIREMENTS

• The application can be a CLI (read input from command line) or an API server
• Input: an ethereum transaction hash. Examples:
  • 0x3f9b5c3ba9f52a5876205a23359b3909b2ff61ec7b395688c32a5025efe9c306
  • 0x6cdb1d1d2828afe634323331e73c65b9d67b2fd1b71c95b3ff4597ec588c09b2
• Output: formated data from transaction's raw data. Examples

  // For transaction hash: 0x3f9b5c3ba9f52a5876205a23359b3909b2ff61ec7b395688c32a5025efe9c306
  // Output
  {
    transfers: [{
      from: '0xc2273e233bbaa8ea4651f43cbaa2ef464030aa66',
      to: '0x94f652d16928c760dc93a6c8b6d09b3859599730',
      amount: '1000000000000000000',
    }]
    hash: '0x3f9b5c3ba9f52a5876205a23359b3909b2ff61ec7b395688c32a5025efe9c306',
    blockHeight: 9460026
    contractAddress: '0x17a6cf4893f5c709c88f98c757d6361f1685a2f8',
  }
  

• You can not using any processed data from api service such as Etherscan.

MATERIALS

• To query a transaction's raw data, use infura.io. Register an account and get the api for mainnet. With an Infura API, you can interact with the ETH node through:
  • Web3
  • Manually send RPC requests to the API. You can read the ETH RPC spec here
• To check a transaction, use Etherscan

*For any questions, please submit an issue