Intro to Proof of work

Assignment #1

What if I ask you the following question — Give me an input string that outputs a SHA-256 hash that starts with 00000 . How will you do it?

A: You will have to brute force until you find a value that starts with 00000

• Node.js code

  const crypto = require('crypto');
  
  // Function to find an input string that produces a hash starting with '00000'
  function findHashWithPrefix(prefix) {
      let input = 0;
      while (true) {
          let inputStr = input.toString();
          let hash = crypto.createHash('sha256').update(inputStr).digest('hex');
          if (hash.startsWith(prefix)) {
              return { input: inputStr, hash: hash };
          }
          input++;
      }
  }
  
  // Find and print the input string and hash
  const result = findHashWithPrefix('00000');
  console.log(`Input: ${result.input}`);
  console.log(`Hash: ${result.hash}`);

Assignment #2

What if I ask you that the input string should start with 100xdevs ? How would the code change?

• Node.js code

  const crypto = require('crypto');
  
  // Function to find an input string that produces a hash starting with '00000'
  function findHashWithPrefix(prefix) {
      let input = 0;
      while (true) {
          let inputStr = "100xdevs" + input.toString();
          let hash = crypto.createHash('sha256').update(inputStr).digest('hex');
          if (hash.startsWith(prefix)) {
              return { input: inputStr, hash: hash };
          }
          input++;
      }
  }
  
  // Find and print the input string and hash
  const result = findHashWithPrefix('00000');
  console.log(`Input: ${result.input}`);
  console.log(`Hash: ${result.hash}`);

Assignment #3

What if I ask you to find a nonce for the following input -

harkirat => Raman | Rs 100
Ram => Ankit | Rs 10

• Node.js code

  const crypto = require('crypto');
  
  // Function to find an input string that produces a hash starting with '00000'
  function findHashWithPrefix(prefix) {
      let input = 0;
      while (true) {
          let inputStr = `
  harkirat => Raman | Rs 100
  Ram => Ankit | Rs 10
  ` + input.toString();
          let hash = crypto.createHash('sha256').update(inputStr).digest('hex');
          if (hash.startsWith(prefix)) {
              return { input: inputStr, hash: hash };
          }
          input++;
      }
  }
  
  // Find and print the input string and hash
  const result = findHashWithPrefix('00000');
  console.log(`Input: ${result.input}`);
  console.log(`Hash: ${result.hash}`);

Assignment #4

Lets explore https://andersbrownworth.com/blockchain/