Base58 Encoder

const BASE58_CHARS = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz';

function base58Encode(bytes) {
  // Handle leading zeros
  let zeros = 0;
  for (const b of bytes) {
    if (b === 0) zeros++;
    else break;
  }

  // Convert bytes to big integer
  let num = BigInt(0);
  for (const byte of bytes) {
    num = num * 256n + BigInt(byte);
  }

  // Convert to base58
  let result = '';
  while (num > 0n) {
    result = BASE58_CHARS[Number(num % 58n)] + result;
    num = num / 58n;
  }

  // Add leading '1's for leading zeros
  return '1'.repeat(zeros) + result;
}

// Example: encode "Hello"
const bytes = new TextEncoder().encode('Hello');
base58Encode(bytes);  // "9Ajdvzr"