#Here is an example of how you might implement a boot node in Kademlia using Python from scratch:

​

import hashlib

import random

import socket

​

# Generate a unique 160-bit node ID using SHA-1

def generate_node_id():

  h = hashlib.sha1()

  h.update(str(random.getrandbits(256)).encode())

  return h.hexdigest()

​

# Implement the routing table as a dictionary

# with keys being node IDs and values being

# tuples containing the node's IP address and port

routing_table = {}

​

# Create a socket for communication with other nodes

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

​

# Bind the socket to a specific IP address and port

sock.bind(('localhost', 8000))

​

# Generate a unique ID for this node

node_id = generate_node_id()

​

# Main loop to listen for incoming messages

while True:

  data, addr = sock.recvfrom(1024)

  message = data.decode()

  # Handle incoming PING message

  if message.startswith('PING'):

    sock.sendto('PONG'.encode(), addr)

  # Handle incoming FIND_NODE message

  elif message.startswith('FIND_NODE'):

    target_id = message.split(' ')[1]

    closest_nodes = []

    # Find the closest nodes in the routing table

    # using the XOR metric

    for node_id, node_addr in routing_table.items():

      distance = node_id ^ target_id

      closest_nodes.append((distance, node_addr))

    closest_nodes.sort()

    # Send the closest nodes back to the sender

    sock.sendto(str(closest_nodes).encode(), addr)

  # Handle incoming STORE message

  elif message.startswith('STORE'):

    key, value = message.split(' ')[1:]

    # Store the key-value pair in the routing table

    routing_table[key] = value

  # Handle incoming FIND_VALUE message

  elif message.startswith('FIND_VALUE'):

    key = message.split(' ')[1]

    # Look up the value in the routing table

    value = routing_table.get(key)

    if value is not None:

      # Send the value back to the sender

      sock.sendto(value.encode(), addr)

    else:

      # If the value is not found, send the closest

      # nodes in the routing table back to the sender

      closest_nodes = []

      for node_id, node_addr in routing_table.items():

        distance = node_id ^ key

        closest_nodes.append((distance, node_addr))

      closest_nodes.sort()

      sock.sendto(str(closest_nodes).encode(), addr)

​