Shrusti-04

# captcha_app.py
# Simple CAPTCHA demo using `captcha` and Flask
# NOTE: For lab/demo only. Do not use this exact secret_key or plaintext keys in production.

from flask import Flask, render_template_string, request, session
from captcha.image import ImageCaptcha
import random, string, io, base64

app = Flask(__name__)
app.secret_key = "change_this_in_lab"  # replace with secure random key for real use

Shrusti-04

# password_cracker.py
import hashlib

def try_crack(hashfile="test_hashes.txt", wordlist="wordlist.txt"):
    targets = []
    with open(hashfile) as f:
        for line in f:
            salt_hex, h = line.strip().split(":")
            targets.append((bytes.fromhex(salt_hex), h))

Shrusti-04

# generate_hashes.py
import hashlib
import os

def hash_password(password, salt=None):
    if salt is None:
        salt = os.urandom(8)  # 8 bytes salt for demo
    h = hashlib.sha256(salt + password.encode()).hexdigest()
    return salt.hex(), h

Shrusti-04

# Experiment 2: Demo and Practice on Crypto Library

from cryptography.fernet import Fernet

# Step 1: Generate a key
key = Fernet.generate_key()
print("Encryption Key:", key)

# Step 2: Initialize Fernet object
cipher = Fernet(key)

Shrusti-04

# substitution_cipher.py
import string

# Caesar Cipher
def caesar_encrypt(plaintext, shift):
    plaintext = plaintext.upper()
    alphabet = string.ascii_uppercase
    ciphertext = ""
    for ch in plaintext:
        if ch in alphabet: