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How to Redact Secrets from Log Messages in Python
Build a lightweight RedactingFormatter class that replaces sensitive tokens like passwords and API keys with [REDACTED] before log messages are printed.
class RedactingFormatter:
def __init__(self, secrets):
self.secrets = secrets
def redact(self, message):
for secret in self.secrets:
message = message.replace(secret, "[REDACTED]")
return message
def format(self, record):
message = record["message"]
ret…Enforce TLS 1.2 Minimum in Python
Create an SSL context with a minimum TLS version of 1.2 to enforce secure connections.
import ssl
def get_min_tls_version():
context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
context.minimum_version = ssl.TLSVersion.TLSv1_2
return context.minimum_version
if __name__ == "__main__":
min_version = get_min_tls_version()
print(f"Minimum TLS version set to: {min_version.name} (value: {mi…Fetch Secrets from a Mock Secrets Manager in Python
Build a minimal in-memory secrets manager that stores and retrieves secret values, raising a KeyError for missing names.
import json
class SecretsManager:
"""Mock secrets manager that returns secrets from a local store."""
def __init__(self, store=None):
self.store = store or {
"api_key": "mock-api-key-123",
"db_password": "s3cret-p@ss",
"jwt_secret": "dev-only-secret"
}
…How to Check Negotiated Cipher Suite in Python
Connect to a TLS server with Python's ssl module and print the negotiated protocol version and cipher suite details.
import ssl
import socket
def get_cipher_suites(hostname, port=443):
context = ssl.create_default_context()
context.set_ciphers("DEFAULT:@SECLEVEL=2")
with socket.create_connection((hostname, port), timeout=5) as sock:
with context.wrap_socket(sock, server_hostname=hostname) as ssock:
…How to Create Secure Session Cookies in Python with Secure, HttpOnly, and SameSite Flags
This code demonstrates how to create a secure session cookie using Python's stdlib, setting Secure, HttpOnly, and SameSite attributes to protect against common web vulnerabilities.
import http.cookies
import secrets
class SessionManager:
def __init__(self):
self.cookie = http.cookies.SimpleCookie()
def create_session_cookie(self, session_id=None):
session_id = session_id or secrets.token_hex(16)
self.cookie["session"] = session_id
self.cookie["session"][…How to Enforce a Strict Referrer Policy in Python
Validate HTTP headers to enforce a strict same-origin Referrer policy, accepting only origin-only URLs or absent Referer values.
import re
from unittest.mock import patch
def strict_referrer_policy(headers):
"""Return True if Referer header is absent or strictly same-origin."""
referer = headers.get("Referer")
if referer is None:
return True
# Strict-Origin-When-Cross-Origin allows same-origin full URL
# but here we…How to Generate PKCE Code Challenge in Python
This Python script generates a PKCE code verifier and its corresponding S256 code challenge for secure OAuth2 authorization flows.
import base64
import hashlib
import os
import secrets
import string
def generate_code_verifier(length=64):
alphabet = string.ascii_letters + string.digits + "-._~"
return "".join(secrets.choice(alphabet) for _ in range(length))
def generate_code_challenge(code_verifier, method="S256"):
if method == "S256…How to Generate and Verify HMAC Signatures in Python
Create and validate HMAC-SHA256 signatures with a shared secret key using Python's hmac and hashlib modules.
import hashlib
import hmac
SECRET_KEY = b"pepper-secret-2024"
def generate_hmac(message: str) -> str:
return hmac.new(SECRET_KEY, message.encode("utf-8"), hashlib.sha256).hexdigest()
def verify_hmac(message: str, received_hmac: str) -> bool:
expected = generate_hmac(message)
return hmac.compare_digest(e…How to Hash Passwords Securely in Python
Hash passwords with PBKDF2, random salts, and constant pepper, plus generate secure API keys using Python's stdlib.
import hashlib
import secrets
import time
import hmac
def hash_password(password: str, salt: str = None, pepper: str = "static-pepper") -> dict:
"""Hash a password with a random salt and constant pepper."""
if salt is None:
salt = secrets.token_hex(16)
salted = f"{pepper}{salt}{password}"
dig…How to Hash Passwords with bcrypt in Python
Hash a plaintext password with bcrypt using a randomly generated salt, then verify a plaintext attempt against the stored hash.
import bcrypt
def hash_password(password: str) -> str:
"""Hash a password using bcrypt with a generated salt."""
salt = bcrypt.gensalt()
return bcrypt.hashpw(password.encode("utf-8"), salt).decode("utf-8")
def check_password(password: str, hashed: str) -> bool:
"""Verify a plaintext password against …How to Hash and Verify Passwords in Python
Hash passwords securely with PBKDF2-SHA256 and verify them using a constant-time comparison.
import hashlib
import hmac
import secrets
from typing import Tuple
def hash_password(password: str, salt: str = None) -> Tuple[str, str]:
"""Hash a password with a random salt using PBKDF2-SHA256."""
salt = salt or secrets.token_hex(16)
hashed = hashlib.pbkdf2_hmac(
"sha256", password.encode("utf…How to Implement an HSTS Preload List Mock in Python
Implements a mock HSTS preload list in Python that supports adding, removing, checking domains with subdomain inheritance, and listing domains.
import json
class HSTSPreloadList:
def __init__(self):
self.domains = {}
def add_domain(self, domain, include_subdomains=False, max_age=31536000):
self.domains[domain] = {
"include_subdomains": include_subdomains,
"max_age": max_age
}
def remove_domain(sel…How to Mock a Content Security Policy Header in Python
Mock a Content-Security-Policy header locally and verify it's served correctly using Python's built-in HTTP server.
import json
from http.server import BaseHTTPRequestHandler, HTTPServer
CSP_HEADER = "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'"
class MockServer(BaseHTTPRequestHandler):
def do_GET(self):
if self.path == "/":
self.send_response(200)
self.send_header("…How to Mock a Permissions Policy in Python
A lightweight Python class that simulates a browser Permissions-Policy header by tracking allowed/ denied feature permissions with get, set, reset, and bulk operations.
class PermissionsPolicy:
def __init__(self):
self._features = {
"geolocation": "self",
"camera": "self",
"microphone": "self",
"payment": "self",
"usb": "self",
}
def get_feature_policy(self, feature):
return self._features.ge…How to Revoke Tokens with a Blacklist Set in Python
A minimal TokenBlacklist class using a Python set to revoke, batch-revoke, check, and remove expired tokens for simple token invalidation.
import time
class TokenBlacklist:
def __init__(self):
self.blacklisted_tokens = set()
def revoke(self, token):
self.blacklisted_tokens.add(token)
print(f"Token {token} revoked. Blacklist size: {len(self.blacklisted_tokens)}")
def revoke_batch(self, tokens):
before = len(s…How to Salt Passwords per User in Python
Hash each user's password with a unique random salt using hashlib, and verify logins with timing-safe comparison.
import hashlib
import secrets
def hash_password(password: str, salt: str | None = None) -> tuple[str, str]:
"""Hash a password with a random salt (or provided salt).
Returns:
(salt_hex, password_hash_hex)
"""
if salt is None:
salt = secrets.token_hex(16)
salted = (salt + password)…How to Set X-Frame-Options DENY in Flask with a Mock Response
Set the X-Frame-Options header to DENY in a Flask response to prevent clickjacking, and verify it with Flask's test client.
from flask import Flask, Response
app = Flask(__name__)
@app.route("/")
def index():
response = Response("Hello, World!")
response.headers["X-Frame-Options"] = "DENY"
return response
if __name__ == "__main__":
with app.test_client() as client:
resp = client.get("/")
print(resp.get_da…How to Set a SameSite Cookie in Python
Set a SameSite cookie attribute in Python using the standard library's SimpleCookie class.
from http.cookies import SimpleCookie
def set_same_site_cookie(name, value, same_site="Lax"):
cookie = SimpleCookie()
cookie[name] = value
cookie[name]["path"] = "/"
cookie[name]["samesite"] = same_site
return cookie[name].OutputString()
if __name__ == "__main__":
print(set_same_site_cookie("…How to Verify Passwords in Constant Time in Python
Use hmac.compare_digest to verify passwords in constant time, preventing timing attacks that could reveal password length or character positions.
import hmac
import time
# Mock of a constant-time password comparison (prevents timing attacks)
def verify_password(stored_password: str, supplied_password: str) -> bool:
# hmac.compare_digest runs in constant time (for a given length)
return hmac.compare_digest(stored_password.encode(), supplied_password.enc…How to mock short TTL access tokens in Python
Simulate short-lived access tokens with a TTL, issue and validate them, and watch expiry behavior.
import time
import uuid
from datetime import datetime, timedelta
class AccessTokenManager:
def __init__(self, ttl_seconds=30):
self.ttl_seconds = ttl_seconds
self.tokens = {}
def issue_token(self):
token_id = uuid.uuid4().hex
expiry = datetime.now() + timedelta(seconds=self.t…How to Build a Mock Trivy Image Scan Gate in Python
Simulate a Trivy image scan and enforce a security gate that fails the pipeline when vulnerabilities meet or exceed a severity threshold.
import json
import sys
def mock_trivy_scan(image_name, severity_threshold="HIGH"):
"""Simulate a Trivy image scan result."""
mock_vulnerabilities = [
{"ID": "CVE-2023-1234", "Severity": "HIGH", "Package": "openssl", "FixedVersion": "3.0.9"},
{"ID": "CVE-2024-5678", "Severity": "CRITICAL", "Pa…How to Mock Docker Image Non-Root User in Python
This Python class simulates Docker image layers and inspects whether the final user is a non-root user, returning UID, GID, and security status.
from pathlib import Path
class DockerImageMock:
def __init__(self, name, tag):
self.name = name
self.tag = tag
self.layers = []
self.user = "root"
def add_file(self, path, content):
self.layers.append({"file": path, "content": content})
def set_user(self, usernam…Browse by section
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