Auth & security at scale
OAuth2, JWT, IAM patterns, secrets rotation, and least-privilege service auth.
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 Implement Refresh Token Rotation in Python
A mock auth service that issues, rotates, and validates refresh tokens, revoking old tokens on reuse to prevent replay attacks.
import time
import hashlib
import secrets
from typing import Dict, Optional, Tuple
class MockTokenService:
"""Simulates refresh token rotation for a simple auth system."""
def __init__(self):
# Token hash -> (user_id, rotation_count, expires_at)
self._active_tokens: Dict[str, Tuple[str, int,…How to Mock OAuth 2.0 Device Code Flow in Python
A mock implementation of the OAuth 2.0 device authorization grant for testing authentication flows without a real provider.
import hashlib
import time
import uuid
class DeviceCodeFlowMock:
def __init__(self):
self.device_codes = {}
def request_device_code(self, client_id, scope="read write"):
device_code = uuid.uuid4().hex
user_code = str(uuid.uuid4().int)[:8].upper()
expires_in = 300
inte…Mock client credentials machine auth in Python
This code simulates the OAuth2 client-credentials flow for service-to-service calls, generating a mock bearer token with expiry and caching, plus a revoke method, using only the standard library.
import time
import hashlib
import secrets
class MachineAuth:
"""Mock client-credentials machine auth for service-to-service calls."""
def __init__(self, client_id, client_secret):
self.client_id = client_id
self.client_secret = client_secret
self._token = None
self._expire…OAuth2 authorization code flow mock in Python
A minimal HTTP server that mocks the OAuth2 authorization code flow, issuing codes via /authorize and exchanging them for tokens at /token.
import json
from http.server import BaseHTTPRequestHandler, HTTPServer
from urllib.parse import urlparse, parse_qs
AUTH_CODE_STORE = {}
CLIENT_ID = "demo-client"
REDIRECT_URI = "http://localhost:8000/callback"
class OAuthHandler(BaseHTTPRequestHandler):
def do_GET(self):
parsed = urlparse(self.path)
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Auth & security at scale — Python code examples
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