Captcha Service implements a complete verification-code (captcha) flow: issue a code bound to a client cookie, verify it, and issue a short-lived token for further authorization. Includes rate limiting and expiry for security.

✨ Features

Feature	Description
🍪 Cookie Binding	Codes are bound to client cookies & IP
🔢 Code Generation	Generates verification codes with configurable expiry (default 120s)
🔑 Token Flow	Issues short-lived tokens (default 300s) after code verification
⏱️ Rate Limiting	Prevents spam (default 60s between requests)
🏥 Health Check	`/health` endpoint for monitoring

🔌 API Endpoints

POST `/apply`

Apply for a captcha (obtain a code).

Params: client cookie / info
Returns: captcha code & cookie binding

POST `/request_code`

Request a verification code.

Params: cookie / IP / target
Returns: code (subject to rate limit)

POST `/verify`

Verify a code.

Params: cookie, code
Returns: success / failure

POST `/check_token`

Validate an issued token.

Params: token
Returns: token validity + bound info

GET `/health`

Health check.

Returns: {status: ok}

🚀 Quick Start

Prerequisites

Python 3.7+
flask

Configure

Edit the config section in captcha_service.py:

VERIFY_CODE_EXPIRE_SECONDS = 120   # code expiry (s)
RATE_LIMIT_SECONDS = 60            # request interval limit (s)
TOKEN_EXPIRE_SECONDS = 300         # token expiry (s)

Run

python captcha_service.py

🗂️ Storage (in-memory)

Store	Purpose
`COOKIE_STORE`	Tracks cookies → cudid / ip / created_at
`CODE_STORE`	Holds issued codes with expiry & last-request
`TOKEN_STORE`	Holds issued tokens with expiry & usage status
`REQUEST_RECORD`	Rate-limiting record by cookie / IP

📄 License

Licensed under the MIT License. See LICENSE.

README.md

🔢 Captcha Service — Verification Code Generation & Verification