anCaptcha

No-JS, stateless captcha engine implemented in Rust for cross-language integration.

Security

Table of Contents

1. Overview
2. Key Features
3. Preview
4. Architecture
5. Configuration
6. Installation (Rust)
7. Quick Start
8. Custom Assets
9. Pre-built Library
10. Manual Verification
11. Security and Compliance
12. Repositories
13. License
14. Donation

Overview

AnCaptcha is a stateless captcha engine implemented in Rust for cross-language integration. Originally designed for Tor Browser's "Safest" mode where JavaScript is strictly disabled.

Key Features

• No-JavaScript: Challenges are entirely driven by CSS and HTML; no client-side scripts are required for rendering or interaction.
• Stateless Verification: Uses authenticated encryption (ChaCha20-Poly1305) to store challenge state in tokens, eliminating the need for server-side sessions.
• High-Level Wrappers: Ready-to-use implementations for Go, Python, and PHP are provided in the examples/ directory. Note: These are the only three officially supported language wrappers provided.

Preview

Style	Image
Rotate
Slider
Pair

Architecture

anCaptcha is structured as a workspace with the following core crates:

• crates/ancaptcha: Core engine handling challenge generation, authenticated encryption, and verification logic.
• crates/ancaptcha-ffi: C-ABI bridge for multi-language consumption.

Configuration

The engine is configured through a central Config struct (Rust) or via the FFI initialization calls (Wrappers).

Generate a 32-byte hex key for authenticated encryption:

openssl rand -hex 32

Global Configuration

Property	Type	Default	Description
secret	32-byte	(Required)	Key for authenticated encryption. must be identical across nodes.
difficulty	Enum	Medium	Challenge complexity: Easy (1 step), Medium (2 steps), Hard (3 steps).
noise_intensity	Enum	Medium	Distortion level (0: Low, 1: Medium, 2: High).

Captcha Styles

Style	Index	Description
Rotate	0	Rotate image to upright position.
Slider	1	Slide puzzle piece into place.
Pair	2	Find the matching image pair.

Visual Customization (Theme)

Default values for the Theme struct and anCaptcha_set_theme:

Property	Default	Description
background_color	#f9f9f9	Main container background.
border_color	#d3d3d3	Outer border color.
text_color	#333333	Primary text color.
accent_color	#14B8A6	Primary button/checkbox color.
error_color	#fb7185	Error message and invalid state color.
font_family	(System)	Sans-serif font stack.

Structural Customization (Layout)

Default values for the Layout struct and anCaptcha_set_layout:

Property	Default	Description
width	100%	Container width.
max_width	25em	Maximum container width.
margin	1.25em auto	Container margin.
min_height	3.5em	Initial trigger height.
padding	0.5em 0.9em	Container padding.
checkbox_size	1.8em	Custom checkbox dimensions.

Component Size Profile

Profile	Base Font Size	Description
Small	12px	Compact layout.
Medium	14px	Standard layout.
Large	16px	Large layout (Default).

Installation (Rust)

If you are not using Rust, skip directly to the Pre-built Library section below.

From Crates.io

cargo add ancaptcha

From My Registry

Add the registry to your local .cargo/config.toml:

[registries.maverick]
index = "sparse+https://git.mrmave.work/api/packages/maverick/cargo/"

[net]
git-fetch-with-cli = true

Then install:

cargo add ancaptcha --registry maverick

Quick Start (Build from Source)

Requires Linux and Rust.

# 1. Clone
git clone https://git.mrmave.work/maverick/ancaptcha.git

# Tor
git -c http.proxy=socks5h://127.0.0.1:9050 clone http://mavegitwskioz7tpppmjtj7fn24pwezciii3nvc7kdyltn5iu5uakfqd.onion/ancaptcha

# 2. Build
cd ancaptcha
make build

Custom Assets

You can add your own images by placing them in crates/ancaptcha/assets/original_images/. The pipeline converts .jpg, .jpeg, and .png files into optimized 200x200 WebP artifacts (<3.5KB).

make assets
make build

Pre-built Library (Go, Python, PHP)

Pre-built binaries, headers, and signatures are available in the dist/ directory or via Releases.

1. TL;DR Quick Setup (Wrappers)

Extract the FFI library and header, then download the wrapper for your language. Place all three files together in your project.

Go

wget -qO- https://git.mrmave.work/maverick/ancaptcha/releases/download/v0.4.1/ancaptcha-ffi-v0.4.1-linux-x86_64.tar.gz | tar -xz --strip-components=1 ancaptcha-ffi-v0.4.1-linux-x86_64/libancaptcha_ffi.so ancaptcha-ffi-v0.4.1-linux-x86_64/ancaptcha-ffi.h && wget -q https://git.mrmave.work/maverick/ancaptcha/raw/branch/main/examples/go/ancaptcha/ancaptcha.go

Go (Tor)

torsocks wget -qO- http://mavegitwskioz7tpppmjtj7fn24pwezciii3nvc7kdyltn5iu5uakfqd.onion/ancaptcha/plain/dist/ancaptcha-ffi-v0.4.1-linux-x86_64.tar.gz | torsocks tar -xz --strip-components=1 ancaptcha-ffi-v0.4.1-linux-x86_64/libancaptcha_ffi.so ancaptcha-ffi-v0.4.1-linux-x86_64/ancaptcha-ffi.h && torsocks wget -q http://mavegitwskioz7tpppmjtj7fn24pwezciii3nvc7kdyltn5iu5uakfqd.onion/ancaptcha/plain/examples/go/ancaptcha/ancaptcha.go

Python

wget -qO- https://git.mrmave.work/maverick/ancaptcha/releases/download/v0.4.1/ancaptcha-ffi-v0.4.1-linux-x86_64.tar.gz | tar -xz --strip-components=1 ancaptcha-ffi-v0.4.1-linux-x86_64/libancaptcha_ffi.so ancaptcha-ffi-v0.4.1-linux-x86_64/ancaptcha-ffi.h && wget -q https://git.mrmave.work/maverick/ancaptcha/raw/branch/main/examples/python/ancaptcha.py

Python (Tor)

torsocks wget -qO- http://mavegitwskioz7tpppmjtj7fn24pwezciii3nvc7kdyltn5iu5uakfqd.onion/ancaptcha/plain/dist/ancaptcha-ffi-v0.4.1-linux-x86_64.tar.gz | torsocks tar -xz --strip-components=1 ancaptcha-ffi-v0.4.1-linux-x86_64/libancaptcha_ffi.so ancaptcha-ffi-v0.4.1-linux-x86_64/ancaptcha-ffi.h && torsocks wget -q http://mavegitwskioz7tpppmjtj7fn24pwezciii3nvc7kdyltn5iu5uakfqd.onion/ancaptcha/plain/examples/python/ancaptcha.py

PHP

wget -qO- https://git.mrmave.work/maverick/ancaptcha/releases/download/v0.4.1/ancaptcha-ffi-v0.4.1-linux-x86_64.tar.gz | tar -xz --strip-components=1 ancaptcha-ffi-v0.4.1-linux-x86_64/libancaptcha_ffi.so ancaptcha-ffi-v0.4.1-linux-x86_64/ancaptcha-ffi.h && wget -q https://git.mrmave.work/maverick/ancaptcha/raw/branch/main/examples/php/AnCaptcha.php

PHP (Tor)

torsocks wget -qO- http://mavegitwskioz7tpppmjtj7fn24pwezciii3nvc7kdyltn5iu5uakfqd.onion/ancaptcha/plain/dist/ancaptcha-ffi-v0.4.1-linux-x86_64.tar.gz | torsocks tar -xz --strip-components=1 ancaptcha-ffi-v0.4.1-linux-x86_64/libancaptcha_ffi.so ancaptcha-ffi-v0.4.1-linux-x86_64/ancaptcha-ffi.h && torsocks wget -q http://mavegitwskioz7tpppmjtj7fn24pwezciii3nvc7kdyltn5iu5uakfqd.onion/ancaptcha/plain/examples/php/AnCaptcha.php

2. Manual Verification (Recommended)

Verify the release signatures before extraction to ensure cryptographic integrity.

# 1. Import Key
# Tor
torsocks wget http://mavegitwskioz7tpppmjtj7fn24pwezciii3nvc7kdyltn5iu5uakfqd.onion/ancaptcha/plain/certs/maverick.asc
gpg --import maverick.asc

# WKD
gpg --locate-keys mail@mrmave.work

# 2. Download Artifacts and Signatures
wget https://git.mrmave.work/maverick/ancaptcha/releases/download/v0.4.1/ancaptcha-ffi-v0.4.1-linux-x86_64.tar.gz
wget https://git.mrmave.work/maverick/ancaptcha/releases/download/v0.4.1/ancaptcha-ffi-v0.4.1-linux-x86_64.tar.gz.sha256
wget https://git.mrmave.work/maverick/ancaptcha/releases/download/v0.4.1/ancaptcha-ffi-v0.4.1-linux-x86_64.tar.gz.asc

# 3. Verify
sha256sum -c ancaptcha-ffi-v0.4.1-linux-x86_64.tar.gz.sha256
gpg --verify ancaptcha-ffi-v0.4.1-linux-x86_64.tar.gz.asc ancaptcha-ffi-v0.4.1-linux-x86_64.tar.gz

# 4. Extract
tar -xzf ancaptcha-ffi-v0.4.1-linux-x86_64.tar.gz

(Note: If accessing via Tor, use torsocks and replace the base URL with http://mavegitwskioz7tpppmjtj7fn24pwezciii3nvc7kdyltn5iu5uakfqd.onion/ancaptcha/plain/dist/ for all artifacts and signatures).

Security and Compliance

Continuous fuzzing and dependency auditing are integrated into the development process. Testing covers edge-case discovery in the verification engine and memory safety verification for the FFI bridge. The dependency manifest is also audited for security vulnerabilities and compliance. All security documentation, including fuzzing statistics, memory safety reports, and dependency audit logs, is available in docs/SECURITY.md.

Repositories

• Main: git.mrmave.work/maverick/ancaptcha
• Mirror (Tor): mavegit...onion/ancaptcha
• Mirror (Codeberg): codeberg.org/mrmave/ancaptcha

License

(c) 2026 Maverick. Licensed under the Apache-2.0 License.

Donation

Monero (XMR): 86FSeePspHNgbS29usjrtudPE1PTP2UjJLhB9vdXp3WjD9EYAibdS171SdT2dmcC7ZC6t9iPYd6StEeiXFNj6YNhRRcQyJi