Contest Rules

Overview

The PrivateBond Watermark Challenge is an open competition to build the most robust invisible watermarking system for images and video. Contestants submit Docker images that can embed and detect invisible watermarks. The community then tries to remove or destroy those watermarks. The systems that survive earn prizes from the USDT pool secured on Polygon.

Background: The Watermarking Problem

Digital watermarking is the art of creating detectable variations in media—subtle modifications that are invisible to the human eye but machine-recoverable. The core challenge is navigating a three-way tradeoff between embedding strength, visual quality, and wash survivability.

The Fundamental Tradeoffs

Approaches in the Field

Competitors may draw on any technique. The landscape includes:

Hybrid approaches are common and often perform best. There is no single “right” technique—the competition is designed to discover what works in practice against real adversaries.

The Video Problem

This competition accepts both images and video. Video watermarking introduces challenges that cannot be solved by frame-by-frame image watermarking. Temporal compression (H.264/H.265) discards inter-frame redundancy, I-frame/P-frame/B-frame encoding treats frames differently, and real-world video sharing involves aggressive re-encoding. Naturalistic perturbations in video (slight motion jitter, temporal color drift, micro-texture changes) create novel embedding opportunities that don't exist in still images, but also novel failure modes. Systems that handle both modalities will be evaluated on both.

Timeline

Submission Requirements

Your submission is a Docker image that exposes an HTTP server on port 8080 with the following endpoints:

{
  "image": "<base64 encoded image>",
  "payload": "<string, max 64 characters>"
}

{
  "watermarked_image": "<base64 encoded image>"
}

{
  "image": "<base64 encoded image>",
  "expected_payload": "<string, the payload to check for>"
}

{
  "detected": true,
  "confidence": 0.95,
  "payload": "<extracted payload string>"
}

{
  "video": "<base64 encoded video (MP4/WebM, max 30s, max 100MB)>",
  "payload": "<string, max 64 characters>"
}

{
  "watermarked_video": "<base64 encoded video>"
}

{
  "video": "<base64 encoded video>",
  "expected_payload": "<string, the payload to check for>"
}

{
  "detected": true,
  "confidence": 0.95,
  "payload": "<extracted payload string>"
}

{ "status": "ok" }

{ "status": "ok", "capabilities": ["image", "video"] }

Constraints

• •Container must be ready (health check passing) within 30 seconds of start.
• •Each image encode/decode request must complete within 10 seconds. Video: 60 seconds.
• •Maximum memory: 8 GB RAM.
• •No GPU access. CPU-only evaluation environment.
• •No outbound network access during evaluation.
• •Payload string is up to 64 characters (UTF-8).

Scoring

Knockoff Attacks

During the attack period, all watermarked output images are published. Anyone can download them and attempt to remove or destroy the watermark while keeping the image visually intact.

GitHub Repository Disclosure

At registration, each contestant submits a keccak256 hash of their GitHub repository URL. This hash is stored on-chain.

The actual repository URL is disclosed under any of these conditions:

• •The submission is knocked off (watermark removal verified).
• •The contestant wins a prize (top 3).
• •The contest ends (all repos disclosed after judging completes).

Prize Distribution

• A 5% platform fee is deducted from the total pool before distribution.
• Only non-knocked-off entries are eligible for prizes.
• Prizes are distributed in USDT on Polygon to the registered wallet address.
• If fewer than 3 eligible entries remain, the unclaimed portion rolls into future contests.

Disqualification

A submission may be disqualified for any of the following:

• •Docker image fails to start or pass health check within 30 seconds.
• •Encode or decode endpoints return errors on more than 10% of test images.
• •Container exceeds 8 GB memory limit or 10-second per-request timeout.
• •Malicious behavior detected (attempts to access host system, mine crypto, etc.).
• •Visible watermarks or significant visual degradation of images.
• •Use of a trivially broken or no-op watermarking scheme.
• •Multiple submissions from the same individual or team (one entry per person/team).