Keyed Human Interactive Proof Player for Relay Attack Defense
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Solution Overview
Problem
Traditional human interactive proof (HIP) systems are vulnerable to relay attacks, where a human is exploited to solve CAPTCHA puzzles, making it economically inefficient to defend against unauthorized access, as the cost of defeating the system is relatively low for adversaries.
Innovation Solution
A keyed HIP system that uses a browser plug-in to animate and solve puzzles, making the process costly for adversaries by requiring substantial computational resources on the client and minimizing server costs, while ensuring that each account opening and spam-like message sends incur higher costs due to unique, obfuscated, and time-dependent puzzle solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional HIP systems use simple image-based CAPTCHA with transformed characters, then the system is easy to implement and deploy, but it is vulnerable to relay attacks and can be broken using simple OCR techniques
Solution Approach 1:
The HIP system is divided into multiple independent components: a server that generates puzzle descriptions and validation logic, and a client-side player that renders and animates the puzzle. This segmentation allows the server to remain simple while the client handles the complex rendering, making the system both easy to implement and secure against relay attacks.
Solution Approach 2:
The patent introduces animation and time-dependent rendering of HIP puzzles through the client-side player. The puzzle is not a static image but a dynamic animation that changes over time, making it vulnerable to relay attacks while maintaining ease of implementation through modular architecture.
2Use of energy by stationary object
If HIP puzzles are rendered as static images with transformed characters, then the server computational resources are minimal, but the system can be easily broken by OCR techniques and relay attacks
Solution Approach 1:
The complex rendering and animation logic is extracted from the server and placed in the client-side player. The server only needs to generate simple puzzle descriptions and validate solutions, minimizing its computational resources, while the client handles the secure dynamic rendering that resists OCR and relay attacks.
Solution Approach 2:
The client-side player acts as an intermediary between the server's simple puzzle description and the user's interaction. It renders the animated puzzle locally, preventing the server from needing complex rendering capabilities while maintaining security against automated attacks.
3Ease of operation
If relay attacks are allowed where humans solve HIP puzzles for pay or free services, then the HIP system can be defeated at low cost, but this defeats the purpose of the HIP
Solution Approach 1:
The system performs preliminary binding of the puzzle rendering to the client's environment during the animation playback. The puzzle's visual characteristics and timing are determined dynamically during rendering, before the user provides the solution. This preliminary action ensures that the puzzle cannot be easily relayed or solved by external humans, as the specific animated sequence is unique to that client instance.
4Reliability
If the HIP player requires substantial computational resources on the client side, then relay attacks become costly, but this increases the burden on legitimate users
Solution Approach 1:
The patent changes the parameters of the HIP system by using animated, time-dependent puzzles rendered client-side rather than static images. This parameter change increases the cost to adversaries attempting relay attacks while maintaining ease of operation for legitimate users through the automated player.
Data Source
AI summary
A human interactive puzzle (HIP) authorization architecture where keyed and animated puzzles are executed by HIP players which are distinct and obfuscated to the point where breaking a single player is a relatively costly operation. A key is created in response to a request for a service, a HIP player is created based on the key, and a small installation executable is created that expands during installation to produce a computationally expensive data structure on the client relative to verification of the solution at the server. Thus, copying of the player or relay of the puzzle to a third system requires more time than allowed to receive the solution at the server.