Dynamic CAPTCHA Challenge Updates via Risk Assessment

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Solution Overview

Problem

Existing CAPTCHA systems face challenges in distinguishing illegitimate human users, such as CAPTCHA farmers, from legitimate users, as they can solve multiple challenges and provide solutions to bots, making it difficult to prevent automated attacks on web resources.

Innovation Solution

A computer-implemented method dynamically updates a verification challenge based on user responses and risk assessment scores, replacing selected objects with new ones that meet or do not meet criteria, increasing the challenge's complexity and requiring multiple iterations to solve, thereby enhancing security against illegitimate users.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a static CAPTCHA challenge is used, then the system is simple to implement and operate, but illegitimate users can solve multiple challenges and provide solutions to bots, making it difficult to prevent automated attacks

Engineering Contradiction:
Improvesecurity against automated attacksVSAvoidcomplexity of verification challenge system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements dynamic CAPTCHA challenges that update in real-time based on user responses and risk assessment scores. The verification challenge transitions from a static state to a dynamic state where objects are replaced, criteria change, and difficulty adjusts automatically, making it difficult for automated systems to solve while maintaining manageable complexity through algorithmic control

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes parameters of the verification challenge including replacing objects, modifying selection criteria, and adjusting difficulty levels based on risk assessment scores. These parameter changes occur dynamically during the verification process, transforming the challenge into an adaptive security mechanism that responds to user behavior

Inventive Principle:
Principle #35Parameter changes

2Reliability

If a single-step verification challenge is used, then the user experience is simple and quick, but it cannot effectively distinguish illegitimate human users from legitimate users

Engineering Contradiction:
Improveability to distinguish legitimate usersVSAvoidmulti-step challenge structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The verification process is segmented into multiple steps where users must complete a series of challenges rather than a single challenge. Each step presents new objects and criteria, breaking down the verification into manageable segments that collectively provide robust discrimination between legitimate and illegitimate users

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The multi-step challenge structure is made dynamic through continuous updates between steps. Risk assessment scores are recalculated after each response, and subsequent challenges are generated with different objects and criteria, creating an adaptive multi-step process that maintains user experience while improving reliability

Inventive Principle:
Principle #15Dynamics

3Reliability

If verification challenges are updated frequently, then security against CAPTCHA farmers is improved, but the time required for users to complete verification increases

Engineering Contradiction:
Improvesecurity against CAPTCHA farmersVSAvoidverification completion time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system dynamically changes parameters including the number of update iterations and difficulty levels based on risk assessment scores. For low-risk users, fewer updates are required, reducing verification time, while high-risk users undergo more extensive verification, optimizing the balance between security and user experience through adaptive parameter adjustment

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3371732B1Dynamically updating captcha challenges
Publication Date: 2020.10.14 GOOGLE LLC
  • EP3371732B1 patent drawingFigure 1
  • EP3371732B1 patent drawingFigure 2~3
  • EP3371732B1 patent drawingFigure 4~5

AI summary

Systems and methods of dynamically updating CAPTCHA challenges are provided. For instance, a request to access an online resource can be received from a user device. A verification challenge can then be provided to the user device. One or more user responses to the verification challenge can be received. Each user response can correspond to an interaction by the user with an object from the plurality of objects. One or more risk assessment scores associated with the user can be determined based at least in part on the one or more user responses. The verification challenge can then be updated based at least in part on the one or more risk assessment scores and the one or more user responses.