Dynamic Image CAPTCHA for Mobile Terminals
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Solution Overview
Problem
Existing CAPTCHAs face difficulties in being executed by mobile terminals due to varying display screen sizes, resolutions, and input methods, making it challenging to provide an effective authentication mechanism.
Innovation Solution
A CAPTCHA provision method that determines the type of web browser on the user terminal and selects an appropriate CAPTCHA execution program, specifically using an image CAPTCHA program for mobile terminals, where users move images on the screen to authenticate, with the server determining success based on the relative position of images within a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional text-based CAPTCHA is used, then security authentication is achieved, but execution becomes difficult on mobile terminals with different screen sizes and input methods
Solution Approach 1:
The patent changes the interaction parameters from text input to image manipulation. Users drag images to specified positions instead of typing text, adapting the CAPTCHA interaction mode to mobile terminal characteristics while maintaining authentication security through position verification
Solution Approach 2:
The patent introduces dynamic image positioning where the correct position of images changes with each CAPTCHA instance. The system dynamically generates different position coordinates and validates user drag operations against these dynamic targets, ensuring both security and adaptability to mobile devices
2Ease of operation
If CAPTCHA is adapted for mobile terminals with simplified interaction, then ease of execution improves, but authentication security may be compromised
Solution Approach 1:
The system provides immediate feedback by displaying the dragged image at the user-selected position and comparing it with the correct position coordinates stored in the database. This feedback mechanism allows real-time verification while maintaining simple drag-and-drop interaction suitable for mobile terminals
Solution Approach 2:
The system pre-stores correct position coordinates in the database before the user interaction begins. This preliminary preparation enables rapid validation of user drag operations without complex real-time calculations, maintaining both security and ease of use on mobile devices
3Adaptability or versatility
If multiple CAPTCHA execution programs are maintained for different terminals, then adaptability improves, but system complexity increases
Solution Approach 1:
The patent creates a universal image-based CAPTCHA execution program that functions across both mobile and personal computer terminals. The core drag-and-drop image interaction mode works on touch screens and mouse interfaces alike, eliminating the need for separate CAPTCHA systems while maintaining terminal compatibility
Solution Approach 2:
The system separates the CAPTCHA execution logic into independent modular components: image display, user interaction handling, position validation, and result processing. This segmentation allows the same program to adapt to different terminal types without increasing overall system complexity
Data Source
Figure 1(A)~1(B)
Figure 2(A)~2(B)
Figure 3(A)~3(C)
AI summary
[Problem] To selectively provide, in accordance with a user terminal a CAPTCHA that can be easily executed by an operator of the user terminal. [Solution] A web server (11) determines the type of web browser running in a user terminal (13). An authentication server (12) decides a CAPTCHA execution program on the basis of the type of web browser that has been determined. The authentication server (12) executes the decided CAPTCHA execution program to generate problem data and correct answer data. The web server (11) provides the CAPTCHA to the user terminal (13) on the basis of the problem data. The authentication server (12) compares the correct answer data and answer data generated by the user terminal (13), and determines whether authentication has succeeded or failed.