CAPTCHA: Machine or human solvers? a game-theoretical analysis

Zhen Li; Qi Liao

doi:10.1109/CSCloud/EdgeCom.2018.00013

CAPTCHA: Machine or human solvers? a game-theoretical analysis

Zhen Li, Qi Liao

Computer Science

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

4 Scopus citations

Abstract

CAPTCHAs have become an ubiquitous defense used to protect open web resources from being exploited at scale. Traditionally, attackers have developed automatic programs known as CAPTCHA solvers to bypass the mechanism. With the presence of cheap labor in developing countries, hackers now have options to use human solvers. In this research, we develop a game theoretical framework to model the interactions between the defender and the attacker regarding the design and countermeasure of CAPTCHA system. With the result of equilibrium analysis, both parties can determine the optimal allocation of software-based or human-based CAPTCHA solvers. Counterintuitively, instead of the traditional wisdom of making CAPTCHA harder and harder, it may be of best interest of the defender to make CAPTCHA easier. We further suggest a welfare-improving CAPTCHA business model by involving decentralized cryptocurrency computation.

Original language	English
Title of host publication	Proceedings - 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018
Editors	Meikang Qiu
Publisher	Institute of Electrical and Electronics Engineers Inc.
Pages	18-23
Number of pages	6
ISBN (Print)	9781538658505
DOIs	https://doi.org/10.1109/CSCloud/EdgeCom.2018.00013
State	Published - Jul 27 2018
Event	5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018 - Shanghai, China Duration: Jun 22 2018 → Jun 24 2018

Publication series

Name	Proceedings - 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018

Conference

Conference	5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018
Country/Territory	China
City	Shanghai
Period	06/22/18 → 06/24/18

Keywords

Bitcoins
Blockchain
CAPTCHA
Computer Security
Cryptocurrency
Economics
Game Theory
Human Solver
Machine Solver

Access to Document

10.1109/CSCloud/EdgeCom.2018.00013

Cite this

Li, Z., & Liao, Q. (2018). CAPTCHA: Machine or human solvers? a game-theoretical analysis. In M. Qiu (Ed.), Proceedings - 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018 (pp. 18-23). Article 8421846 (Proceedings - 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018). Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/CSCloud/EdgeCom.2018.00013

Li, Zhen ; Liao, Qi. / CAPTCHA : Machine or human solvers? a game-theoretical analysis. Proceedings - 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018. editor / Meikang Qiu. Institute of Electrical and Electronics Engineers Inc., 2018. pp. 18-23 (Proceedings - 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018).

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title = "CAPTCHA: Machine or human solvers? a game-theoretical analysis",

abstract = "CAPTCHAs have become an ubiquitous defense used to protect open web resources from being exploited at scale. Traditionally, attackers have developed automatic programs known as CAPTCHA solvers to bypass the mechanism. With the presence of cheap labor in developing countries, hackers now have options to use human solvers. In this research, we develop a game theoretical framework to model the interactions between the defender and the attacker regarding the design and countermeasure of CAPTCHA system. With the result of equilibrium analysis, both parties can determine the optimal allocation of software-based or human-based CAPTCHA solvers. Counterintuitively, instead of the traditional wisdom of making CAPTCHA harder and harder, it may be of best interest of the defender to make CAPTCHA easier. We further suggest a welfare-improving CAPTCHA business model by involving decentralized cryptocurrency computation.",

keywords = "Bitcoins, Blockchain, CAPTCHA, Computer Security, Cryptocurrency, Economics, Game Theory, Human Solver, Machine Solver",

author = "Zhen Li and Qi Liao",

note = "Publisher Copyright: {\textcopyright} 2018 IEEE.; 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018 ; Conference date: 22-06-2018 Through 24-06-2018",

year = "2018",

month = jul,

day = "27",

doi = "10.1109/CSCloud/EdgeCom.2018.00013",

language = "English",

isbn = "9781538658505",

series = "Proceedings - 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018",

publisher = "Institute of Electrical and Electronics Engineers Inc.",

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editor = "Meikang Qiu",

booktitle = "Proceedings - 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018",

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Li, Z & Liao, Q 2018, CAPTCHA: Machine or human solvers? a game-theoretical analysis. in M Qiu (ed.), Proceedings - 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018., 8421846, Proceedings - 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018, Institute of Electrical and Electronics Engineers Inc., pp. 18-23, 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018, Shanghai, China, 06/22/18. https://doi.org/10.1109/CSCloud/EdgeCom.2018.00013

CAPTCHA: Machine or human solvers? a game-theoretical analysis. / Li, Zhen; Liao, Qi.
Proceedings - 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018. ed. / Meikang Qiu. Institute of Electrical and Electronics Engineers Inc., 2018. p. 18-23 8421846 (Proceedings - 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

TY - GEN

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AU - Li, Zhen

AU - Liao, Qi

PY - 2018/7/27

Y1 - 2018/7/27

N2 - CAPTCHAs have become an ubiquitous defense used to protect open web resources from being exploited at scale. Traditionally, attackers have developed automatic programs known as CAPTCHA solvers to bypass the mechanism. With the presence of cheap labor in developing countries, hackers now have options to use human solvers. In this research, we develop a game theoretical framework to model the interactions between the defender and the attacker regarding the design and countermeasure of CAPTCHA system. With the result of equilibrium analysis, both parties can determine the optimal allocation of software-based or human-based CAPTCHA solvers. Counterintuitively, instead of the traditional wisdom of making CAPTCHA harder and harder, it may be of best interest of the defender to make CAPTCHA easier. We further suggest a welfare-improving CAPTCHA business model by involving decentralized cryptocurrency computation.

AB - CAPTCHAs have become an ubiquitous defense used to protect open web resources from being exploited at scale. Traditionally, attackers have developed automatic programs known as CAPTCHA solvers to bypass the mechanism. With the presence of cheap labor in developing countries, hackers now have options to use human solvers. In this research, we develop a game theoretical framework to model the interactions between the defender and the attacker regarding the design and countermeasure of CAPTCHA system. With the result of equilibrium analysis, both parties can determine the optimal allocation of software-based or human-based CAPTCHA solvers. Counterintuitively, instead of the traditional wisdom of making CAPTCHA harder and harder, it may be of best interest of the defender to make CAPTCHA easier. We further suggest a welfare-improving CAPTCHA business model by involving decentralized cryptocurrency computation.

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KW - Machine Solver

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DO - 10.1109/CSCloud/EdgeCom.2018.00013

M3 - Conference contribution

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A2 - Qiu, Meikang

PB - Institute of Electrical and Electronics Engineers Inc.

Y2 - 22 June 2018 through 24 June 2018

ER -

Li Z, Liao Q. CAPTCHA: Machine or human solvers? a game-theoretical analysis. In Qiu M, editor, Proceedings - 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018. Institute of Electrical and Electronics Engineers Inc. 2018. p. 18-23. 8421846. (Proceedings - 5th IEEE International Conference on Cyber Security and Cloud Computing and 4th IEEE International Conference on Edge Computing and Scalable Cloud, CSCloud/EdgeCom 2018). doi: 10.1109/CSCloud/EdgeCom.2018.00013

CAPTCHA: Machine or human solvers? a game-theoretical analysis

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