An Image-Based CAPTCHA Scheme Exploiting Human Appearance Characteristics

• Sajida Kalsoom,
• Sheikh Ziauddin,
• Abdul Rehman Abbasi,

Vol. 6, No. 2, February 27, 2012
10.3837/tiis.2012.02.017, Download Paper (Free):

• Human Interactive Proof
• CAPTCHA
• Usability
• Security
• human appearance characteristics

Abstract

CAPTCHAs are automated tests that are there to avoid misuse of computing and information resources by bots. Typical text-based CAPTCHAs are proven to be vulnerable against malicious automated programs. In this paper, we present an image-based CAPTCHA scheme using easily identifiable human appearance characteristics that overcomes the weaknesses of current text-based schemes. We propose and evaluate two applications for our scheme involving 25 participants. Both applications use same characteristics but different classes against those characteristics. Application 1 is optimized for security while application 2 is optimized for usability. Experimental evaluation shows promising results having 83% human success rate with Application 2 as compared to 62% with Application 1.

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