Enhancing the security of image CAPTCHAs through noise addition

David Lorenzi, Emre Uzun, Jaideep Vaidya, Shamik Sural, Vijayalakshmi Atluri

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations


Text based CAPTCHAs are the de facto method of choice to ensure that humans (rather than automated bots) are interacting with websites. Unfortunately, users often find it inconvenient to read characters and type them in. Image CAPTCHAs provide an alternative that is often preferred to text-based implementations. However, Image CAPTCHAs have their own set of security and usability problems. A key issue is their susceptibility to Reverse Image Search (RIS) and Computer Vision (CV) attacks. In this paper, we present a generalized methodology to transform existing images by applying various noise generation algorithms into variants that are resilient to such attacks. To evaluate the usability/security tradeoff, we conduct a user study to determine if the method can provide “usable” images that meet our security requirements – thus improving the overall security provided by Image CAPTCHAs.

Original languageEnglish (US)
Title of host publicationICT Systems Security and Privacy Protection - 30th IFIP TC 11 International Conference, SEC 2015, Proceedings
EditorsDieter Gollmann, Hannes Federrath
PublisherSpringer New York LLC
Number of pages15
ISBN (Print)9783319184661
StatePublished - 2015
Event30th IFIP TC 11 International Information Security and Privacy Conference, SEC 2015 - Hamburg, Germany
Duration: May 26 2015May 28 2015

Publication series

NameIFIP Advances in Information and Communication Technology
ISSN (Print)1868-4238


Other30th IFIP TC 11 International Information Security and Privacy Conference, SEC 2015

All Science Journal Classification (ASJC) codes

  • Information Systems
  • Computer Networks and Communications
  • Information Systems and Management

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