CAPTCHAs, a form of Human Interactive Proof (HIP), are means of enforcing security on web systems... more CAPTCHAs, a form of Human Interactive Proof (HIP), are means of enforcing security on web systems. The resources of these web systems are misused by automated `bot' programs which indulge in spamming and other unscrupulous activities. The objective of a CAPTCHA is to successfully identify and allow access to human users as against to these bots. To defeat all currently known CAPTCHA breaking techniques, the STC scheme was proposed. In this paper, we expand the STC scheme by identifying its variants based on the nature of `Tagging'. These variations occur in Tagging of characters and/or numbers in the CAPTCHA image. An in-depth analysis based on Readability and Security of the variant schemes is performed and concluded with a comparative result.
CAPTCHAs are employed on web systems to differentiate between human users and automated programs ... more CAPTCHAs are employed on web systems to differentiate between human users and automated programs which indulge in spamming and other fraudulent activities. CAPTCHAs currently in use have been broken and rendered ineffective as a result of continuous evolution in CAPTCHA breaking. Thus, there is a need to employ stronger CAPTCHAs to keep these breaking attacks at bay while retaining ease of implementation on websites and ease of use for humans. In this paper, we introduce Sequenced Picture Captcha (SPC) which comprises of object pictures, each of which is accompanied by a Tag. The user is required to determine the logical sequence of the displayed object pictures based on the Tags. Hence, the user is required to identify both the object pictures and the Tags. Thus, Tagging introduces two levels of security. Moreover, being a Picture CAPTCHA, SPC inherits the advantages of high user convenience and simplicity of operation.
CAPTCHAs, a form of Human Interactive Proof (HIP), are means of enforcing security on web systems... more CAPTCHAs, a form of Human Interactive Proof (HIP), are means of enforcing security on web systems. The resources of these web systems are misused by automated `bot' programs which indulge in spamming and other unscrupulous activities. The objective of a CAPTCHA is to successfully identify and allow access to human users as against to these bots. To defeat all currently known CAPTCHA breaking techniques, the STC scheme was proposed. In this paper, we expand the STC scheme by identifying its variants based on the nature of `Tagging'. These variations occur in Tagging of characters and/or numbers in the CAPTCHA image. An in-depth analysis based on Readability and Security of the variant schemes is performed and concluded with a comparative result.
CAPTCHAs are employed on web systems to differentiate between human users and automated programs ... more CAPTCHAs are employed on web systems to differentiate between human users and automated programs which indulge in spamming and other fraudulent activities. CAPTCHAs currently in use have been broken and rendered ineffective as a result of continuous evolution in CAPTCHA breaking. Thus, there is a need to employ stronger CAPTCHAs to keep these breaking attacks at bay while retaining ease of implementation on websites and ease of use for humans. In this paper, we introduce Sequenced Picture Captcha (SPC) which comprises of object pictures, each of which is accompanied by a Tag. The user is required to determine the logical sequence of the displayed object pictures based on the Tags. Hence, the user is required to identify both the object pictures and the Tags. Thus, Tagging introduces two levels of security. Moreover, being a Picture CAPTCHA, SPC inherits the advantages of high user convenience and simplicity of operation.
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Papers by Aditya raj