Constructing image captchas utilizing private information of the images

Abstract

An image CAPTCHA having one or more images, a challenge, and a correct answer to the challenge is constructed by selecting the one or more images from a plurality of candidate images based at least in part on each image's public information and private information. The private information of each of the images is accessible only to an entity responsible for constructing the CAPTCHA. Optionally, the one or more images are selected further based on the specific type of the CAPTCHA to be constructed.

1 . A method, comprising:
 accessing a plurality of candidate images, each candidate image comprising public information and private information;   selecting one or more images from the plurality of candidate images based at least in part on each image's public information and private information; and   constructing a CAPTCHA comprising the one or more images, a challenge, and a correct response,   wherein it is difficult for a computer to automatically determine the correct response using only the public information of each of the one or more images, and   wherein the private information of each of the one or more images is accessible only to an entity responsible for constructing the CAPTCHA.   
     
     
         2 . The method as recited in  claim 1 , wherein it is nearly impossible for the computer to automatically determine the correct response of the CAPTCHA using only the public information of each of the one or more images. 
     
     
         3 . The method as recited in  claim 1 , wherein it is impossible for the computer to automatically determine the correct response of the CAPTCHA using only the public information of each of the one or more images. 
     
     
         4 . The method as recited in  claim 1 , wherein selecting the one or more images from the plurality of candidate images is further based on a type of the CAPTCHA. 
     
     
         5 . The method as recited in  claim 4 , wherein:
 the one or more images comprises one image,   the challenge comprises describing a subject matter of the image, and   the image is selected from the plurality of candidate images based on the image lacking public information or having incorrect public information.   
     
     
         6 . The method as recited in  claim 4 , wherein:
 the one or more images comprises one target image and a plurality of choice images,   the challenge comprises selecting a response image from the plurality of choice images that has a subject matter that is most similar to a subject matter of the target image among the plurality of choice images, and   the target image and the plurality of choice images are selected from the plurality of candidate images based on the target image and the response image having different public information.   
     
     
         7 . The method as recited in  claim 6 , wherein the target image and the plurality of choice images are selected from the plurality of candidate images further based on the target image and each of the plurality of choice images other than the response image having similar public information. 
     
     
         8 . The method as recited in  claim 1 , further comprising obtaining the plurality of candidate images from the Internet. 
     
     
         9 . The method as recited in  claim 8 , further comprising obtaining the private information of each of the plurality of candidate images from search queries communicated to a search engine associated with the entity. 
     
     
         10 . The method as recited in  claim 8 , further comprising obtaining the private information of each of the plurality of candidate images from logs generated by a server associated with the entity, wherein the logs comprises data relating to Internet activities conducted via the server. 
     
     
         11 . A computer program product comprising a plurality of computer program instructions physically stored in a computer-readable medium, wherein the plurality of computer program instructions are operable to cause at least one computing device to:
 access a plurality of candidate images, each candidate image comprising public information and private information;   select one or more images from the plurality of candidate images based at least in part on each image's public information and private information; and   construct a CAPTCHA comprising the one or more images, a challenge, and a correct response,   wherein it is difficult for a computer to automatically determine the correct response using only the public information of each of the one or more images, and   wherein the private information of each of the one or more images is accessible only to an entity responsible for constructing the CAPTCHA.   
     
     
         12 . The computer program product as recited in  claim 11 , wherein it is nearly impossible for the computer to automatically determine the correct response of the CAPTCHA using only the public information of each of the one or more images. 
     
     
         13 . The computer program product as recited in  claim 11 , wherein it is impossible for the computer to automatically determine the correct response of the CAPTCHA using only the public information of each of the one or more images. 
     
     
         14 . The computer program product as recited in  claim 11 , wherein to select the one or more images from the plurality of candidate images is further based on a type of the CAPTCHA. 
     
     
         15 . The computer program product as recited in  claim 14 , wherein:
 the one or more images comprises one image,   the challenge comprises describing a subject matter of the image, and   the image is selected from the plurality of candidate images based on the image lacking public information or having incorrect public information.   
     
     
         16 . The computer program product as recited in  claim 14 , wherein:
 the one or more images comprises one target image and a plurality of choice images,   the challenge comprises selecting a response image from the plurality of choice images that has a subject matter that is most similar to a subject matter of the target image among the plurality of choice images, and   the target image and the plurality of choice images are selected from the plurality of candidate images based on the target image and the response image having different public information.   
     
     
         17 . The computer program product as recited in  claim 16 , wherein the target image and the plurality of choice images are selected from the plurality of candidate images further based on the target image and each of the plurality of choice images other than the response image having similar public information. 
     
     
         18 . The computer program product as recited in  claim 11 , wherein the plurality of computer program instructions are further operable to cause the at least one computing device to obtain the plurality of candidate images from the Internet. 
     
     
         19 . The computer program product as recited in  claim 18 , wherein the plurality of computer program instructions are further operable to cause the at least one computing device to obtain the private information of each of the plurality of candidate images from search queries communicated to a search engine associated with the entity. 
     
     
         20 . The computer program product as recited in  claim 18 , wherein the plurality of computer program instructions are further operable to cause the at least one computing device to obtain the private information of each of the plurality of candidate images from logs generated by a server associated with the entity, wherein the logs comprises data relating to Internet activities conducted via the server.