As Karen has pointed out, the W3C working groups has written a note about these systems. The note points out the following very generally: 1. It can be fairly easy to cir circumnavigate these systems using low cost labor or even possibly Machine learning algorithms. 2. Better results can often be had by limiting initial posting policies and by using auto spam detection services. 3. Having universal authenticators like facebook or google accounts can help, though I expect after recent privacy revelations people are backing down from linking diverse account with their Google or Facebook accounts. (Last sentence is mine and not a summary of one could obtain from the W3C document). 4. Using two factor systems can help. (We have discussed here some of the issues with SMS already) 5. Use logic or math challenges but have enough of them that a bot can't earn the entire set 6. In all cases, there should be a way for a person to contact an administrator of the system in question if they are unable to answer the challenges.
Karen also mentioned honey pot solutions. These basically are URL that look like a authentication page, but only but are not. If you see requests to the honey pot site you can briefly blacklist the originating IP address from being able to create an account as it is probably a web-crawler or other bot. The original article I read was here and if you are thinking of implementing such services a review of current literature would be recommended. https://www.w3.org/TR/turingtest/ <https://www.w3.org/TR/turingtest/> Jonathan Cohn -- The following information is important for all members of the Mac Visionaries list. If you have any questions or concerns about the running of this list, or if you feel that a member's post is inappropriate, please contact the owners or moderators directly rather than posting on the list itself. Your Mac Visionaries list moderator is Mark Taylor. You can reach mark at: [email protected] and your owner is Cara Quinn - you can reach Cara at [email protected] The archives for this list can be searched at: http://www.mail-archive.com/[email protected]/ --- You received this message because you are subscribed to the Google Groups "MacVisionaries" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/macvisionaries. For more options, visit https://groups.google.com/d/optout.
