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recommendations for the next generation of mobile
captchas.
ACKNOWLEDGEMENTS
Sonia Chiasson holds a Canada Research Chair in Hu-
man Oriented Computer Security acknowledges the
Natural Sciences and Engineering Research Council
of Canada (NSERC) for funding the Chair and a Dis-
covery Grant. The authors also acknowledge funding
from NSERC ISSNet and thank P.C. van Oorschot for
his valuable feedback on this project.
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