@InProceedings{PerSon2002,
    author =       {Adrian Perrig and Dawn Song},
    title =        {New Directions for User Authentication: Reflex instead of Reflection},
    booktitle = {Workshop on Human Interactive Proofs},
    url = {/publications/papers/reflex-instead-of-reflection.pdf},
    year =     2002,
    address =      {Xerox PARC, Palo Alto, CA},
    month =    jan,
    day =          {9--11}
}