Date of Award


Document Type

Thesis (Ph.D.)


Department of Computer Science

First Advisor

Amit Chakrabarti


This thesis explores practical and theoretical aspects of several privacy-providing technologies, including tools for anonymous web-browsing, verifiable electronic voting schemes, and private information retrieval from databases. State-of-art privacy-providing schemes are frequently impractical for implementational reasons or for sheer information-theoretical reasons due to the amount of information that needs to be transmitted. We have been researching the question of whether relaxing the requirements on such schemes, in particular settling for imperfect but sufficient in real-world situations privacy, as opposed to perfect privacy, may be helpful in producing more practical or more efficient schemes. This thesis presents three results. The first result is the introduction of caching as a technique for providing anonymous web-browsing at the cost of sacrificing some functionality provided by anonymizing systems that do not use caching. The second result is a coercion-resistant electronic voting scheme with nearly perfect privacy and nearly perfect voter verifiability. The third result consists of some lower bounds and some simple upper bounds on the amount of communication in nearly private information retrieval schemes; our work is the first in-depth exploration of private information schemes with imperfect privacy.


Originally posted in the Dartmouth College Computer Science Technical Report Series, number TR2008-609.