Paper 2010/543

Functional Encryption: Definitions and Challenges

Dan Boneh, Amit Sahai, and Brent Waters


We initiate the formal study of functional encryption by giving precise definitions of the concept and its security. Roughly speaking, functional encryption supports restricted secret keys that enable a key holder to learn a specific function of encrypted data, but learn nothing else about the data. For example, given an encrypted program the secret key may enable the key holder to learn the output of the program on a specific input without learning anything else about the program. We show that defining security for functional encryption is non-trivial. First, we show that a natural game-based definition is inadequate for some functionalities. We then present a natural simulation-based definition and show that it (provably) cannot be satisfied in the standard model, but can be satisfied in the random oracle model. We show how to map many existing concepts to our formalization of functional encryption and conclude with several interesting open problems in this young area.

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Published elsewhere. Unknown where it was published
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bwaters @ cs utexas edu
2011-01-04: last of 3 revisions
2010-10-25: received
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      author = {Dan Boneh and Amit Sahai and Brent Waters},
      title = {Functional Encryption: Definitions and Challenges},
      howpublished = {Cryptology ePrint Archive, Paper 2010/543},
      year = {2010},
      note = {\url{}},
      url = {}
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