We introduce a new technique, that we call punctured programs,
to apply indistinguishability obfuscation towards cryptographic
problems. We use this technique to carry out a systematic study of
the applicability of indistinguishability obfuscation to a variety of
cryptographic goals. Along the way, we resolve the 16-year-old open
question of Deniable Encryption, posed by Canetti, Dwork, Naor,
and Ostrovsky in 1997: In deniable encryption, a sender who is forced
to reveal to an adversary both her message and the randomness she used
for encrypting it should be able to convincingly provide ``fake''
randomness that can explain any alternative message that she would
like to pretend that she sent. We resolve this question by giving the
first construction of deniable encryption that does not require
any pre-planning by the party that must later issue a denial.
In addition, we show the generality of our punctured programs
technique by also constructing a variety of core cryptographic objects
from indistinguishability obfuscation and one-way functions (or close
variants). In particular we obtain: public key encryption, short
``hash-and-sign'' selectively secure signatures, chosen-ciphertext
secure public key encryption, non-interactive zero knowledge proofs
(NIZKs), injective trapdoor functions, and oblivious transfer. These
results suggest the possibility of indistinguishability
obfuscation becoming a ``central hub'' for cryptography.
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