[Zha16] 
How to Avoid Obfuscation Using Witness PRFs
TCC 2016
[PDF]
[ePrint]
We propose a new cryptographic primitive called witness pseudorandom functions (witness PRFs). Witness PRFs are related to
witness encryption, but appear strictly stronger: we show that witness PRFs can be used for applications such as multiparty key
exchange without trsuted setup, polynomiallymany hardcore bits for any oneway function, and several others that were previously
only possible using obfuscation. Current candidate obfuscators are far from practical and typically rely on unnatural hardness
assumptions about multilinear maps. We give a construction of witness PRFs from multilinear maps that is simpler and much more
efficient than current obfuscation candidates, thus bringing several applications of obfuscation closer to practice. Our construction
relies on new but very natural hardness assumptions about the underlying maps that appear to be resistant to a recent line of attacks.
@inproceedings{Zha16, author = {Mark Zhandry}, title = {How to Avoid Obfuscation Using Witness PRFs}, booktitle = {Proceedings of TCC 2016}, misc = {Full version available at \url{http://eprint.iacr.org/2014/301}}, year = {2016} }

[GGHZ16] 
Functional Encryption without Obfuscation
TCC 2016
[PDF]
[ePrint]
Previously known functional encryption (FE) schemes for general circuits relied on indistinguishability obfuscation, which in
turn either relies on an exponential number of assumptions (basically, one per circuit), or a polynomial set of assumptions, but
with an exponential loss in the security reduction. Additionally these schemes are proved in an unrealistic selective security
model, where the adversary is forced to specify its target before seeing the public parameters. For these constructions, full
security can be obtained but at the cost of an exponential loss in the security reduction.
In this work, we overcome the above limitations and realize a fully secure functional encryption scheme without using indistinguishability
obfuscation. Specifically the security of our scheme relies only on the polynomial hardness of simple assumptions on multilinear maps.
@inproceedings{GGHZ16, author = {Sanjam Garg and Craig Gentry and Shai Halevi and Mark Zhandry}, title = {Functional Encryption without Obfuscation}, booktitle = {Proceedings of TCC 2016}, misc = {Full version available at \url{http://eprint.iacr.org/2014/666}}, year = {2016} }

[BLR^{+}15] 
Semantically Secure OrderRevealing Encryption: MultiInput Functional Encryption Without Obfuscation
EuroCrypt 2015
[PDF]
[ePrint]

[Zha14] 
Adaptively Secure Broadcast Encryption with Small System Parameters
[PDF]
[ePrint]
We build the first publickey broadcast encryption systems that simultaneously achieve adaptive security against arbitrary number
of colluders, have small system parameters, and have security proofs that do not rely on knowledge assumptions or complexity
leveraging. Our schemes are built from either composite order multilinear maps or obfuscation and enjoy a ciphertext overhead,
private key size, and public key size that are all polylogarithmic in the total number of users. Previous broadcast schemes with
similar parameters are either proven secure in a weaker static model, or rely on nonfalsifiable knowledge assumptions.
@misc{Zha14, author = {Mark Zhandry}, title = {Adaptively Secure Broadcast Encryption with Small System Parameters}, misc = {Full version available at \url{http://eprint.iacr.org/2014/757}}, year = {2014} }

[BWZ14] 
Low Overhead Broadcast Encryption from Multilinear Maps
CRYPTO 2014
[PDF]
[ePrint]
[slides]
We use multilinear maps to provide a solution to the longstanding problem of publickey broadcast encryption where all
parameters in the system are small. In our constructions, ciphertext overhead, private key size, and public key size are
all polylogarithmic in the total number of users. The systems are fully collusionresistant against any number of colluders.
All our systems are based on an O(log N)way multilinear map to support a broadcast system for N users. We present three
constructions based on different types of multilinear maps and providing different security guarantees. Our systems naturally
give identitybased broadcast systems with short parameters.
@inproceedings{BWZ14, author = {Dan Boneh and Brent Waters and Mark Zhandry}, title = {Low Overhead Broadcast Encryption from Multilinear Maps}, booktitle = {Proceedings of CRYPTO 2014}, misc = {Full version available at \url{http://eprint.iacr.org/2014/195}}, year = {2014} }

[GGHZ14] 
Adaptively Secure Attribute Based Encryption from Multilinear Maps
[PDF]
[ePrint]
We construct the first fully secure attribute based encryption (ABE) scheme that can handle access control policies
expressible as polynomialsize circuits. Previous ABE schemes for general circuits were proved secure only in an unrealistic
selective security model, where the adversary is forced to specify its target before seeing the public parameters, and full
security could be obtained only by complexity leveraging, where the reduction succeeds only if correctly guesses the adversary's
target string x^*, incurring a 2^{x^*} loss factor in the tightness of the reduction.
At a very high level, our basic ABE scheme is reminiscent of Yao's garbled circuits, with 4 gadgets per gate of the circuit, but
where the decrypter in our scheme puts together the appropriate subset of gate gadgets like puzzle pieces by using a cryptographic
multilinear map to multiply the pieces together. We use a novel twist of Waters' dual encryption methodology to prove the full
security of our scheme. Most importantly, we show how to preserve the delicate informationtheoretic argument at the heart of Waters'
dual system by enfolding it in an informationtheoretic argument similar to that used in Yao's garbled circuits.
@misc{GGHZ14, author = {Sanjam Garg and Craig Gentry and Shai Halevi and Mark Zhandry}, title = {Adaptively Secure Attribute Based Encryption from Multilinear Maps}, misc = {Full version available at \url{http://eprint.iacr.org/2014/622}}, year = {2014} }
