CryptoDay at Cornell-Tech

Nov 7, 2014 (Friday) at Cornell-Tech, 111 8th Avenue #302 (Room “Touchdown”)


9:30 – 10:00. Introduction/Coffee
10:00 – 10:50.
Mohammad Mahmoody, University of Virginia
On the Impossibility of Cryptography with Tamperable Randomness
11:00 – 11:50. Dana Dachman-Soled, UMD
Adaptively Secure, Universally Composable, Multi-Party Computation in Constant Rounds
12:00 – 2:00. Lunch (not provided)
2:00 – 2:50. Ben Fisch, 1010data
Physical Zero Knowledge Proofs of Physical Properties
3:00 – 3:50. abhi shelat,  University of Virginia
The Gate, The Cut, The Check and their Question


Registration for attending this event is free but mandatory. You can register by going to the registration formPlease register by Wed. Nov 5, 2014 11:59 PM. Only registered participants will be allowed on Cornell NYC Tech premises


Cornell Tech
111 8th Avenue #302
New York, NY 10011
Room “Touchdown”.

Please check-in at the lobby first where you will get a sticker. Then go to the third floor and follow the corridor for Cornell Tech, and then someone will greet you in the lobby and tell you how to get to “Touchdown.”


Tal Rabin (IBM)
with the help and support of Rafael Pass (Cornell).


  • On the Impossibility of Cryptography with Tamperable Randomness / Mohammad Mahmoody (University of Virginia)We study of the security of cryptographic primitives in the presence of efficient tampering attacks to the randomness of honest parties. More precisely, we consider p-tampering attackers that may tamper with each bit of the honest parties’ random tape with probability p, and have to do so in an “online” fashion. We present both positive and negative results:Negative: Any secure encryption scheme, bit commitment scheme, or zero- knowledge protocol can be “broken” with advantage p by a p-tamperingattack. The core of this result is a novel technique for biasing the output of bounded-value functions, which may be of independent interest.
    Positive: Assuming the existence of one-way functions, cryptographic primitives such as signatures, identification protocols can be made resilient to p-tamperingattacks for any p = 1/n^c, where c > 0 is a constant and n is the security parameter.Joint work with Per Austrin, Kai-Min Chung, Rafael Pass, and Karn Seth
  • Adaptively Secure, Universally Composable, Multi-Party Computation in Constant Rounds / Dana Dachman Soled (UMD)  
    Cryptographic protocols with adaptive security ensure that security holds against an adversary who can dynamically determine which parties to corrupt as the protocol progresses—or even after the protocol is finished. In the setting where all parties may potentially be corrupted, and secure erasure is not assumed, it has been a long-standing open question to design secure-computation protocols with adaptive security running in constant rounds.
    Here, we show a constant-round, universally composable protocol for computing any functionality, tolerating a malicious, adaptive adversary corrupting any number of parties. Interestingly, our protocol can compute all functionalities, not just adaptively well-formed ones.
    Joint work with Jonathan Katz and Vanishree Rao
  • Physical Zero Knowledge Proofs of Physical Properties / Ben Fisch (1010data)
    Is it possible to prove that two DNA-fingerprints match, or that they do not match, without revealing any further information about the fingerprints? Is it possible to prove that two objects have the same design without revealing the design itself? In the digital domain, zero-knowledge is an established concept where a prover convinces a verifier of a statement without revealing any information beyond the statement’s validity. However, zero-knowledge is not as well-developed in the context of problems that are inherently physical. In this talk, we will discuss protocols that prove physical properties of physical objects without revealing further information. We suggest a paradigm for formally defining, modeling, and analyzing physical zero-knowledge (PhysicalZK) protocols in the Universal Composability framework, and demonstrate applications to DNA profiling and neutron radiography. We also explore the benefits of public observation proofs, a physical analog of public-coin proofs. (Joint work with Moni Naor and Daniel Freund).
  • The Gate, The Cut, The Check and their Question / abhi shelat (University of Viriginia)

    I will discuss three exciting recent improvements to the garbled circuits approach to secure computation that bring to light the remaining uncertainty about this rather well-studied cryptographic technique.


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