A protocol for computing a functionality is secure if an adversary in this protocol cannot cause moreharm than in an ideal computation where parties give their inputs to a trusted party which returns theoutput of the functionality to all parties. In particular, in the ideal model such computation is fair –all parties get the output. Cleve (STOC 1986) proved that, in general, fairnes...

We suggest protocols for secure computation of the sum, product, and some other functions of three or more elements of an arbitrary constructible ring, without using any one-way functions. A new input that we offer here is that, in contrast with other proposals, we conceal “intermediate results” of a computation, i.e., we do not let any party accumulate functions of other parties’ private numbe...

We present MCMix, an anonymous messaging system that completely hides communication metadata and can scale in the order of hundreds of thousands of users. Our approach is to isolate two suitable functionalities, called dialing and conversation, that when used in succession, realize anonymous messaging. With this as a starting point, we apply secure multiparty computation (“MC” or MPC) and proce...

Secure multiparty computations allow independent parties to collectively analyze data without compromising their input’s privacy. This data secrecy is guaranteed in some security model: in the passive model an adversary can only look at data visible to it, while in the active model adversaries can actively interfere in the computations. So from a security standpoint the active model is preferab...

With respect to a special class of access structures based on connectivity of graphs, we start from a linear secret sharing scheme and turn it into a secret sharing scheme with perfect security and exponentially small error probability by randomizing the reconstruction algorithm through random walks on graphs. It reduces the polynomial work space to logarithmic. Then we build the corresponding ...

There are many wonderful protocols in cryptography which are still waiting for their realization. Here we consider efficient solutions for secure electronic card games. Our contribution seems to be the first known practical implementation that requires no trusted third-party and simultaneously keeps the players’ strategies confidential. The provided open source library LibTMCG can be used for c...

In this paper we propose a novel protocol that allows suppliers and grid operators to collect users’ aggregate metering data in a secure and privacy-preserving manner. We use secure multiparty computation to ensure privacy protection. In addition, we propose three different data aggregation algorithms that offer different balances between privacy-protection and performance. Our protocol is desi...

We give improved upper bounds on the communication complexity of optimally-resilient secure multiparty computation in the cryptographic model. We consider evaluating an n-party randomized function and show that if f can be computed by a circuit of size c, then O(cnκ+nκ) is an upper bound for active security with optimal resilience t < n/2 and security parameter κ. This improves on the communica...