STOC

Every function of n inputs can be efficiently computed by a complete network of n processors in such a way that:

• If no faults occur, no set of size t < n/2 of players gets any additional information (other than the function value),

• Even if Byzantine ...

Under the assumption that each pair of participants can communicate secretly, we show that any reasonable multiparty protocol can be achieved if at least 2n/3 of the participants are honest. The secrecy achieved is unconditional. It does not rely on any ...

Suppose your netmail is being erratically censored by Captain Yossarian. Whenever you send a message, he censors each bit of the message with probability 1/2, replacing each censored bit by some reserved character. Well versed in such concepts as ...

We present a digital signature scheme which combines high security with the property of being based on a very general assumption: the existence of trapdoor permutations. Previous signature schemes with comparable levels of security were based on ...

Two conflicting goals play a crucial role in the design of routing schemes for communication networks. A routing scheme should use as short as possible paths for routing messages in the network, while keeping the routing information stored in the ...

We investigate the complexity of reasoning about knowledge and time, with emphasis on the case of asynchronous time. We show that in the case of no forgetting (Ladner and Reif's Tree Logic of Protocols, TLP) the validity problem is complete for ...

Most of the research in concurrency control has been based on the existence of strong synchronization primitives such as test and set. Following Lamport, recent research promoting the use of weaker primitives, “safe” rather than “atomic,” has resulted ...

Three parameters characterize the performance of a probabilistic algorithm: T, the runtime of the algorithm; Q, the probability that the algorithm fails to complete the computation in the first T steps and R, the amount of randomness used by the ...

We show that interaction in any zero-knowledge proof can be replaced by sharing a common, short, random string. We use this result to construct the first public-key cryptosystem secure against chosen ciphertext attack.

Quite complex cryptographic machinery has been developed based on the assumption that one-way functions exist, yet we know of only a few possible such candidates. It is important at this time to find alternative foundations to the design of secure ...

While the intuition underlying a zero knowledge proof system [GMR85] is that no “knowledge” is leaked by the prover to the verifier, researchers are just beginning to analyze such proof systems in terms of formal notions of knowledge. In this paper, we ...

We exhibit randomized Byzantine agreement (BA) algorithms achieving optimal running time and fault tolerance against all types of adversaries ever considered in the literature. Our BA algorithms do not require trusted parties, preprocessing, or non-...

We compare the communication complexity of discrete functions under different modes of computation, unifying and extending several known models. Protocols can be deterministic, nondeterministic or probabilistic and in the last case the error probability ...

We prove θ(n log n) bounds for the deterministic 2-way communication complexity of the graph properties CONNECTIVITY, s-t-CONNECTIVITY and BIPARTITENESS (for arbitrary partitions of the variables into two sets of equal size). The proofs are based on ...

We study energy consumption in CMOS-style VLSI circuits, where a wire of length / consumes energy Θ(l)when switching. Three model are considered: the uniswitch model where a wire is assumed to switch at most once if the input changes, the multiswitch ...

NP-complete problems should be hard on some (may be extremely rare) instances. But on generic instances many such problems (especially related to random graphs) have been proven easy. We show the intractability of random instances of a graph coloring ...

We define a natural variant of NP, MAX NP, and also a subclass called MAX SNP. These are classes of optimization problems, and in fact contain several natural, well-studied ones. We show that problems in these classes can be approximated with some ...

The permanent of an n x n matrix A with 0-1 entries a_ij is defined by per (A) = Σ/σ Π/n-1/i=ο a_iσ(i), where the sum is over all permutations σ of [n] = {0, …, n - 1}. Evaluating per (A) is equivalent to counting perfect matchings (1-factors) in the ...

We show that, over an arbitrary ring, the functions computed by polynomial-size algebraic formulas are also computed by polynomial-length algebraic straight-line programs which use only 3 registers (or 4 registers, depending on some definitions). We ...

We construct a family (G_p | p) of directed acyclic graphs such that any black pebble strategy for G_p requires p² pebbles whereas 3p+1 pebbles are sufficient when white pebbles are allowed.

Log-size Parabolic Clique Problem is a version of Clique Problem solvable in linear time by a log-space nondeterministic Turning machine. However, no deterministic machine (in a very general sense of this term) with sequential-access read-only input ...

We present a universal randomized method called Local Best-First Search for parallelizing sequential branch-and-bound algorithms. The method executes on a message-passing multiprocessor system, and requires no global data structures or complex ...

An efficient deterministic polynomial time algorithm is developed for the sparse polynomial interpolation problem. The number of evaluations needed by this algorithm is very small. The algorithm also has a simple NC implementation.

Randomized algorithms are analyzed as if unlimited amounts of perfect randomness were available, while pseudorandom number generation is usually studied from the perspective of cryptographic security. Bach recently proposed studying the interaction ...