We show how to construct length-preserving 1-1 one-way functions based on popular intractability assumptions (e.g., RSA, DLP). Such 1-1 functions should not be confused with (infinite) families of (finite) one-way permutations. What we want and obtain is a single (infinite) 1-1 one-way function. more >>>

We provide an exposition of three Lemmas which relate general properties of distributions with the exclusive-or of certain bit locations. The first XOR-Lemma, commonly attributed to U.V. Vazirani, relates the statistical distance of a distribution from uniform to the maximum bias of the xor of certain bit positions. The second ... more >>>

We suggest a candidate one-way function using combinatorial constructs such as expander graphs. These graphs are used to determine a sequence of small overlapping subsets of input bits, to which a hard-wired random predicate is applied. Thus, the function is extremely easy to evaluate: all that is needed is to ... more >>>

In this tutorial, selected topics of cryptology and of computational complexity theory are presented. We give a brief overview of the history and the foundations of classical cryptography, and then move on to modern public-key cryptography. Particular attention is paid to cryptographic protocols and the problem of constructing the key ... more >>>

We consider two of the most fundamental theorems in Cryptography. The first, due to Haastad et. al. [HILL99], is that pseudorandom generators can be constructed from any one-way function. The second due to Yao [Yao82] states that the existence of weak one-way functions (i.e. functions on which every efficient algorithm ... more >>>

We show that every language in NP has a *statistical* zero-knowledge argument system under the (minimal) complexity assumption that one-way functions exist. In such protocols, even a computationally unbounded verifier cannot learn anything other than the fact that the assertion being proven is true, whereas a polynomial-time prover cannot convince ... more >>>

Learning is a central task in computer science, and there are various formalisms for capturing the notion. One important model studied in computational learning theory is the PAC model of Valiant (CACM 1984). On the other hand, in cryptography the notion of ``learning nothing'' is often modelled by the simulation ... more >>>

We put forth a new computational notion of entropy, which measures the (in)feasibility of sampling high entropy strings that are consistent with a given protocol. Specifically, we say that the i'th round of a protocol (A, B) has _accessible entropy_ at most k, if no polynomial-time strategy A^* can generate ... more >>>