Ronald L. Rivest

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problems<lb>To understand the class of polynomial-time solvable problems, we must first have a formal<lb>notion of what a "problem" is. We define an abstract problem Q to be a binary relation on a<lb>set I of problem instances and a set S of problem solutions. For example, an instance for<lb>SHORTEST-PATH is a triple consisting of a graph and two vertices.(More)
An encryption method is presented with the novel property that publicly revealing an encryption key does not thereby reveal the corresponding decryption key. This has two important consequences: (1) Couriers or other secure means are not needed to transmit keys, since a message can be enciphered using an encryption key publicly revealed by the intented(More)
This document describes the RC5 encryption algorithm, a fast symmetric block cipher suitable for hardware or software implementations. A novel feature of RC5 is the heavy use of data-dependent rotations. RC5 has a variable word size, a variable number of rounds, and a variable-length secret key. The encryption and decryption algorithms are exceptionally(More)
The MD4 message digest algorithm takes an input message of arbitrary length and produces an output 128-bit "fingerprint" or "message digest", in such a way that it is (hopefully) computationally infeasible to produce two messages having the same message digest, or to produce any message having a given prespecified target message digest. The MD4 algorithm is(More)
In this paper we formalize the notion of a ring signature, which makes it possible to specify a set of possible signers without revealing which member actually produced the signature. Unlike group signatures, ring signatures have no group managers, no setup procedures, no revocation procedures, and no coordination: any user can choose any set of possible(More)
This paper introduces a new representation for Boolean functions, called decision lists, and shows that they are efficiently learnable from examples. More precisely, this result is established for k-;DL – the set of decision lists with conjunctive clauses of size k at each decision. Since k-DL properly includes other well-known techniques for representing(More)
1 Introduction ~Ve present two simple micropayment schemes, "PayWord" and :'MicroMint," for making small purchases over the Internet. We were inspired to work on this problem by DEC's "Millicent" scheme[10]. Surveys of some electronic payment schemes can be found in Hallam-Baker [6], Schneier[16], and Wayner[18]. Our main goal is to minimize the number of(More)
Dwaine Clarke a, Jean-Emile Elien b, Carl Ellison c, Matt Fredette d, Alexander Morcos e and Ronald L. Rivest f,∗ a Room 226, MIT Lab for Computer Science, 200 Technology Square, Cambridge, MA 02139, USA E-mail: declarke@theory.lcs.mit.edu b Microsoft, One Microsoft Way, Redmond, WA 98052, USA E-mail: hbm@alum.mit.edu c Intel Corporation, 2111 NE 25th Ave,(More)