Showing papers on "Alice and Bob published in 1996"

Hiding Data in the OSI Network Model

Abstract: Rather than searching for the holy grail of steganography, this paper presents the basis for development of a tool kit for creating and exploiting hidden channels within the standard design of network communications protocols. The Alice and Bob analogy, derived from cryptology, is used to present network protocols in a way that more clearly defines the problem. Descriptions of typical hidden channel design for each layer of the Open Systems Interconnect (OSI) network model are given. Methods of hiding and detection probabilities are summarized. Denying Bob and Alice the ability to communicate electronically may be the only absolute solution.

Towards Characterizing When Information-Theoretic Secret Key Agreement Is Possible

Abstract: This paper is concerned with information-theoretically secure secret key agreement in the general scenario where three parties, Alice, Bob, and Eve, know random variables X, Y, and Z, respectively, with joint distribution P xyz , for instance resulting from receiving a sequence of random bits broadcast by a satellite. We consider the problem of determining for a given distribution P xyz whether Alice and Bob can in principle, by communicating over an insecure channel accessible to Eve, generate a secret key about which Eve's information is arbitrarily small. When X, Y, and Z are random variables that result from a binary random variable being sent through three arbitrary independent channels, it is shown that secret key agreement is possible if and only if I(X;Y¦Z) >0, i.e., under the sole condition that X and Y have some (arbitrarily weak) statistical dependence when given Z.

Short Distance Applications of Quantum Cryptography

Abstract: We present an identification protocol based on quantum mechanics. The first user, Alice, needs to identify herself in front of a second user, Bob, by means of a password, known only to both. The safety requirement for Alice is that somebody impersonating Bob, who only pretended to know Alice’s password, shall not be able to obtain information on the password from the exchange. This is an example of a potentially practical new application of quantum mechanics to cryptography.