The Shannon cipher system with a guessing wiretapper

Date
1999-09
Authors
Merhav, N.
Arikan, E.
Advisor
Instructor
Source Title
IEEE Transactions on Information Theory
Print ISSN
0018-9448
Electronic ISSN
1557-9654
Publisher
Institute of Electrical and Electronics Engineers
Volume
45
Issue
6
Pages
1860 - 1866
Language
English
Type
Article
Journal Title
Journal ISSN
Volume Title
Abstract

The Shannon theory of cipher systems is combined with recent work on guessing values of random variables. The security of encryption systems is measured in terms of moments of the number of guesses needed for the wiretapper to uncover the plaintext given the cryptogram. While the encrypter aims at maximizing the guessing effort, the wiretapper strives to minimize it, e.g., by ordering guesses according to descending order of posterior probabilities of plaintexts given the cryptogram. For a memoryless plaintext source and a given key rate, a singleletter characterization is given for the highest achievable guessing exponent function, that is, the exponential rate of the th moment of the number of guesses as a function of the plaintext message length. Moreover, we demonstrate asymptotically optimal strategies for both encryption and guessing, which are universal in the sense of being independent of the statistics of the source. The guessing exponent is then investigated as a function of the key rate and related to the large-deviations guessing performance.

Course
Other identifiers
Book Title
Keywords
Cryptanalysis, Cryptography, Guessing, Shannon Cipher System
Citation
Published Version (Please cite this version)