By Topic

On the list and bounded distance decodibility of Reed-Solomon codes

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$33 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

2 Author(s)
Qi Cheng ; Sch. of Comput. Sci., Oklahoma Univ., USA ; Daqing Wan

For an error-correcting code and a distance bound, the list decoding problem is to compute all the codewords within a given distance to a received message. The bounded distance decoding problem is to find one codeword if there is at least one codeword within the given distance, or to output the empty set if there is not. Obviously the bounded distance decoding problem is not as hard as the list decoding problem. For a Reed-Solomon code [n, k]q, a simple counting argument shows that for any integer 0 < g < n, there exists at least one Hamming ball of radius n - g, which contains at least (ng)/qg-k many codewords. Let g(n, k, q) be the smallest positive integer g such that (ng)/qg-k < 1. One knows that k ≤ g(n, k, q) ≤ √nk ≤ n. For the distance bound up to n- √nk;, it is well known that both the list and bounded distance decoding can be solved efficiently. For the distance bound between n - √nk and n - g(n, k, q), we do not know whether the Reed-Solomon code is list, or bounded distance decodable, nor do we know whether there are polynomially many codewords in all balls of the radius. It is generally believed that the answers to both questions are no. There are public key cryptosystems proposed recently, whose security is based on the assumptions. In this paper, we prove: (1) List decoding can not be done for radius n - g(n, k: q) or larger, otherwise the discrete logarithm over Fqg(m, k, q)-k is easy. (2) Let h and g be positive integers satisfying q ≥ max(g2, (h-l)2+ε) and g ≥ (4/ε + 2)(h + 1) for a constant ε > 0. We show that the discrete logarithm problem over Fqh can be efficiently reduced by a randomized algorithm to the bounded distance decoding problem of the Reed-Solomon code [q, g - h]q with radius q - g. These results show that the decoding problems for the Reed-Solomon code are at least as hard as the discrete logarithm problem over finite fields. The main tools to obtain these results are an interesting connection between the problem of list-decoding of Reed-Solomon code and the problem of discrete logarithm over finite fields, and a generalization of Katz's theorem on - representations of elements in an extension finite field by products of distinct linear factors.

Published in:

Foundations of Computer Science, 2004. Proceedings. 45th Annual IEEE Symposium on

Date of Conference:

17-19 Oct. 2004