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An improved algorithm for computing logarithms overGF(p)and its cryptographic significance (Corresp.)

IEEE Transactions on Information TheoryPublished 1 January 1978
S.C. Pohlig, Martin E. Hellman
Citations1,186
SJR quartileQ1
SJR score1.46
SNIP1.76

TL;DR

An improved algorithm is derived which requires O =(\log^{2} p) complexity if p - 1 has only small prime factors and such values of p must be avoided in the cryptosystem.

Abstract

A cryptographic system is described which is secure if and only if computing logarithms over GF(p) is infeasible. Previously published algorithms for computing this function require O(p^{1/2}) complexity in both time and space. An improved algorithm is derived which requires O =(\log^{2} p) complexity if p - 1 has only small prime factors. Such values of p must be avoided in the cryptosystem. Constructive uses for the new algorithm are also described.

Keywords

Computer Science