The purpose of this paper is to efficiently generate large nonsingular
matrix (S, S-1) pairs and permutation matrices over the binary field
using short keys. The motivation of this work is to provide a solution
to the long-key problem in algebraic-code cryptosystems. A special cl
ass of matrices which have exactly two 1's in each row and each column
is defined, and their properties are investigated to facilitate the c
onstruction of these algorithms. The time complexities of these algori
thms are studied and found to have O(n) n-bit word operations.