Re: Use of simple schemes




Another scheme that is also (theoretically) very simple but faírly
expensive in computing is, I suppose, Hill's scheme employing matrices.
Now the Hill cipher is said to be weak in textbooks because, if the
matrix is n*n and one has n^2 units of corresponding plain and cipher
text, then the matrix can be found and the whole thing broken. But one
could afford to use a good sufficiently fast PRNG to dynamically
generate as many matrices as needed, using even any one n*n matrix for
much less than n^2 units of plaintext, when the computing cost is low
and the speed is acceptable. This way, Hill's scheme would be
practically applicable (eventually as a component of a larger scheme)
in my humble view.

M. K. Shen
.