Editing Hill cipher (section)

{{short description|Substitution cipher based on linear algebra}}
{{more footnotes|date=February 2012}}
[[File:Hill's message protector.png|thumb|Hill's cipher machine, from figure 4 of the patent]]
In [[classical cryptography]], the '''Hill cipher''' is a [[polygraphic substitution|polygraphic substitution cipher]] based on [[linear algebra]]. Invented by [[Lester S. Hill]] in 1929, it was the first polygraphic cipher in which it was practical (though barely) to operate on more than three symbols at once.

The following discussion assumes an elementary knowledge of [[matrix (mathematics)|matrices]].