Cryptanalysis of General Polygraphic Substitutions
Polygraphic systems do provide a significant improvement in security over monoalphabetic substitutions. Given an individual letter 'E' in a message, it could be encrypted using any of 52 instructions depending on its location and neighbors, which can be used to great advantage to mask the frequency of individual letters. However, the security boost is limited; while it generally requires a larger sample of text to crack, it can still be done by hand.
Read more about this topic: Polygraphic Substitution
Famous quotes containing the word general:
“There is a mortifying experience in particular, which does not fail to wreak itself also in the general history; I mean “the foolish face of praise,” the forced smile which we put on in company where we do not feel at ease, in answer to conversation which does not interest us. The muscles, not spontaneously moved but moved, by a low usurping wilfulness, grow tight about the outline of the face, with the most disagreeable sensation.”
—Ralph Waldo Emerson (1803–1882)