TheCodeBreakers
portion of the name. Much of the Masonic ritual is printed in that form:
"Do u declr, upn ur honr, tt u r promptd to. . . ."
Another corollary is that more text is needed to solve a low-
redundancy cryptogram than one with a high-redundancy plaintext.
Shannon has managed to quantify the amount of material needed to
achieve a unique and unambiguous solution when the plaintext has a
known degree of redundancy. He calls the number of letters the "unicity
distance" (or "unicity point"), and he calculates it by means of a rather
complicated formula. This formula naturally differs for different ciphers,
but it always includes the redundancy as one of its terms. In his original
paper, in which he considered the redundancy of English at only 50 per
cent, Shannon found the unicity point for monoalphabetic substitution
at 27 letters, for polyalphabetics with known alphabets at twice the
period length, for those with unknown alphabets at 53 times the period
annaabi.ee 
