TheCodeBreakers
an extensive furnishing of information, as bn for battalion, that they may
not only make plaintexts harder to solve, but may themselves function as
a rough form of cryptography. Two gossips, for example, may refer to a
third party by her initials. They hope that no one within hearing will have
sufficient knowledge of the contextual situation to restore the eliminated
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
annaabi.ee 
