You say yes, I say no so we will have to disagree! Noodle this around. If raghead #1 wants to tell raghead #2 that tomorrow is the day he does not send out a 100 page document. He encrypts "tomorrow" using the selected book. Using only the bare minimum of code, out of a book with 200 pages, 40 lines per page, 80 characters per line. Any of the 5 characters can come from any page, any line with a source of 640,000 possible characters. To decrypt you need some pattern or some type of mathmatical repetition. Raghead 1 can use any "t", any "o", any "m", any R, and any "w" in an entire book.
Calling all number crunching type people what are the odds of finding the sequence of just 5 characters in 640,000 in the correct order?
The page,line,character sequence must be know. P,L,C or C,L,P or C,P,L etc then the book title must be known. You have to also know that this is the type of code being used.