🚀 go-pugleaf

	I have been one of those who has been unenthusiastic about book
	codes in the past, but I have just read "Handbook for Spies" by
	Alexander Foote and in one of the appendices he described the
	cipher system he used whilst working for the Soviets in Switzerland
	in WWII in the legendary Lucy ring.  Briefly:

1.      Rearrange alphabet by the Playfair keyword method.
	The alphabet includes the figures @ and .

2.      Assign numerical values to letters as follows:

	E       1
	T       2
	A       3
	S       5
	O       6
	R       7
	I       8
	N       9  (not 01, 02 etc.)

3.      In the order of the rearranged alphabet, assign the values 01-09,
	and 40-49 and encrypt the message, rearrange into five figure groups.

4.      Take a passage from a book of the same length as the message and
	encrypt using the same substitution.  Rearrange into five-figure
	groups and add to the corresponding groups of the original message.

5.      Two groups including a check group and page-line-first word
	identifier are buried at specific groups in the body of the message.


	Decryption is then a matter of arithmetic.  If it was good enough
	for the Soviets, it must be stronger than I thought.  Apologies
	to anybody I may have flamed.

	Alec Chambers.