The Bletchley Park 1944 Cryptographic Dictionary formatted by Tony ...

The Bletchley Park 1944 Cryptographic Dictionary formatted by Tony Sale (c) 2001
- 41 -
GOOD :
1. (of code-groups). Occurring or likely to occur a sufficient
number of times to be of assistance to the cryptographer.
2. (of difference). Arising from good code-groups.
GOOD DIFFERENCE :
A difference which is equal to, and may be, the difference between
two good groups.
GOOD GROUP :
1. A code-group of which the total occurrences amount to more than a
given proportion of the material under consideration; a common
group.
2. (in a code of which the groups have known limitations). A code
group which has the proper limitation and is so known to be not
corrupt.
GRAMMATICAL GROUP :
A code group indicating which of the alternative meanings or endings
assigned to a particular code group is to be taken.
GREEN :
(of trigrams). Taken from the Heeressignaltafel.
GRID :
(in transposition). Used for cage.
GRILLE
(in Transposition).
1. A cage in which certain squares are blacked-out or otherwise marked
as not to be used.
2. A perforated card or disc for determining which squares of a cage
are to be used or have been used.
GRONSFELD CIPHER :
A letter-substitution cipher system using a numerical key, and therefore
characterized by a limitation on the number of ways in which a particular
letter can be enciphered, sc. a letter is enciphered either by itself
or one of nine other letters.