The 1944 Bletchley Park Cryptographic Dictionary

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DOG CODE :

A code in which code-names or other letter-groups are substituted for units of the vocabulary before encodement; a code within a code.

DOMINANT :

Applied to a letter in a code or cipher group which receives special treatment or has a special function in the reciphering.

DORMANT :

(of a code or cipher system or any part thereof). Temporarily out of use; suspended.

DOTTERY, DOTTING :

Hand method of determining stecker of Enigma key when Wheel-order, Ring- stellung and message setting have been probably inferred. One stecker- pairing is assumed and the letters involved are deciphered throughout the message, producing (if the assumption is correct) a series of deciphered letters which are the steckers of the clear-text letters in these positions. A frequency count of these letters is made (by putting a dot for each occurrence opposite the letter on counting sheet). From this further steckers are inferred, and the process is continued.

DOUBLE CHI :

Double transposition.

DOUBLE-INPUT WARSPITE :

Type of Bombe in which current is put in at two points, designed to deal with a menu which consists of two dis-connected chains and to stop only when current gets round both simultaneously.

DOUBLE-LINER :

(in double Playfair with two squares). An encipherment of a bigram involving only one line in each of the two operations.

DOUBLE PLAYFAIR :

1. Playfair in which two distinct operations are involved in each bigram substitution.

2. Playfair using two letter-squares and two distinct operations in enciphering each bigram;

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